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Transcript of Photo: The Daily Galaxy. CPBM Objectives (chapter 8) 1) Identify fire behavior terms 2) Explain the...
Photo The Daily Galaxy
CPBM Objectives (chapter 8)
1) Identify fire behavior terms2) Explain the fire triangle3) Discuss the major elements of the fire
environment4) List and explain the three methods of
heat transfer5) List fuel characteristics which govern
combustion
CPBM Objectives (chapter 8)
6) Identify Fuel Models and examples in Florida
7) Explain the difference between fire intensity and severity and how both can be regulated and measured
8) Define residence time and why it is significant in Rx fire
9) Discuss indicators of erratic or potentially erratic fire behavior
Wind
REAR
LEFT
FLANK
RIGHT FLA
NK
FINGER
HEAD
SPOT FIRE
UNBURNED ISLAND
Surface Fire Burning in surface fuels Grass shrubs litter
Ground Fire Smoldering in ground fuels duff peat roots stumps
Crown Fire Burning in aerial fuels Crowns or canopy of the overstory May or may not be independent of surface fire
Photo Univ of Toronto Fier Lab
Photo News Provider
Spotting ndash burning or glowing embers being transported in the air
Torching ndash Movement of fire from the surface to the crowns of individual trees
Flare Up ndash A sudden increase in ROS and Intensity
Fuel Oxygen
Heat
The Fire TriangleThe Fire Triangle
Energy release in the form of heat and light when oxygen combines Energy release in the form of heat and light when oxygen combines with a combustible material (fuel) at a suitably high temperaturewith a combustible material (fuel) at a suitably high temperature
Photosynthesis converts radiant energy to stored chemical energy (CO2 + H2O ---light-----gt C6H12O6 + O2)
Combustion reverses photosynthesis(C6H12O6 + O2 ---high temperature-----gt H2O + CO2 + heat and light)
(fuel) (325 C for wood)
Same process as decay and decomposition Begins with endothermic reaction becomes exothermic Produces thermal radiant and kinetic energy
Extinction insufficient heat to sustain combustion
HEAT
WATER ampORGANICGASES
Pre-Ignition
VISIBLE SMOKE
Smoldering
CO CO2
Glowing
2CO WATER
VISIBLE SMOKE
Flaming
4 Phases of Combustion
Pre-ignition Requires heatenergy input to
increase surface temperature gt200˚C
Dehydration Volatilization of waxes oils other
extractives Pyrolysis (chemical decomposition of
organic matter without Oxygenndash inside fuels emits volatiles)
Volatiles either condense into particles (smoke) or are consumed during flaming combustion
HEAT
WATER ampORGANICGASES
Pre-Ignition
Ignition Transition to flaming
combustion gases released by pyrolysis ignite
Surface temperatures around 320 C (600F)
Heat released by combustion brings other fuels to ignition
Flaming combustion Surface temperatures 200- 500˚
C Combustible volatiles ignite
above surface creating flame the GASES are burning not the fuel itself
Combustion occurs in zone above fuel surface
Oxidation produces heat CO2 H2O and incompletely degraded organic compounds
Smoke includes these + other gases which condense or reform above flame zone
2CO WATER
VISIBLE SMOKE
Flaming
Smoldering No visible flames Surface temperatures lt 500 C Carbon buildup on surface reduces gas
production that would maintain flame Occurs when fuels tightly packed Surface char oxidizes to CO2 H2O ash Continued oxidation of other
compounds Smoldering duff and ground fires raise
soil temperature and can kill roots Large quantities of smoke
VISIBLE SMOKE
Smoldering
A result of incomplete combustion Major constituents
Particulate matter Solid or liquid particle suspended in
atmosphere Condensed hydrocarbons and tar
materials Entrained fragments of vegetation and
ash CO2 and CO H2O Gaseous hydrocarbons
Smokevolume burned increases for Low intensity fires in moist or living
fuels High rates of spread (amp less efficient
combustion)
CO CO2
GlowingbullAll volatiles have already been driven off oxygen reaches the combustion surfaces and there is no visible smoke (products are CO2 and CO)bullOxidation of solid fuel accompanied by incandescencebullThis phase follows smoldering combustion continues until temperature drops or only non-combustible ash remains
Radiation For example the sun and your handhellip Electromagnetic waves transfer heat to
fuel surface only
Accounts for most drying and heating of fuel surfaces ahead of flame or on opposite steep slopesndash radiates in all directions
Radiation For example the sun and your handhellipFor example the sun and your handhellip Electromagnetic waves transfer heat to fuel Electromagnetic waves transfer heat to fuel
surface onlysurface only
Accounts for most drying and heating of Accounts for most drying and heating of fuel surfaces ahead of flame or on opposite fuel surfaces ahead of flame or on opposite steep slopesndash radiates in all directionssteep slopesndash radiates in all directions
Convection Vertical (or other direction)
movement of gas or liquid as heat rises
Heats plant foliage above surface fires and fuels ahead of the flame on steep slopes or if wind driven
Carries firebrands away from fire spotting potential
Can create enormous columns and drive fire behavior
ConvectionConvection Vertical (or other direction) movement of Vertical (or other direction) movement of
gas or liquid as heat risesgas or liquid as heat rises Heats plant foliage above surface fires Heats plant foliage above surface fires
and fuels ahead of the flame on steep and fuels ahead of the flame on steep slopes or if wind drivenslopes or if wind driven
Carries firebrands away from fire Carries firebrands away from fire spotting potentialspotting potential
Can create enormous columns and drive Can create enormous columns and drive fire behaviorfire behavior
Heat Transfer ProcessesHeat Transfer Processes
ConductionConduction Transfer by molecular activity Transfer by molecular activity
withinwithin a solid object a solid object Primary method for raising Primary method for raising
temperatures within large fuelstemperatures within large fuels Occurs between objectsfuels Occurs between objectsfuels
that are in contactthat are in contact Transfers heat in dense fuels Transfers heat in dense fuels
requiring additional heat to reach requiring additional heat to reach ignitionignition
Rate of spread (ROS) rate at which fire front advances through forest fuel (ftsec chainsmin)
Residency Time Duration for flaming combustion to pass a specific location
Flame Length amp Depth
Residency Time = Flame DepthROS
Intensity ndash rate of heat energy during combustion Reaction intensity per unit area (BTUft-2min-1) Fireline Intensity per unit length of the fire front (BTUft-1min-
1)
I = hwr
I fireline intensityh fuel heat contentw weight of fuel consumed per unit arear rate of spread
Flame Length is a good estimate of intensity
Severity Impact of fire on the environment Plants animals soils water
SE
VE
RIT
Y
INTENSITY
LOW
HIGH
HIGHLOW
Backing fire in long unburned longleaf pine
Stand replacing fire in mixed conifer forests
Head fire in frequently burned longleaf pine
Chaparral Brush Fires
1 Weather
2 Fuels 3 Topography
Surface Fuels Grasses Shrubs Litter (leaves)
Woody debris
Ground Fuels Duff (partially
decomposed)
Peat Roots Stumps
mineral soil
litter
fermentation layerhumus
Duff
Aerial Fuels Crown or canopy of
overstory
Ladder Fuels (located between crown and surface fuels)
Smaller trees Vines
Size and Shape Surface areavolume
ratio Grasses Palmetto Branches Logs
10001
401
Particle Density
Fuel Chemistry Volatile oils
Mineral Content Dampening effect on
combustion
Heat Content (stored energy)
6000-12000 BTUlb
Fuel Arrangement Vertical Grasses amp shrubs
Horizontal Litter Downed woody debris
Fuel Loading By size classes
Compactness Bulk density (fuel loadfuelbed volume)
Packing ratio (fuelbed densityparticle density)
Continuity Vertical Horizontal
ALL FUELBED PROPERTIES
Fuel Moisture Content (FMC) Large dampening effect on
combustion Heat sink
FMC changes hourly daily and seasonally
Fuel Moisture Content () = (Water Weight Dry Fuel Weight) x 100
What influences FMC In Dead Fuels Precipitation (amount
and duration) Temperature Relative humidity Wind
Equilibrium Moisture Content For a given temperature and RH dead fuel
will reach a FMC at equilibrium Environmental conditions are not constant Fuel is constantly changes FMC to reach
EMC
The lag time to reach EMC depends on particle size
Timelag categories for dead woody fuels
Timelag Class Fuel Diameter
Timelag Range (hr)
1 Hour 0-14rdquo 0-2
10 Hour frac14rdquo-1rdquo 2-20
100 Hour 1-3rdquo 20-200
1000 Hour 3-8rdquo 200-2000
Timelag or ldquoresponse timerdquo is the time it takes for 63 of the change to occur between one EMC and a second EMC when a fuel in equilibrium with a stable environmental condition is suddenly exposed to a different stable environmental condition
Small diameter fuels react quickly to hourly and daily changes Important to monitor
Large diameter fuels react more to seasonal changes California versus Florida
Fine fuels drive fire behavior
Moisture of Extinction Dead 12-40 Live gt120
Available Fuel
Florida Fine Fuel Moisture Calculation Chart
httpwwwfl-dofcomwildfirerx_traininghtmlcbc
Live Fuels FMC can be much higher than dead
fuels (100-300) Influenced by Drought (KBDI) RH Wind
Ignition of live fuels may largely depend the combustion characteristics of other fuels (eg dead surface fuels)
Duff Moisture Very dry to very moist lt30 FMC duff can burn on its own Potential for tree mortality in
burning long unburned forests May smolder for long durations May cause lots of smoke
FMCWind
Increases O2 Bends flames Increases ROS Dries fuels
convectionwind
radiation
conduction
Slopes Similar effect as
wind Bends flames ROS higher
upslope
Slope Positiontop middle bottom
Aspect
Other topographic features Valleys Box Canyons Steep draws Elevation
ELEVATION
Indicators (on a Rx burn) KBDIgt500 FMC (fine) lt7 RHlt30 Cold front approaching Gusty winds Dust devilsfire whirls Just inland from seabreeze Well-defined convection column Thunderstorms Spotting DI approaching 70
Fire Behavior Prediction Models (eg BehavePlus)
INPUTS OUTPUTSFuel characteristics Rate of
SpreadFMC Fireline IntensitySlope Flame LengthsWind and morehellip
- Slide 9
- Slide 15
- Slide 46
-
CPBM Objectives (chapter 8)
1) Identify fire behavior terms2) Explain the fire triangle3) Discuss the major elements of the fire
environment4) List and explain the three methods of
heat transfer5) List fuel characteristics which govern
combustion
CPBM Objectives (chapter 8)
6) Identify Fuel Models and examples in Florida
7) Explain the difference between fire intensity and severity and how both can be regulated and measured
8) Define residence time and why it is significant in Rx fire
9) Discuss indicators of erratic or potentially erratic fire behavior
Wind
REAR
LEFT
FLANK
RIGHT FLA
NK
FINGER
HEAD
SPOT FIRE
UNBURNED ISLAND
Surface Fire Burning in surface fuels Grass shrubs litter
Ground Fire Smoldering in ground fuels duff peat roots stumps
Crown Fire Burning in aerial fuels Crowns or canopy of the overstory May or may not be independent of surface fire
Photo Univ of Toronto Fier Lab
Photo News Provider
Spotting ndash burning or glowing embers being transported in the air
Torching ndash Movement of fire from the surface to the crowns of individual trees
Flare Up ndash A sudden increase in ROS and Intensity
Fuel Oxygen
Heat
The Fire TriangleThe Fire Triangle
Energy release in the form of heat and light when oxygen combines Energy release in the form of heat and light when oxygen combines with a combustible material (fuel) at a suitably high temperaturewith a combustible material (fuel) at a suitably high temperature
Photosynthesis converts radiant energy to stored chemical energy (CO2 + H2O ---light-----gt C6H12O6 + O2)
Combustion reverses photosynthesis(C6H12O6 + O2 ---high temperature-----gt H2O + CO2 + heat and light)
(fuel) (325 C for wood)
Same process as decay and decomposition Begins with endothermic reaction becomes exothermic Produces thermal radiant and kinetic energy
Extinction insufficient heat to sustain combustion
HEAT
WATER ampORGANICGASES
Pre-Ignition
VISIBLE SMOKE
Smoldering
CO CO2
Glowing
2CO WATER
VISIBLE SMOKE
Flaming
4 Phases of Combustion
Pre-ignition Requires heatenergy input to
increase surface temperature gt200˚C
Dehydration Volatilization of waxes oils other
extractives Pyrolysis (chemical decomposition of
organic matter without Oxygenndash inside fuels emits volatiles)
Volatiles either condense into particles (smoke) or are consumed during flaming combustion
HEAT
WATER ampORGANICGASES
Pre-Ignition
Ignition Transition to flaming
combustion gases released by pyrolysis ignite
Surface temperatures around 320 C (600F)
Heat released by combustion brings other fuels to ignition
Flaming combustion Surface temperatures 200- 500˚
C Combustible volatiles ignite
above surface creating flame the GASES are burning not the fuel itself
Combustion occurs in zone above fuel surface
Oxidation produces heat CO2 H2O and incompletely degraded organic compounds
Smoke includes these + other gases which condense or reform above flame zone
2CO WATER
VISIBLE SMOKE
Flaming
Smoldering No visible flames Surface temperatures lt 500 C Carbon buildup on surface reduces gas
production that would maintain flame Occurs when fuels tightly packed Surface char oxidizes to CO2 H2O ash Continued oxidation of other
compounds Smoldering duff and ground fires raise
soil temperature and can kill roots Large quantities of smoke
VISIBLE SMOKE
Smoldering
A result of incomplete combustion Major constituents
Particulate matter Solid or liquid particle suspended in
atmosphere Condensed hydrocarbons and tar
materials Entrained fragments of vegetation and
ash CO2 and CO H2O Gaseous hydrocarbons
Smokevolume burned increases for Low intensity fires in moist or living
fuels High rates of spread (amp less efficient
combustion)
CO CO2
GlowingbullAll volatiles have already been driven off oxygen reaches the combustion surfaces and there is no visible smoke (products are CO2 and CO)bullOxidation of solid fuel accompanied by incandescencebullThis phase follows smoldering combustion continues until temperature drops or only non-combustible ash remains
Radiation For example the sun and your handhellip Electromagnetic waves transfer heat to
fuel surface only
Accounts for most drying and heating of fuel surfaces ahead of flame or on opposite steep slopesndash radiates in all directions
Radiation For example the sun and your handhellipFor example the sun and your handhellip Electromagnetic waves transfer heat to fuel Electromagnetic waves transfer heat to fuel
surface onlysurface only
Accounts for most drying and heating of Accounts for most drying and heating of fuel surfaces ahead of flame or on opposite fuel surfaces ahead of flame or on opposite steep slopesndash radiates in all directionssteep slopesndash radiates in all directions
Convection Vertical (or other direction)
movement of gas or liquid as heat rises
Heats plant foliage above surface fires and fuels ahead of the flame on steep slopes or if wind driven
Carries firebrands away from fire spotting potential
Can create enormous columns and drive fire behavior
ConvectionConvection Vertical (or other direction) movement of Vertical (or other direction) movement of
gas or liquid as heat risesgas or liquid as heat rises Heats plant foliage above surface fires Heats plant foliage above surface fires
and fuels ahead of the flame on steep and fuels ahead of the flame on steep slopes or if wind drivenslopes or if wind driven
Carries firebrands away from fire Carries firebrands away from fire spotting potentialspotting potential
Can create enormous columns and drive Can create enormous columns and drive fire behaviorfire behavior
Heat Transfer ProcessesHeat Transfer Processes
ConductionConduction Transfer by molecular activity Transfer by molecular activity
withinwithin a solid object a solid object Primary method for raising Primary method for raising
temperatures within large fuelstemperatures within large fuels Occurs between objectsfuels Occurs between objectsfuels
that are in contactthat are in contact Transfers heat in dense fuels Transfers heat in dense fuels
requiring additional heat to reach requiring additional heat to reach ignitionignition
Rate of spread (ROS) rate at which fire front advances through forest fuel (ftsec chainsmin)
Residency Time Duration for flaming combustion to pass a specific location
Flame Length amp Depth
Residency Time = Flame DepthROS
Intensity ndash rate of heat energy during combustion Reaction intensity per unit area (BTUft-2min-1) Fireline Intensity per unit length of the fire front (BTUft-1min-
1)
I = hwr
I fireline intensityh fuel heat contentw weight of fuel consumed per unit arear rate of spread
Flame Length is a good estimate of intensity
Severity Impact of fire on the environment Plants animals soils water
SE
VE
RIT
Y
INTENSITY
LOW
HIGH
HIGHLOW
Backing fire in long unburned longleaf pine
Stand replacing fire in mixed conifer forests
Head fire in frequently burned longleaf pine
Chaparral Brush Fires
1 Weather
2 Fuels 3 Topography
Surface Fuels Grasses Shrubs Litter (leaves)
Woody debris
Ground Fuels Duff (partially
decomposed)
Peat Roots Stumps
mineral soil
litter
fermentation layerhumus
Duff
Aerial Fuels Crown or canopy of
overstory
Ladder Fuels (located between crown and surface fuels)
Smaller trees Vines
Size and Shape Surface areavolume
ratio Grasses Palmetto Branches Logs
10001
401
Particle Density
Fuel Chemistry Volatile oils
Mineral Content Dampening effect on
combustion
Heat Content (stored energy)
6000-12000 BTUlb
Fuel Arrangement Vertical Grasses amp shrubs
Horizontal Litter Downed woody debris
Fuel Loading By size classes
Compactness Bulk density (fuel loadfuelbed volume)
Packing ratio (fuelbed densityparticle density)
Continuity Vertical Horizontal
ALL FUELBED PROPERTIES
Fuel Moisture Content (FMC) Large dampening effect on
combustion Heat sink
FMC changes hourly daily and seasonally
Fuel Moisture Content () = (Water Weight Dry Fuel Weight) x 100
What influences FMC In Dead Fuels Precipitation (amount
and duration) Temperature Relative humidity Wind
Equilibrium Moisture Content For a given temperature and RH dead fuel
will reach a FMC at equilibrium Environmental conditions are not constant Fuel is constantly changes FMC to reach
EMC
The lag time to reach EMC depends on particle size
Timelag categories for dead woody fuels
Timelag Class Fuel Diameter
Timelag Range (hr)
1 Hour 0-14rdquo 0-2
10 Hour frac14rdquo-1rdquo 2-20
100 Hour 1-3rdquo 20-200
1000 Hour 3-8rdquo 200-2000
Timelag or ldquoresponse timerdquo is the time it takes for 63 of the change to occur between one EMC and a second EMC when a fuel in equilibrium with a stable environmental condition is suddenly exposed to a different stable environmental condition
Small diameter fuels react quickly to hourly and daily changes Important to monitor
Large diameter fuels react more to seasonal changes California versus Florida
Fine fuels drive fire behavior
Moisture of Extinction Dead 12-40 Live gt120
Available Fuel
Florida Fine Fuel Moisture Calculation Chart
httpwwwfl-dofcomwildfirerx_traininghtmlcbc
Live Fuels FMC can be much higher than dead
fuels (100-300) Influenced by Drought (KBDI) RH Wind
Ignition of live fuels may largely depend the combustion characteristics of other fuels (eg dead surface fuels)
Duff Moisture Very dry to very moist lt30 FMC duff can burn on its own Potential for tree mortality in
burning long unburned forests May smolder for long durations May cause lots of smoke
FMCWind
Increases O2 Bends flames Increases ROS Dries fuels
convectionwind
radiation
conduction
Slopes Similar effect as
wind Bends flames ROS higher
upslope
Slope Positiontop middle bottom
Aspect
Other topographic features Valleys Box Canyons Steep draws Elevation
ELEVATION
Indicators (on a Rx burn) KBDIgt500 FMC (fine) lt7 RHlt30 Cold front approaching Gusty winds Dust devilsfire whirls Just inland from seabreeze Well-defined convection column Thunderstorms Spotting DI approaching 70
Fire Behavior Prediction Models (eg BehavePlus)
INPUTS OUTPUTSFuel characteristics Rate of
SpreadFMC Fireline IntensitySlope Flame LengthsWind and morehellip
- Slide 9
- Slide 15
- Slide 46
-
CPBM Objectives (chapter 8)
6) Identify Fuel Models and examples in Florida
7) Explain the difference between fire intensity and severity and how both can be regulated and measured
8) Define residence time and why it is significant in Rx fire
9) Discuss indicators of erratic or potentially erratic fire behavior
Wind
REAR
LEFT
FLANK
RIGHT FLA
NK
FINGER
HEAD
SPOT FIRE
UNBURNED ISLAND
Surface Fire Burning in surface fuels Grass shrubs litter
Ground Fire Smoldering in ground fuels duff peat roots stumps
Crown Fire Burning in aerial fuels Crowns or canopy of the overstory May or may not be independent of surface fire
Photo Univ of Toronto Fier Lab
Photo News Provider
Spotting ndash burning or glowing embers being transported in the air
Torching ndash Movement of fire from the surface to the crowns of individual trees
Flare Up ndash A sudden increase in ROS and Intensity
Fuel Oxygen
Heat
The Fire TriangleThe Fire Triangle
Energy release in the form of heat and light when oxygen combines Energy release in the form of heat and light when oxygen combines with a combustible material (fuel) at a suitably high temperaturewith a combustible material (fuel) at a suitably high temperature
Photosynthesis converts radiant energy to stored chemical energy (CO2 + H2O ---light-----gt C6H12O6 + O2)
Combustion reverses photosynthesis(C6H12O6 + O2 ---high temperature-----gt H2O + CO2 + heat and light)
(fuel) (325 C for wood)
Same process as decay and decomposition Begins with endothermic reaction becomes exothermic Produces thermal radiant and kinetic energy
Extinction insufficient heat to sustain combustion
HEAT
WATER ampORGANICGASES
Pre-Ignition
VISIBLE SMOKE
Smoldering
CO CO2
Glowing
2CO WATER
VISIBLE SMOKE
Flaming
4 Phases of Combustion
Pre-ignition Requires heatenergy input to
increase surface temperature gt200˚C
Dehydration Volatilization of waxes oils other
extractives Pyrolysis (chemical decomposition of
organic matter without Oxygenndash inside fuels emits volatiles)
Volatiles either condense into particles (smoke) or are consumed during flaming combustion
HEAT
WATER ampORGANICGASES
Pre-Ignition
Ignition Transition to flaming
combustion gases released by pyrolysis ignite
Surface temperatures around 320 C (600F)
Heat released by combustion brings other fuels to ignition
Flaming combustion Surface temperatures 200- 500˚
C Combustible volatiles ignite
above surface creating flame the GASES are burning not the fuel itself
Combustion occurs in zone above fuel surface
Oxidation produces heat CO2 H2O and incompletely degraded organic compounds
Smoke includes these + other gases which condense or reform above flame zone
2CO WATER
VISIBLE SMOKE
Flaming
Smoldering No visible flames Surface temperatures lt 500 C Carbon buildup on surface reduces gas
production that would maintain flame Occurs when fuels tightly packed Surface char oxidizes to CO2 H2O ash Continued oxidation of other
compounds Smoldering duff and ground fires raise
soil temperature and can kill roots Large quantities of smoke
VISIBLE SMOKE
Smoldering
A result of incomplete combustion Major constituents
Particulate matter Solid or liquid particle suspended in
atmosphere Condensed hydrocarbons and tar
materials Entrained fragments of vegetation and
ash CO2 and CO H2O Gaseous hydrocarbons
Smokevolume burned increases for Low intensity fires in moist or living
fuels High rates of spread (amp less efficient
combustion)
CO CO2
GlowingbullAll volatiles have already been driven off oxygen reaches the combustion surfaces and there is no visible smoke (products are CO2 and CO)bullOxidation of solid fuel accompanied by incandescencebullThis phase follows smoldering combustion continues until temperature drops or only non-combustible ash remains
Radiation For example the sun and your handhellip Electromagnetic waves transfer heat to
fuel surface only
Accounts for most drying and heating of fuel surfaces ahead of flame or on opposite steep slopesndash radiates in all directions
Radiation For example the sun and your handhellipFor example the sun and your handhellip Electromagnetic waves transfer heat to fuel Electromagnetic waves transfer heat to fuel
surface onlysurface only
Accounts for most drying and heating of Accounts for most drying and heating of fuel surfaces ahead of flame or on opposite fuel surfaces ahead of flame or on opposite steep slopesndash radiates in all directionssteep slopesndash radiates in all directions
Convection Vertical (or other direction)
movement of gas or liquid as heat rises
Heats plant foliage above surface fires and fuels ahead of the flame on steep slopes or if wind driven
Carries firebrands away from fire spotting potential
Can create enormous columns and drive fire behavior
ConvectionConvection Vertical (or other direction) movement of Vertical (or other direction) movement of
gas or liquid as heat risesgas or liquid as heat rises Heats plant foliage above surface fires Heats plant foliage above surface fires
and fuels ahead of the flame on steep and fuels ahead of the flame on steep slopes or if wind drivenslopes or if wind driven
Carries firebrands away from fire Carries firebrands away from fire spotting potentialspotting potential
Can create enormous columns and drive Can create enormous columns and drive fire behaviorfire behavior
Heat Transfer ProcessesHeat Transfer Processes
ConductionConduction Transfer by molecular activity Transfer by molecular activity
withinwithin a solid object a solid object Primary method for raising Primary method for raising
temperatures within large fuelstemperatures within large fuels Occurs between objectsfuels Occurs between objectsfuels
that are in contactthat are in contact Transfers heat in dense fuels Transfers heat in dense fuels
requiring additional heat to reach requiring additional heat to reach ignitionignition
Rate of spread (ROS) rate at which fire front advances through forest fuel (ftsec chainsmin)
Residency Time Duration for flaming combustion to pass a specific location
Flame Length amp Depth
Residency Time = Flame DepthROS
Intensity ndash rate of heat energy during combustion Reaction intensity per unit area (BTUft-2min-1) Fireline Intensity per unit length of the fire front (BTUft-1min-
1)
I = hwr
I fireline intensityh fuel heat contentw weight of fuel consumed per unit arear rate of spread
Flame Length is a good estimate of intensity
Severity Impact of fire on the environment Plants animals soils water
SE
VE
RIT
Y
INTENSITY
LOW
HIGH
HIGHLOW
Backing fire in long unburned longleaf pine
Stand replacing fire in mixed conifer forests
Head fire in frequently burned longleaf pine
Chaparral Brush Fires
1 Weather
2 Fuels 3 Topography
Surface Fuels Grasses Shrubs Litter (leaves)
Woody debris
Ground Fuels Duff (partially
decomposed)
Peat Roots Stumps
mineral soil
litter
fermentation layerhumus
Duff
Aerial Fuels Crown or canopy of
overstory
Ladder Fuels (located between crown and surface fuels)
Smaller trees Vines
Size and Shape Surface areavolume
ratio Grasses Palmetto Branches Logs
10001
401
Particle Density
Fuel Chemistry Volatile oils
Mineral Content Dampening effect on
combustion
Heat Content (stored energy)
6000-12000 BTUlb
Fuel Arrangement Vertical Grasses amp shrubs
Horizontal Litter Downed woody debris
Fuel Loading By size classes
Compactness Bulk density (fuel loadfuelbed volume)
Packing ratio (fuelbed densityparticle density)
Continuity Vertical Horizontal
ALL FUELBED PROPERTIES
Fuel Moisture Content (FMC) Large dampening effect on
combustion Heat sink
FMC changes hourly daily and seasonally
Fuel Moisture Content () = (Water Weight Dry Fuel Weight) x 100
What influences FMC In Dead Fuels Precipitation (amount
and duration) Temperature Relative humidity Wind
Equilibrium Moisture Content For a given temperature and RH dead fuel
will reach a FMC at equilibrium Environmental conditions are not constant Fuel is constantly changes FMC to reach
EMC
The lag time to reach EMC depends on particle size
Timelag categories for dead woody fuels
Timelag Class Fuel Diameter
Timelag Range (hr)
1 Hour 0-14rdquo 0-2
10 Hour frac14rdquo-1rdquo 2-20
100 Hour 1-3rdquo 20-200
1000 Hour 3-8rdquo 200-2000
Timelag or ldquoresponse timerdquo is the time it takes for 63 of the change to occur between one EMC and a second EMC when a fuel in equilibrium with a stable environmental condition is suddenly exposed to a different stable environmental condition
Small diameter fuels react quickly to hourly and daily changes Important to monitor
Large diameter fuels react more to seasonal changes California versus Florida
Fine fuels drive fire behavior
Moisture of Extinction Dead 12-40 Live gt120
Available Fuel
Florida Fine Fuel Moisture Calculation Chart
httpwwwfl-dofcomwildfirerx_traininghtmlcbc
Live Fuels FMC can be much higher than dead
fuels (100-300) Influenced by Drought (KBDI) RH Wind
Ignition of live fuels may largely depend the combustion characteristics of other fuels (eg dead surface fuels)
Duff Moisture Very dry to very moist lt30 FMC duff can burn on its own Potential for tree mortality in
burning long unburned forests May smolder for long durations May cause lots of smoke
FMCWind
Increases O2 Bends flames Increases ROS Dries fuels
convectionwind
radiation
conduction
Slopes Similar effect as
wind Bends flames ROS higher
upslope
Slope Positiontop middle bottom
Aspect
Other topographic features Valleys Box Canyons Steep draws Elevation
ELEVATION
Indicators (on a Rx burn) KBDIgt500 FMC (fine) lt7 RHlt30 Cold front approaching Gusty winds Dust devilsfire whirls Just inland from seabreeze Well-defined convection column Thunderstorms Spotting DI approaching 70
Fire Behavior Prediction Models (eg BehavePlus)
INPUTS OUTPUTSFuel characteristics Rate of
SpreadFMC Fireline IntensitySlope Flame LengthsWind and morehellip
- Slide 9
- Slide 15
- Slide 46
-
Wind
REAR
LEFT
FLANK
RIGHT FLA
NK
FINGER
HEAD
SPOT FIRE
UNBURNED ISLAND
Surface Fire Burning in surface fuels Grass shrubs litter
Ground Fire Smoldering in ground fuels duff peat roots stumps
Crown Fire Burning in aerial fuels Crowns or canopy of the overstory May or may not be independent of surface fire
Photo Univ of Toronto Fier Lab
Photo News Provider
Spotting ndash burning or glowing embers being transported in the air
Torching ndash Movement of fire from the surface to the crowns of individual trees
Flare Up ndash A sudden increase in ROS and Intensity
Fuel Oxygen
Heat
The Fire TriangleThe Fire Triangle
Energy release in the form of heat and light when oxygen combines Energy release in the form of heat and light when oxygen combines with a combustible material (fuel) at a suitably high temperaturewith a combustible material (fuel) at a suitably high temperature
Photosynthesis converts radiant energy to stored chemical energy (CO2 + H2O ---light-----gt C6H12O6 + O2)
Combustion reverses photosynthesis(C6H12O6 + O2 ---high temperature-----gt H2O + CO2 + heat and light)
(fuel) (325 C for wood)
Same process as decay and decomposition Begins with endothermic reaction becomes exothermic Produces thermal radiant and kinetic energy
Extinction insufficient heat to sustain combustion
HEAT
WATER ampORGANICGASES
Pre-Ignition
VISIBLE SMOKE
Smoldering
CO CO2
Glowing
2CO WATER
VISIBLE SMOKE
Flaming
4 Phases of Combustion
Pre-ignition Requires heatenergy input to
increase surface temperature gt200˚C
Dehydration Volatilization of waxes oils other
extractives Pyrolysis (chemical decomposition of
organic matter without Oxygenndash inside fuels emits volatiles)
Volatiles either condense into particles (smoke) or are consumed during flaming combustion
HEAT
WATER ampORGANICGASES
Pre-Ignition
Ignition Transition to flaming
combustion gases released by pyrolysis ignite
Surface temperatures around 320 C (600F)
Heat released by combustion brings other fuels to ignition
Flaming combustion Surface temperatures 200- 500˚
C Combustible volatiles ignite
above surface creating flame the GASES are burning not the fuel itself
Combustion occurs in zone above fuel surface
Oxidation produces heat CO2 H2O and incompletely degraded organic compounds
Smoke includes these + other gases which condense or reform above flame zone
2CO WATER
VISIBLE SMOKE
Flaming
Smoldering No visible flames Surface temperatures lt 500 C Carbon buildup on surface reduces gas
production that would maintain flame Occurs when fuels tightly packed Surface char oxidizes to CO2 H2O ash Continued oxidation of other
compounds Smoldering duff and ground fires raise
soil temperature and can kill roots Large quantities of smoke
VISIBLE SMOKE
Smoldering
A result of incomplete combustion Major constituents
Particulate matter Solid or liquid particle suspended in
atmosphere Condensed hydrocarbons and tar
materials Entrained fragments of vegetation and
ash CO2 and CO H2O Gaseous hydrocarbons
Smokevolume burned increases for Low intensity fires in moist or living
fuels High rates of spread (amp less efficient
combustion)
CO CO2
GlowingbullAll volatiles have already been driven off oxygen reaches the combustion surfaces and there is no visible smoke (products are CO2 and CO)bullOxidation of solid fuel accompanied by incandescencebullThis phase follows smoldering combustion continues until temperature drops or only non-combustible ash remains
Radiation For example the sun and your handhellip Electromagnetic waves transfer heat to
fuel surface only
Accounts for most drying and heating of fuel surfaces ahead of flame or on opposite steep slopesndash radiates in all directions
Radiation For example the sun and your handhellipFor example the sun and your handhellip Electromagnetic waves transfer heat to fuel Electromagnetic waves transfer heat to fuel
surface onlysurface only
Accounts for most drying and heating of Accounts for most drying and heating of fuel surfaces ahead of flame or on opposite fuel surfaces ahead of flame or on opposite steep slopesndash radiates in all directionssteep slopesndash radiates in all directions
Convection Vertical (or other direction)
movement of gas or liquid as heat rises
Heats plant foliage above surface fires and fuels ahead of the flame on steep slopes or if wind driven
Carries firebrands away from fire spotting potential
Can create enormous columns and drive fire behavior
ConvectionConvection Vertical (or other direction) movement of Vertical (or other direction) movement of
gas or liquid as heat risesgas or liquid as heat rises Heats plant foliage above surface fires Heats plant foliage above surface fires
and fuels ahead of the flame on steep and fuels ahead of the flame on steep slopes or if wind drivenslopes or if wind driven
Carries firebrands away from fire Carries firebrands away from fire spotting potentialspotting potential
Can create enormous columns and drive Can create enormous columns and drive fire behaviorfire behavior
Heat Transfer ProcessesHeat Transfer Processes
ConductionConduction Transfer by molecular activity Transfer by molecular activity
withinwithin a solid object a solid object Primary method for raising Primary method for raising
temperatures within large fuelstemperatures within large fuels Occurs between objectsfuels Occurs between objectsfuels
that are in contactthat are in contact Transfers heat in dense fuels Transfers heat in dense fuels
requiring additional heat to reach requiring additional heat to reach ignitionignition
Rate of spread (ROS) rate at which fire front advances through forest fuel (ftsec chainsmin)
Residency Time Duration for flaming combustion to pass a specific location
Flame Length amp Depth
Residency Time = Flame DepthROS
Intensity ndash rate of heat energy during combustion Reaction intensity per unit area (BTUft-2min-1) Fireline Intensity per unit length of the fire front (BTUft-1min-
1)
I = hwr
I fireline intensityh fuel heat contentw weight of fuel consumed per unit arear rate of spread
Flame Length is a good estimate of intensity
Severity Impact of fire on the environment Plants animals soils water
SE
VE
RIT
Y
INTENSITY
LOW
HIGH
HIGHLOW
Backing fire in long unburned longleaf pine
Stand replacing fire in mixed conifer forests
Head fire in frequently burned longleaf pine
Chaparral Brush Fires
1 Weather
2 Fuels 3 Topography
Surface Fuels Grasses Shrubs Litter (leaves)
Woody debris
Ground Fuels Duff (partially
decomposed)
Peat Roots Stumps
mineral soil
litter
fermentation layerhumus
Duff
Aerial Fuels Crown or canopy of
overstory
Ladder Fuels (located between crown and surface fuels)
Smaller trees Vines
Size and Shape Surface areavolume
ratio Grasses Palmetto Branches Logs
10001
401
Particle Density
Fuel Chemistry Volatile oils
Mineral Content Dampening effect on
combustion
Heat Content (stored energy)
6000-12000 BTUlb
Fuel Arrangement Vertical Grasses amp shrubs
Horizontal Litter Downed woody debris
Fuel Loading By size classes
Compactness Bulk density (fuel loadfuelbed volume)
Packing ratio (fuelbed densityparticle density)
Continuity Vertical Horizontal
ALL FUELBED PROPERTIES
Fuel Moisture Content (FMC) Large dampening effect on
combustion Heat sink
FMC changes hourly daily and seasonally
Fuel Moisture Content () = (Water Weight Dry Fuel Weight) x 100
What influences FMC In Dead Fuels Precipitation (amount
and duration) Temperature Relative humidity Wind
Equilibrium Moisture Content For a given temperature and RH dead fuel
will reach a FMC at equilibrium Environmental conditions are not constant Fuel is constantly changes FMC to reach
EMC
The lag time to reach EMC depends on particle size
Timelag categories for dead woody fuels
Timelag Class Fuel Diameter
Timelag Range (hr)
1 Hour 0-14rdquo 0-2
10 Hour frac14rdquo-1rdquo 2-20
100 Hour 1-3rdquo 20-200
1000 Hour 3-8rdquo 200-2000
Timelag or ldquoresponse timerdquo is the time it takes for 63 of the change to occur between one EMC and a second EMC when a fuel in equilibrium with a stable environmental condition is suddenly exposed to a different stable environmental condition
Small diameter fuels react quickly to hourly and daily changes Important to monitor
Large diameter fuels react more to seasonal changes California versus Florida
Fine fuels drive fire behavior
Moisture of Extinction Dead 12-40 Live gt120
Available Fuel
Florida Fine Fuel Moisture Calculation Chart
httpwwwfl-dofcomwildfirerx_traininghtmlcbc
Live Fuels FMC can be much higher than dead
fuels (100-300) Influenced by Drought (KBDI) RH Wind
Ignition of live fuels may largely depend the combustion characteristics of other fuels (eg dead surface fuels)
Duff Moisture Very dry to very moist lt30 FMC duff can burn on its own Potential for tree mortality in
burning long unburned forests May smolder for long durations May cause lots of smoke
FMCWind
Increases O2 Bends flames Increases ROS Dries fuels
convectionwind
radiation
conduction
Slopes Similar effect as
wind Bends flames ROS higher
upslope
Slope Positiontop middle bottom
Aspect
Other topographic features Valleys Box Canyons Steep draws Elevation
ELEVATION
Indicators (on a Rx burn) KBDIgt500 FMC (fine) lt7 RHlt30 Cold front approaching Gusty winds Dust devilsfire whirls Just inland from seabreeze Well-defined convection column Thunderstorms Spotting DI approaching 70
Fire Behavior Prediction Models (eg BehavePlus)
INPUTS OUTPUTSFuel characteristics Rate of
SpreadFMC Fireline IntensitySlope Flame LengthsWind and morehellip
- Slide 9
- Slide 15
- Slide 46
-
Surface Fire Burning in surface fuels Grass shrubs litter
Ground Fire Smoldering in ground fuels duff peat roots stumps
Crown Fire Burning in aerial fuels Crowns or canopy of the overstory May or may not be independent of surface fire
Photo Univ of Toronto Fier Lab
Photo News Provider
Spotting ndash burning or glowing embers being transported in the air
Torching ndash Movement of fire from the surface to the crowns of individual trees
Flare Up ndash A sudden increase in ROS and Intensity
Fuel Oxygen
Heat
The Fire TriangleThe Fire Triangle
Energy release in the form of heat and light when oxygen combines Energy release in the form of heat and light when oxygen combines with a combustible material (fuel) at a suitably high temperaturewith a combustible material (fuel) at a suitably high temperature
Photosynthesis converts radiant energy to stored chemical energy (CO2 + H2O ---light-----gt C6H12O6 + O2)
Combustion reverses photosynthesis(C6H12O6 + O2 ---high temperature-----gt H2O + CO2 + heat and light)
(fuel) (325 C for wood)
Same process as decay and decomposition Begins with endothermic reaction becomes exothermic Produces thermal radiant and kinetic energy
Extinction insufficient heat to sustain combustion
HEAT
WATER ampORGANICGASES
Pre-Ignition
VISIBLE SMOKE
Smoldering
CO CO2
Glowing
2CO WATER
VISIBLE SMOKE
Flaming
4 Phases of Combustion
Pre-ignition Requires heatenergy input to
increase surface temperature gt200˚C
Dehydration Volatilization of waxes oils other
extractives Pyrolysis (chemical decomposition of
organic matter without Oxygenndash inside fuels emits volatiles)
Volatiles either condense into particles (smoke) or are consumed during flaming combustion
HEAT
WATER ampORGANICGASES
Pre-Ignition
Ignition Transition to flaming
combustion gases released by pyrolysis ignite
Surface temperatures around 320 C (600F)
Heat released by combustion brings other fuels to ignition
Flaming combustion Surface temperatures 200- 500˚
C Combustible volatiles ignite
above surface creating flame the GASES are burning not the fuel itself
Combustion occurs in zone above fuel surface
Oxidation produces heat CO2 H2O and incompletely degraded organic compounds
Smoke includes these + other gases which condense or reform above flame zone
2CO WATER
VISIBLE SMOKE
Flaming
Smoldering No visible flames Surface temperatures lt 500 C Carbon buildup on surface reduces gas
production that would maintain flame Occurs when fuels tightly packed Surface char oxidizes to CO2 H2O ash Continued oxidation of other
compounds Smoldering duff and ground fires raise
soil temperature and can kill roots Large quantities of smoke
VISIBLE SMOKE
Smoldering
A result of incomplete combustion Major constituents
Particulate matter Solid or liquid particle suspended in
atmosphere Condensed hydrocarbons and tar
materials Entrained fragments of vegetation and
ash CO2 and CO H2O Gaseous hydrocarbons
Smokevolume burned increases for Low intensity fires in moist or living
fuels High rates of spread (amp less efficient
combustion)
CO CO2
GlowingbullAll volatiles have already been driven off oxygen reaches the combustion surfaces and there is no visible smoke (products are CO2 and CO)bullOxidation of solid fuel accompanied by incandescencebullThis phase follows smoldering combustion continues until temperature drops or only non-combustible ash remains
Radiation For example the sun and your handhellip Electromagnetic waves transfer heat to
fuel surface only
Accounts for most drying and heating of fuel surfaces ahead of flame or on opposite steep slopesndash radiates in all directions
Radiation For example the sun and your handhellipFor example the sun and your handhellip Electromagnetic waves transfer heat to fuel Electromagnetic waves transfer heat to fuel
surface onlysurface only
Accounts for most drying and heating of Accounts for most drying and heating of fuel surfaces ahead of flame or on opposite fuel surfaces ahead of flame or on opposite steep slopesndash radiates in all directionssteep slopesndash radiates in all directions
Convection Vertical (or other direction)
movement of gas or liquid as heat rises
Heats plant foliage above surface fires and fuels ahead of the flame on steep slopes or if wind driven
Carries firebrands away from fire spotting potential
Can create enormous columns and drive fire behavior
ConvectionConvection Vertical (or other direction) movement of Vertical (or other direction) movement of
gas or liquid as heat risesgas or liquid as heat rises Heats plant foliage above surface fires Heats plant foliage above surface fires
and fuels ahead of the flame on steep and fuels ahead of the flame on steep slopes or if wind drivenslopes or if wind driven
Carries firebrands away from fire Carries firebrands away from fire spotting potentialspotting potential
Can create enormous columns and drive Can create enormous columns and drive fire behaviorfire behavior
Heat Transfer ProcessesHeat Transfer Processes
ConductionConduction Transfer by molecular activity Transfer by molecular activity
withinwithin a solid object a solid object Primary method for raising Primary method for raising
temperatures within large fuelstemperatures within large fuels Occurs between objectsfuels Occurs between objectsfuels
that are in contactthat are in contact Transfers heat in dense fuels Transfers heat in dense fuels
requiring additional heat to reach requiring additional heat to reach ignitionignition
Rate of spread (ROS) rate at which fire front advances through forest fuel (ftsec chainsmin)
Residency Time Duration for flaming combustion to pass a specific location
Flame Length amp Depth
Residency Time = Flame DepthROS
Intensity ndash rate of heat energy during combustion Reaction intensity per unit area (BTUft-2min-1) Fireline Intensity per unit length of the fire front (BTUft-1min-
1)
I = hwr
I fireline intensityh fuel heat contentw weight of fuel consumed per unit arear rate of spread
Flame Length is a good estimate of intensity
Severity Impact of fire on the environment Plants animals soils water
SE
VE
RIT
Y
INTENSITY
LOW
HIGH
HIGHLOW
Backing fire in long unburned longleaf pine
Stand replacing fire in mixed conifer forests
Head fire in frequently burned longleaf pine
Chaparral Brush Fires
1 Weather
2 Fuels 3 Topography
Surface Fuels Grasses Shrubs Litter (leaves)
Woody debris
Ground Fuels Duff (partially
decomposed)
Peat Roots Stumps
mineral soil
litter
fermentation layerhumus
Duff
Aerial Fuels Crown or canopy of
overstory
Ladder Fuels (located between crown and surface fuels)
Smaller trees Vines
Size and Shape Surface areavolume
ratio Grasses Palmetto Branches Logs
10001
401
Particle Density
Fuel Chemistry Volatile oils
Mineral Content Dampening effect on
combustion
Heat Content (stored energy)
6000-12000 BTUlb
Fuel Arrangement Vertical Grasses amp shrubs
Horizontal Litter Downed woody debris
Fuel Loading By size classes
Compactness Bulk density (fuel loadfuelbed volume)
Packing ratio (fuelbed densityparticle density)
Continuity Vertical Horizontal
ALL FUELBED PROPERTIES
Fuel Moisture Content (FMC) Large dampening effect on
combustion Heat sink
FMC changes hourly daily and seasonally
Fuel Moisture Content () = (Water Weight Dry Fuel Weight) x 100
What influences FMC In Dead Fuels Precipitation (amount
and duration) Temperature Relative humidity Wind
Equilibrium Moisture Content For a given temperature and RH dead fuel
will reach a FMC at equilibrium Environmental conditions are not constant Fuel is constantly changes FMC to reach
EMC
The lag time to reach EMC depends on particle size
Timelag categories for dead woody fuels
Timelag Class Fuel Diameter
Timelag Range (hr)
1 Hour 0-14rdquo 0-2
10 Hour frac14rdquo-1rdquo 2-20
100 Hour 1-3rdquo 20-200
1000 Hour 3-8rdquo 200-2000
Timelag or ldquoresponse timerdquo is the time it takes for 63 of the change to occur between one EMC and a second EMC when a fuel in equilibrium with a stable environmental condition is suddenly exposed to a different stable environmental condition
Small diameter fuels react quickly to hourly and daily changes Important to monitor
Large diameter fuels react more to seasonal changes California versus Florida
Fine fuels drive fire behavior
Moisture of Extinction Dead 12-40 Live gt120
Available Fuel
Florida Fine Fuel Moisture Calculation Chart
httpwwwfl-dofcomwildfirerx_traininghtmlcbc
Live Fuels FMC can be much higher than dead
fuels (100-300) Influenced by Drought (KBDI) RH Wind
Ignition of live fuels may largely depend the combustion characteristics of other fuels (eg dead surface fuels)
Duff Moisture Very dry to very moist lt30 FMC duff can burn on its own Potential for tree mortality in
burning long unburned forests May smolder for long durations May cause lots of smoke
FMCWind
Increases O2 Bends flames Increases ROS Dries fuels
convectionwind
radiation
conduction
Slopes Similar effect as
wind Bends flames ROS higher
upslope
Slope Positiontop middle bottom
Aspect
Other topographic features Valleys Box Canyons Steep draws Elevation
ELEVATION
Indicators (on a Rx burn) KBDIgt500 FMC (fine) lt7 RHlt30 Cold front approaching Gusty winds Dust devilsfire whirls Just inland from seabreeze Well-defined convection column Thunderstorms Spotting DI approaching 70
Fire Behavior Prediction Models (eg BehavePlus)
INPUTS OUTPUTSFuel characteristics Rate of
SpreadFMC Fireline IntensitySlope Flame LengthsWind and morehellip
- Slide 9
- Slide 15
- Slide 46
-
Spotting ndash burning or glowing embers being transported in the air
Torching ndash Movement of fire from the surface to the crowns of individual trees
Flare Up ndash A sudden increase in ROS and Intensity
Fuel Oxygen
Heat
The Fire TriangleThe Fire Triangle
Energy release in the form of heat and light when oxygen combines Energy release in the form of heat and light when oxygen combines with a combustible material (fuel) at a suitably high temperaturewith a combustible material (fuel) at a suitably high temperature
Photosynthesis converts radiant energy to stored chemical energy (CO2 + H2O ---light-----gt C6H12O6 + O2)
Combustion reverses photosynthesis(C6H12O6 + O2 ---high temperature-----gt H2O + CO2 + heat and light)
(fuel) (325 C for wood)
Same process as decay and decomposition Begins with endothermic reaction becomes exothermic Produces thermal radiant and kinetic energy
Extinction insufficient heat to sustain combustion
HEAT
WATER ampORGANICGASES
Pre-Ignition
VISIBLE SMOKE
Smoldering
CO CO2
Glowing
2CO WATER
VISIBLE SMOKE
Flaming
4 Phases of Combustion
Pre-ignition Requires heatenergy input to
increase surface temperature gt200˚C
Dehydration Volatilization of waxes oils other
extractives Pyrolysis (chemical decomposition of
organic matter without Oxygenndash inside fuels emits volatiles)
Volatiles either condense into particles (smoke) or are consumed during flaming combustion
HEAT
WATER ampORGANICGASES
Pre-Ignition
Ignition Transition to flaming
combustion gases released by pyrolysis ignite
Surface temperatures around 320 C (600F)
Heat released by combustion brings other fuels to ignition
Flaming combustion Surface temperatures 200- 500˚
C Combustible volatiles ignite
above surface creating flame the GASES are burning not the fuel itself
Combustion occurs in zone above fuel surface
Oxidation produces heat CO2 H2O and incompletely degraded organic compounds
Smoke includes these + other gases which condense or reform above flame zone
2CO WATER
VISIBLE SMOKE
Flaming
Smoldering No visible flames Surface temperatures lt 500 C Carbon buildup on surface reduces gas
production that would maintain flame Occurs when fuels tightly packed Surface char oxidizes to CO2 H2O ash Continued oxidation of other
compounds Smoldering duff and ground fires raise
soil temperature and can kill roots Large quantities of smoke
VISIBLE SMOKE
Smoldering
A result of incomplete combustion Major constituents
Particulate matter Solid or liquid particle suspended in
atmosphere Condensed hydrocarbons and tar
materials Entrained fragments of vegetation and
ash CO2 and CO H2O Gaseous hydrocarbons
Smokevolume burned increases for Low intensity fires in moist or living
fuels High rates of spread (amp less efficient
combustion)
CO CO2
GlowingbullAll volatiles have already been driven off oxygen reaches the combustion surfaces and there is no visible smoke (products are CO2 and CO)bullOxidation of solid fuel accompanied by incandescencebullThis phase follows smoldering combustion continues until temperature drops or only non-combustible ash remains
Radiation For example the sun and your handhellip Electromagnetic waves transfer heat to
fuel surface only
Accounts for most drying and heating of fuel surfaces ahead of flame or on opposite steep slopesndash radiates in all directions
Radiation For example the sun and your handhellipFor example the sun and your handhellip Electromagnetic waves transfer heat to fuel Electromagnetic waves transfer heat to fuel
surface onlysurface only
Accounts for most drying and heating of Accounts for most drying and heating of fuel surfaces ahead of flame or on opposite fuel surfaces ahead of flame or on opposite steep slopesndash radiates in all directionssteep slopesndash radiates in all directions
Convection Vertical (or other direction)
movement of gas or liquid as heat rises
Heats plant foliage above surface fires and fuels ahead of the flame on steep slopes or if wind driven
Carries firebrands away from fire spotting potential
Can create enormous columns and drive fire behavior
ConvectionConvection Vertical (or other direction) movement of Vertical (or other direction) movement of
gas or liquid as heat risesgas or liquid as heat rises Heats plant foliage above surface fires Heats plant foliage above surface fires
and fuels ahead of the flame on steep and fuels ahead of the flame on steep slopes or if wind drivenslopes or if wind driven
Carries firebrands away from fire Carries firebrands away from fire spotting potentialspotting potential
Can create enormous columns and drive Can create enormous columns and drive fire behaviorfire behavior
Heat Transfer ProcessesHeat Transfer Processes
ConductionConduction Transfer by molecular activity Transfer by molecular activity
withinwithin a solid object a solid object Primary method for raising Primary method for raising
temperatures within large fuelstemperatures within large fuels Occurs between objectsfuels Occurs between objectsfuels
that are in contactthat are in contact Transfers heat in dense fuels Transfers heat in dense fuels
requiring additional heat to reach requiring additional heat to reach ignitionignition
Rate of spread (ROS) rate at which fire front advances through forest fuel (ftsec chainsmin)
Residency Time Duration for flaming combustion to pass a specific location
Flame Length amp Depth
Residency Time = Flame DepthROS
Intensity ndash rate of heat energy during combustion Reaction intensity per unit area (BTUft-2min-1) Fireline Intensity per unit length of the fire front (BTUft-1min-
1)
I = hwr
I fireline intensityh fuel heat contentw weight of fuel consumed per unit arear rate of spread
Flame Length is a good estimate of intensity
Severity Impact of fire on the environment Plants animals soils water
SE
VE
RIT
Y
INTENSITY
LOW
HIGH
HIGHLOW
Backing fire in long unburned longleaf pine
Stand replacing fire in mixed conifer forests
Head fire in frequently burned longleaf pine
Chaparral Brush Fires
1 Weather
2 Fuels 3 Topography
Surface Fuels Grasses Shrubs Litter (leaves)
Woody debris
Ground Fuels Duff (partially
decomposed)
Peat Roots Stumps
mineral soil
litter
fermentation layerhumus
Duff
Aerial Fuels Crown or canopy of
overstory
Ladder Fuels (located between crown and surface fuels)
Smaller trees Vines
Size and Shape Surface areavolume
ratio Grasses Palmetto Branches Logs
10001
401
Particle Density
Fuel Chemistry Volatile oils
Mineral Content Dampening effect on
combustion
Heat Content (stored energy)
6000-12000 BTUlb
Fuel Arrangement Vertical Grasses amp shrubs
Horizontal Litter Downed woody debris
Fuel Loading By size classes
Compactness Bulk density (fuel loadfuelbed volume)
Packing ratio (fuelbed densityparticle density)
Continuity Vertical Horizontal
ALL FUELBED PROPERTIES
Fuel Moisture Content (FMC) Large dampening effect on
combustion Heat sink
FMC changes hourly daily and seasonally
Fuel Moisture Content () = (Water Weight Dry Fuel Weight) x 100
What influences FMC In Dead Fuels Precipitation (amount
and duration) Temperature Relative humidity Wind
Equilibrium Moisture Content For a given temperature and RH dead fuel
will reach a FMC at equilibrium Environmental conditions are not constant Fuel is constantly changes FMC to reach
EMC
The lag time to reach EMC depends on particle size
Timelag categories for dead woody fuels
Timelag Class Fuel Diameter
Timelag Range (hr)
1 Hour 0-14rdquo 0-2
10 Hour frac14rdquo-1rdquo 2-20
100 Hour 1-3rdquo 20-200
1000 Hour 3-8rdquo 200-2000
Timelag or ldquoresponse timerdquo is the time it takes for 63 of the change to occur between one EMC and a second EMC when a fuel in equilibrium with a stable environmental condition is suddenly exposed to a different stable environmental condition
Small diameter fuels react quickly to hourly and daily changes Important to monitor
Large diameter fuels react more to seasonal changes California versus Florida
Fine fuels drive fire behavior
Moisture of Extinction Dead 12-40 Live gt120
Available Fuel
Florida Fine Fuel Moisture Calculation Chart
httpwwwfl-dofcomwildfirerx_traininghtmlcbc
Live Fuels FMC can be much higher than dead
fuels (100-300) Influenced by Drought (KBDI) RH Wind
Ignition of live fuels may largely depend the combustion characteristics of other fuels (eg dead surface fuels)
Duff Moisture Very dry to very moist lt30 FMC duff can burn on its own Potential for tree mortality in
burning long unburned forests May smolder for long durations May cause lots of smoke
FMCWind
Increases O2 Bends flames Increases ROS Dries fuels
convectionwind
radiation
conduction
Slopes Similar effect as
wind Bends flames ROS higher
upslope
Slope Positiontop middle bottom
Aspect
Other topographic features Valleys Box Canyons Steep draws Elevation
ELEVATION
Indicators (on a Rx burn) KBDIgt500 FMC (fine) lt7 RHlt30 Cold front approaching Gusty winds Dust devilsfire whirls Just inland from seabreeze Well-defined convection column Thunderstorms Spotting DI approaching 70
Fire Behavior Prediction Models (eg BehavePlus)
INPUTS OUTPUTSFuel characteristics Rate of
SpreadFMC Fireline IntensitySlope Flame LengthsWind and morehellip
- Slide 9
- Slide 15
- Slide 46
-
Fuel Oxygen
Heat
The Fire TriangleThe Fire Triangle
Energy release in the form of heat and light when oxygen combines Energy release in the form of heat and light when oxygen combines with a combustible material (fuel) at a suitably high temperaturewith a combustible material (fuel) at a suitably high temperature
Photosynthesis converts radiant energy to stored chemical energy (CO2 + H2O ---light-----gt C6H12O6 + O2)
Combustion reverses photosynthesis(C6H12O6 + O2 ---high temperature-----gt H2O + CO2 + heat and light)
(fuel) (325 C for wood)
Same process as decay and decomposition Begins with endothermic reaction becomes exothermic Produces thermal radiant and kinetic energy
Extinction insufficient heat to sustain combustion
HEAT
WATER ampORGANICGASES
Pre-Ignition
VISIBLE SMOKE
Smoldering
CO CO2
Glowing
2CO WATER
VISIBLE SMOKE
Flaming
4 Phases of Combustion
Pre-ignition Requires heatenergy input to
increase surface temperature gt200˚C
Dehydration Volatilization of waxes oils other
extractives Pyrolysis (chemical decomposition of
organic matter without Oxygenndash inside fuels emits volatiles)
Volatiles either condense into particles (smoke) or are consumed during flaming combustion
HEAT
WATER ampORGANICGASES
Pre-Ignition
Ignition Transition to flaming
combustion gases released by pyrolysis ignite
Surface temperatures around 320 C (600F)
Heat released by combustion brings other fuels to ignition
Flaming combustion Surface temperatures 200- 500˚
C Combustible volatiles ignite
above surface creating flame the GASES are burning not the fuel itself
Combustion occurs in zone above fuel surface
Oxidation produces heat CO2 H2O and incompletely degraded organic compounds
Smoke includes these + other gases which condense or reform above flame zone
2CO WATER
VISIBLE SMOKE
Flaming
Smoldering No visible flames Surface temperatures lt 500 C Carbon buildup on surface reduces gas
production that would maintain flame Occurs when fuels tightly packed Surface char oxidizes to CO2 H2O ash Continued oxidation of other
compounds Smoldering duff and ground fires raise
soil temperature and can kill roots Large quantities of smoke
VISIBLE SMOKE
Smoldering
A result of incomplete combustion Major constituents
Particulate matter Solid or liquid particle suspended in
atmosphere Condensed hydrocarbons and tar
materials Entrained fragments of vegetation and
ash CO2 and CO H2O Gaseous hydrocarbons
Smokevolume burned increases for Low intensity fires in moist or living
fuels High rates of spread (amp less efficient
combustion)
CO CO2
GlowingbullAll volatiles have already been driven off oxygen reaches the combustion surfaces and there is no visible smoke (products are CO2 and CO)bullOxidation of solid fuel accompanied by incandescencebullThis phase follows smoldering combustion continues until temperature drops or only non-combustible ash remains
Radiation For example the sun and your handhellip Electromagnetic waves transfer heat to
fuel surface only
Accounts for most drying and heating of fuel surfaces ahead of flame or on opposite steep slopesndash radiates in all directions
Radiation For example the sun and your handhellipFor example the sun and your handhellip Electromagnetic waves transfer heat to fuel Electromagnetic waves transfer heat to fuel
surface onlysurface only
Accounts for most drying and heating of Accounts for most drying and heating of fuel surfaces ahead of flame or on opposite fuel surfaces ahead of flame or on opposite steep slopesndash radiates in all directionssteep slopesndash radiates in all directions
Convection Vertical (or other direction)
movement of gas or liquid as heat rises
Heats plant foliage above surface fires and fuels ahead of the flame on steep slopes or if wind driven
Carries firebrands away from fire spotting potential
Can create enormous columns and drive fire behavior
ConvectionConvection Vertical (or other direction) movement of Vertical (or other direction) movement of
gas or liquid as heat risesgas or liquid as heat rises Heats plant foliage above surface fires Heats plant foliage above surface fires
and fuels ahead of the flame on steep and fuels ahead of the flame on steep slopes or if wind drivenslopes or if wind driven
Carries firebrands away from fire Carries firebrands away from fire spotting potentialspotting potential
Can create enormous columns and drive Can create enormous columns and drive fire behaviorfire behavior
Heat Transfer ProcessesHeat Transfer Processes
ConductionConduction Transfer by molecular activity Transfer by molecular activity
withinwithin a solid object a solid object Primary method for raising Primary method for raising
temperatures within large fuelstemperatures within large fuels Occurs between objectsfuels Occurs between objectsfuels
that are in contactthat are in contact Transfers heat in dense fuels Transfers heat in dense fuels
requiring additional heat to reach requiring additional heat to reach ignitionignition
Rate of spread (ROS) rate at which fire front advances through forest fuel (ftsec chainsmin)
Residency Time Duration for flaming combustion to pass a specific location
Flame Length amp Depth
Residency Time = Flame DepthROS
Intensity ndash rate of heat energy during combustion Reaction intensity per unit area (BTUft-2min-1) Fireline Intensity per unit length of the fire front (BTUft-1min-
1)
I = hwr
I fireline intensityh fuel heat contentw weight of fuel consumed per unit arear rate of spread
Flame Length is a good estimate of intensity
Severity Impact of fire on the environment Plants animals soils water
SE
VE
RIT
Y
INTENSITY
LOW
HIGH
HIGHLOW
Backing fire in long unburned longleaf pine
Stand replacing fire in mixed conifer forests
Head fire in frequently burned longleaf pine
Chaparral Brush Fires
1 Weather
2 Fuels 3 Topography
Surface Fuels Grasses Shrubs Litter (leaves)
Woody debris
Ground Fuels Duff (partially
decomposed)
Peat Roots Stumps
mineral soil
litter
fermentation layerhumus
Duff
Aerial Fuels Crown or canopy of
overstory
Ladder Fuels (located between crown and surface fuels)
Smaller trees Vines
Size and Shape Surface areavolume
ratio Grasses Palmetto Branches Logs
10001
401
Particle Density
Fuel Chemistry Volatile oils
Mineral Content Dampening effect on
combustion
Heat Content (stored energy)
6000-12000 BTUlb
Fuel Arrangement Vertical Grasses amp shrubs
Horizontal Litter Downed woody debris
Fuel Loading By size classes
Compactness Bulk density (fuel loadfuelbed volume)
Packing ratio (fuelbed densityparticle density)
Continuity Vertical Horizontal
ALL FUELBED PROPERTIES
Fuel Moisture Content (FMC) Large dampening effect on
combustion Heat sink
FMC changes hourly daily and seasonally
Fuel Moisture Content () = (Water Weight Dry Fuel Weight) x 100
What influences FMC In Dead Fuels Precipitation (amount
and duration) Temperature Relative humidity Wind
Equilibrium Moisture Content For a given temperature and RH dead fuel
will reach a FMC at equilibrium Environmental conditions are not constant Fuel is constantly changes FMC to reach
EMC
The lag time to reach EMC depends on particle size
Timelag categories for dead woody fuels
Timelag Class Fuel Diameter
Timelag Range (hr)
1 Hour 0-14rdquo 0-2
10 Hour frac14rdquo-1rdquo 2-20
100 Hour 1-3rdquo 20-200
1000 Hour 3-8rdquo 200-2000
Timelag or ldquoresponse timerdquo is the time it takes for 63 of the change to occur between one EMC and a second EMC when a fuel in equilibrium with a stable environmental condition is suddenly exposed to a different stable environmental condition
Small diameter fuels react quickly to hourly and daily changes Important to monitor
Large diameter fuels react more to seasonal changes California versus Florida
Fine fuels drive fire behavior
Moisture of Extinction Dead 12-40 Live gt120
Available Fuel
Florida Fine Fuel Moisture Calculation Chart
httpwwwfl-dofcomwildfirerx_traininghtmlcbc
Live Fuels FMC can be much higher than dead
fuels (100-300) Influenced by Drought (KBDI) RH Wind
Ignition of live fuels may largely depend the combustion characteristics of other fuels (eg dead surface fuels)
Duff Moisture Very dry to very moist lt30 FMC duff can burn on its own Potential for tree mortality in
burning long unburned forests May smolder for long durations May cause lots of smoke
FMCWind
Increases O2 Bends flames Increases ROS Dries fuels
convectionwind
radiation
conduction
Slopes Similar effect as
wind Bends flames ROS higher
upslope
Slope Positiontop middle bottom
Aspect
Other topographic features Valleys Box Canyons Steep draws Elevation
ELEVATION
Indicators (on a Rx burn) KBDIgt500 FMC (fine) lt7 RHlt30 Cold front approaching Gusty winds Dust devilsfire whirls Just inland from seabreeze Well-defined convection column Thunderstorms Spotting DI approaching 70
Fire Behavior Prediction Models (eg BehavePlus)
INPUTS OUTPUTSFuel characteristics Rate of
SpreadFMC Fireline IntensitySlope Flame LengthsWind and morehellip
- Slide 9
- Slide 15
- Slide 46
-
Photosynthesis converts radiant energy to stored chemical energy (CO2 + H2O ---light-----gt C6H12O6 + O2)
Combustion reverses photosynthesis(C6H12O6 + O2 ---high temperature-----gt H2O + CO2 + heat and light)
(fuel) (325 C for wood)
Same process as decay and decomposition Begins with endothermic reaction becomes exothermic Produces thermal radiant and kinetic energy
Extinction insufficient heat to sustain combustion
HEAT
WATER ampORGANICGASES
Pre-Ignition
VISIBLE SMOKE
Smoldering
CO CO2
Glowing
2CO WATER
VISIBLE SMOKE
Flaming
4 Phases of Combustion
Pre-ignition Requires heatenergy input to
increase surface temperature gt200˚C
Dehydration Volatilization of waxes oils other
extractives Pyrolysis (chemical decomposition of
organic matter without Oxygenndash inside fuels emits volatiles)
Volatiles either condense into particles (smoke) or are consumed during flaming combustion
HEAT
WATER ampORGANICGASES
Pre-Ignition
Ignition Transition to flaming
combustion gases released by pyrolysis ignite
Surface temperatures around 320 C (600F)
Heat released by combustion brings other fuels to ignition
Flaming combustion Surface temperatures 200- 500˚
C Combustible volatiles ignite
above surface creating flame the GASES are burning not the fuel itself
Combustion occurs in zone above fuel surface
Oxidation produces heat CO2 H2O and incompletely degraded organic compounds
Smoke includes these + other gases which condense or reform above flame zone
2CO WATER
VISIBLE SMOKE
Flaming
Smoldering No visible flames Surface temperatures lt 500 C Carbon buildup on surface reduces gas
production that would maintain flame Occurs when fuels tightly packed Surface char oxidizes to CO2 H2O ash Continued oxidation of other
compounds Smoldering duff and ground fires raise
soil temperature and can kill roots Large quantities of smoke
VISIBLE SMOKE
Smoldering
A result of incomplete combustion Major constituents
Particulate matter Solid or liquid particle suspended in
atmosphere Condensed hydrocarbons and tar
materials Entrained fragments of vegetation and
ash CO2 and CO H2O Gaseous hydrocarbons
Smokevolume burned increases for Low intensity fires in moist or living
fuels High rates of spread (amp less efficient
combustion)
CO CO2
GlowingbullAll volatiles have already been driven off oxygen reaches the combustion surfaces and there is no visible smoke (products are CO2 and CO)bullOxidation of solid fuel accompanied by incandescencebullThis phase follows smoldering combustion continues until temperature drops or only non-combustible ash remains
Radiation For example the sun and your handhellip Electromagnetic waves transfer heat to
fuel surface only
Accounts for most drying and heating of fuel surfaces ahead of flame or on opposite steep slopesndash radiates in all directions
Radiation For example the sun and your handhellipFor example the sun and your handhellip Electromagnetic waves transfer heat to fuel Electromagnetic waves transfer heat to fuel
surface onlysurface only
Accounts for most drying and heating of Accounts for most drying and heating of fuel surfaces ahead of flame or on opposite fuel surfaces ahead of flame or on opposite steep slopesndash radiates in all directionssteep slopesndash radiates in all directions
Convection Vertical (or other direction)
movement of gas or liquid as heat rises
Heats plant foliage above surface fires and fuels ahead of the flame on steep slopes or if wind driven
Carries firebrands away from fire spotting potential
Can create enormous columns and drive fire behavior
ConvectionConvection Vertical (or other direction) movement of Vertical (or other direction) movement of
gas or liquid as heat risesgas or liquid as heat rises Heats plant foliage above surface fires Heats plant foliage above surface fires
and fuels ahead of the flame on steep and fuels ahead of the flame on steep slopes or if wind drivenslopes or if wind driven
Carries firebrands away from fire Carries firebrands away from fire spotting potentialspotting potential
Can create enormous columns and drive Can create enormous columns and drive fire behaviorfire behavior
Heat Transfer ProcessesHeat Transfer Processes
ConductionConduction Transfer by molecular activity Transfer by molecular activity
withinwithin a solid object a solid object Primary method for raising Primary method for raising
temperatures within large fuelstemperatures within large fuels Occurs between objectsfuels Occurs between objectsfuels
that are in contactthat are in contact Transfers heat in dense fuels Transfers heat in dense fuels
requiring additional heat to reach requiring additional heat to reach ignitionignition
Rate of spread (ROS) rate at which fire front advances through forest fuel (ftsec chainsmin)
Residency Time Duration for flaming combustion to pass a specific location
Flame Length amp Depth
Residency Time = Flame DepthROS
Intensity ndash rate of heat energy during combustion Reaction intensity per unit area (BTUft-2min-1) Fireline Intensity per unit length of the fire front (BTUft-1min-
1)
I = hwr
I fireline intensityh fuel heat contentw weight of fuel consumed per unit arear rate of spread
Flame Length is a good estimate of intensity
Severity Impact of fire on the environment Plants animals soils water
SE
VE
RIT
Y
INTENSITY
LOW
HIGH
HIGHLOW
Backing fire in long unburned longleaf pine
Stand replacing fire in mixed conifer forests
Head fire in frequently burned longleaf pine
Chaparral Brush Fires
1 Weather
2 Fuels 3 Topography
Surface Fuels Grasses Shrubs Litter (leaves)
Woody debris
Ground Fuels Duff (partially
decomposed)
Peat Roots Stumps
mineral soil
litter
fermentation layerhumus
Duff
Aerial Fuels Crown or canopy of
overstory
Ladder Fuels (located between crown and surface fuels)
Smaller trees Vines
Size and Shape Surface areavolume
ratio Grasses Palmetto Branches Logs
10001
401
Particle Density
Fuel Chemistry Volatile oils
Mineral Content Dampening effect on
combustion
Heat Content (stored energy)
6000-12000 BTUlb
Fuel Arrangement Vertical Grasses amp shrubs
Horizontal Litter Downed woody debris
Fuel Loading By size classes
Compactness Bulk density (fuel loadfuelbed volume)
Packing ratio (fuelbed densityparticle density)
Continuity Vertical Horizontal
ALL FUELBED PROPERTIES
Fuel Moisture Content (FMC) Large dampening effect on
combustion Heat sink
FMC changes hourly daily and seasonally
Fuel Moisture Content () = (Water Weight Dry Fuel Weight) x 100
What influences FMC In Dead Fuels Precipitation (amount
and duration) Temperature Relative humidity Wind
Equilibrium Moisture Content For a given temperature and RH dead fuel
will reach a FMC at equilibrium Environmental conditions are not constant Fuel is constantly changes FMC to reach
EMC
The lag time to reach EMC depends on particle size
Timelag categories for dead woody fuels
Timelag Class Fuel Diameter
Timelag Range (hr)
1 Hour 0-14rdquo 0-2
10 Hour frac14rdquo-1rdquo 2-20
100 Hour 1-3rdquo 20-200
1000 Hour 3-8rdquo 200-2000
Timelag or ldquoresponse timerdquo is the time it takes for 63 of the change to occur between one EMC and a second EMC when a fuel in equilibrium with a stable environmental condition is suddenly exposed to a different stable environmental condition
Small diameter fuels react quickly to hourly and daily changes Important to monitor
Large diameter fuels react more to seasonal changes California versus Florida
Fine fuels drive fire behavior
Moisture of Extinction Dead 12-40 Live gt120
Available Fuel
Florida Fine Fuel Moisture Calculation Chart
httpwwwfl-dofcomwildfirerx_traininghtmlcbc
Live Fuels FMC can be much higher than dead
fuels (100-300) Influenced by Drought (KBDI) RH Wind
Ignition of live fuels may largely depend the combustion characteristics of other fuels (eg dead surface fuels)
Duff Moisture Very dry to very moist lt30 FMC duff can burn on its own Potential for tree mortality in
burning long unburned forests May smolder for long durations May cause lots of smoke
FMCWind
Increases O2 Bends flames Increases ROS Dries fuels
convectionwind
radiation
conduction
Slopes Similar effect as
wind Bends flames ROS higher
upslope
Slope Positiontop middle bottom
Aspect
Other topographic features Valleys Box Canyons Steep draws Elevation
ELEVATION
Indicators (on a Rx burn) KBDIgt500 FMC (fine) lt7 RHlt30 Cold front approaching Gusty winds Dust devilsfire whirls Just inland from seabreeze Well-defined convection column Thunderstorms Spotting DI approaching 70
Fire Behavior Prediction Models (eg BehavePlus)
INPUTS OUTPUTSFuel characteristics Rate of
SpreadFMC Fireline IntensitySlope Flame LengthsWind and morehellip
- Slide 9
- Slide 15
- Slide 46
-
HEAT
WATER ampORGANICGASES
Pre-Ignition
VISIBLE SMOKE
Smoldering
CO CO2
Glowing
2CO WATER
VISIBLE SMOKE
Flaming
4 Phases of Combustion
Pre-ignition Requires heatenergy input to
increase surface temperature gt200˚C
Dehydration Volatilization of waxes oils other
extractives Pyrolysis (chemical decomposition of
organic matter without Oxygenndash inside fuels emits volatiles)
Volatiles either condense into particles (smoke) or are consumed during flaming combustion
HEAT
WATER ampORGANICGASES
Pre-Ignition
Ignition Transition to flaming
combustion gases released by pyrolysis ignite
Surface temperatures around 320 C (600F)
Heat released by combustion brings other fuels to ignition
Flaming combustion Surface temperatures 200- 500˚
C Combustible volatiles ignite
above surface creating flame the GASES are burning not the fuel itself
Combustion occurs in zone above fuel surface
Oxidation produces heat CO2 H2O and incompletely degraded organic compounds
Smoke includes these + other gases which condense or reform above flame zone
2CO WATER
VISIBLE SMOKE
Flaming
Smoldering No visible flames Surface temperatures lt 500 C Carbon buildup on surface reduces gas
production that would maintain flame Occurs when fuels tightly packed Surface char oxidizes to CO2 H2O ash Continued oxidation of other
compounds Smoldering duff and ground fires raise
soil temperature and can kill roots Large quantities of smoke
VISIBLE SMOKE
Smoldering
A result of incomplete combustion Major constituents
Particulate matter Solid or liquid particle suspended in
atmosphere Condensed hydrocarbons and tar
materials Entrained fragments of vegetation and
ash CO2 and CO H2O Gaseous hydrocarbons
Smokevolume burned increases for Low intensity fires in moist or living
fuels High rates of spread (amp less efficient
combustion)
CO CO2
GlowingbullAll volatiles have already been driven off oxygen reaches the combustion surfaces and there is no visible smoke (products are CO2 and CO)bullOxidation of solid fuel accompanied by incandescencebullThis phase follows smoldering combustion continues until temperature drops or only non-combustible ash remains
Radiation For example the sun and your handhellip Electromagnetic waves transfer heat to
fuel surface only
Accounts for most drying and heating of fuel surfaces ahead of flame or on opposite steep slopesndash radiates in all directions
Radiation For example the sun and your handhellipFor example the sun and your handhellip Electromagnetic waves transfer heat to fuel Electromagnetic waves transfer heat to fuel
surface onlysurface only
Accounts for most drying and heating of Accounts for most drying and heating of fuel surfaces ahead of flame or on opposite fuel surfaces ahead of flame or on opposite steep slopesndash radiates in all directionssteep slopesndash radiates in all directions
Convection Vertical (or other direction)
movement of gas or liquid as heat rises
Heats plant foliage above surface fires and fuels ahead of the flame on steep slopes or if wind driven
Carries firebrands away from fire spotting potential
Can create enormous columns and drive fire behavior
ConvectionConvection Vertical (or other direction) movement of Vertical (or other direction) movement of
gas or liquid as heat risesgas or liquid as heat rises Heats plant foliage above surface fires Heats plant foliage above surface fires
and fuels ahead of the flame on steep and fuels ahead of the flame on steep slopes or if wind drivenslopes or if wind driven
Carries firebrands away from fire Carries firebrands away from fire spotting potentialspotting potential
Can create enormous columns and drive Can create enormous columns and drive fire behaviorfire behavior
Heat Transfer ProcessesHeat Transfer Processes
ConductionConduction Transfer by molecular activity Transfer by molecular activity
withinwithin a solid object a solid object Primary method for raising Primary method for raising
temperatures within large fuelstemperatures within large fuels Occurs between objectsfuels Occurs between objectsfuels
that are in contactthat are in contact Transfers heat in dense fuels Transfers heat in dense fuels
requiring additional heat to reach requiring additional heat to reach ignitionignition
Rate of spread (ROS) rate at which fire front advances through forest fuel (ftsec chainsmin)
Residency Time Duration for flaming combustion to pass a specific location
Flame Length amp Depth
Residency Time = Flame DepthROS
Intensity ndash rate of heat energy during combustion Reaction intensity per unit area (BTUft-2min-1) Fireline Intensity per unit length of the fire front (BTUft-1min-
1)
I = hwr
I fireline intensityh fuel heat contentw weight of fuel consumed per unit arear rate of spread
Flame Length is a good estimate of intensity
Severity Impact of fire on the environment Plants animals soils water
SE
VE
RIT
Y
INTENSITY
LOW
HIGH
HIGHLOW
Backing fire in long unburned longleaf pine
Stand replacing fire in mixed conifer forests
Head fire in frequently burned longleaf pine
Chaparral Brush Fires
1 Weather
2 Fuels 3 Topography
Surface Fuels Grasses Shrubs Litter (leaves)
Woody debris
Ground Fuels Duff (partially
decomposed)
Peat Roots Stumps
mineral soil
litter
fermentation layerhumus
Duff
Aerial Fuels Crown or canopy of
overstory
Ladder Fuels (located between crown and surface fuels)
Smaller trees Vines
Size and Shape Surface areavolume
ratio Grasses Palmetto Branches Logs
10001
401
Particle Density
Fuel Chemistry Volatile oils
Mineral Content Dampening effect on
combustion
Heat Content (stored energy)
6000-12000 BTUlb
Fuel Arrangement Vertical Grasses amp shrubs
Horizontal Litter Downed woody debris
Fuel Loading By size classes
Compactness Bulk density (fuel loadfuelbed volume)
Packing ratio (fuelbed densityparticle density)
Continuity Vertical Horizontal
ALL FUELBED PROPERTIES
Fuel Moisture Content (FMC) Large dampening effect on
combustion Heat sink
FMC changes hourly daily and seasonally
Fuel Moisture Content () = (Water Weight Dry Fuel Weight) x 100
What influences FMC In Dead Fuels Precipitation (amount
and duration) Temperature Relative humidity Wind
Equilibrium Moisture Content For a given temperature and RH dead fuel
will reach a FMC at equilibrium Environmental conditions are not constant Fuel is constantly changes FMC to reach
EMC
The lag time to reach EMC depends on particle size
Timelag categories for dead woody fuels
Timelag Class Fuel Diameter
Timelag Range (hr)
1 Hour 0-14rdquo 0-2
10 Hour frac14rdquo-1rdquo 2-20
100 Hour 1-3rdquo 20-200
1000 Hour 3-8rdquo 200-2000
Timelag or ldquoresponse timerdquo is the time it takes for 63 of the change to occur between one EMC and a second EMC when a fuel in equilibrium with a stable environmental condition is suddenly exposed to a different stable environmental condition
Small diameter fuels react quickly to hourly and daily changes Important to monitor
Large diameter fuels react more to seasonal changes California versus Florida
Fine fuels drive fire behavior
Moisture of Extinction Dead 12-40 Live gt120
Available Fuel
Florida Fine Fuel Moisture Calculation Chart
httpwwwfl-dofcomwildfirerx_traininghtmlcbc
Live Fuels FMC can be much higher than dead
fuels (100-300) Influenced by Drought (KBDI) RH Wind
Ignition of live fuels may largely depend the combustion characteristics of other fuels (eg dead surface fuels)
Duff Moisture Very dry to very moist lt30 FMC duff can burn on its own Potential for tree mortality in
burning long unburned forests May smolder for long durations May cause lots of smoke
FMCWind
Increases O2 Bends flames Increases ROS Dries fuels
convectionwind
radiation
conduction
Slopes Similar effect as
wind Bends flames ROS higher
upslope
Slope Positiontop middle bottom
Aspect
Other topographic features Valleys Box Canyons Steep draws Elevation
ELEVATION
Indicators (on a Rx burn) KBDIgt500 FMC (fine) lt7 RHlt30 Cold front approaching Gusty winds Dust devilsfire whirls Just inland from seabreeze Well-defined convection column Thunderstorms Spotting DI approaching 70
Fire Behavior Prediction Models (eg BehavePlus)
INPUTS OUTPUTSFuel characteristics Rate of
SpreadFMC Fireline IntensitySlope Flame LengthsWind and morehellip
- Slide 9
- Slide 15
- Slide 46
-
Pre-ignition Requires heatenergy input to
increase surface temperature gt200˚C
Dehydration Volatilization of waxes oils other
extractives Pyrolysis (chemical decomposition of
organic matter without Oxygenndash inside fuels emits volatiles)
Volatiles either condense into particles (smoke) or are consumed during flaming combustion
HEAT
WATER ampORGANICGASES
Pre-Ignition
Ignition Transition to flaming
combustion gases released by pyrolysis ignite
Surface temperatures around 320 C (600F)
Heat released by combustion brings other fuels to ignition
Flaming combustion Surface temperatures 200- 500˚
C Combustible volatiles ignite
above surface creating flame the GASES are burning not the fuel itself
Combustion occurs in zone above fuel surface
Oxidation produces heat CO2 H2O and incompletely degraded organic compounds
Smoke includes these + other gases which condense or reform above flame zone
2CO WATER
VISIBLE SMOKE
Flaming
Smoldering No visible flames Surface temperatures lt 500 C Carbon buildup on surface reduces gas
production that would maintain flame Occurs when fuels tightly packed Surface char oxidizes to CO2 H2O ash Continued oxidation of other
compounds Smoldering duff and ground fires raise
soil temperature and can kill roots Large quantities of smoke
VISIBLE SMOKE
Smoldering
A result of incomplete combustion Major constituents
Particulate matter Solid or liquid particle suspended in
atmosphere Condensed hydrocarbons and tar
materials Entrained fragments of vegetation and
ash CO2 and CO H2O Gaseous hydrocarbons
Smokevolume burned increases for Low intensity fires in moist or living
fuels High rates of spread (amp less efficient
combustion)
CO CO2
GlowingbullAll volatiles have already been driven off oxygen reaches the combustion surfaces and there is no visible smoke (products are CO2 and CO)bullOxidation of solid fuel accompanied by incandescencebullThis phase follows smoldering combustion continues until temperature drops or only non-combustible ash remains
Radiation For example the sun and your handhellip Electromagnetic waves transfer heat to
fuel surface only
Accounts for most drying and heating of fuel surfaces ahead of flame or on opposite steep slopesndash radiates in all directions
Radiation For example the sun and your handhellipFor example the sun and your handhellip Electromagnetic waves transfer heat to fuel Electromagnetic waves transfer heat to fuel
surface onlysurface only
Accounts for most drying and heating of Accounts for most drying and heating of fuel surfaces ahead of flame or on opposite fuel surfaces ahead of flame or on opposite steep slopesndash radiates in all directionssteep slopesndash radiates in all directions
Convection Vertical (or other direction)
movement of gas or liquid as heat rises
Heats plant foliage above surface fires and fuels ahead of the flame on steep slopes or if wind driven
Carries firebrands away from fire spotting potential
Can create enormous columns and drive fire behavior
ConvectionConvection Vertical (or other direction) movement of Vertical (or other direction) movement of
gas or liquid as heat risesgas or liquid as heat rises Heats plant foliage above surface fires Heats plant foliage above surface fires
and fuels ahead of the flame on steep and fuels ahead of the flame on steep slopes or if wind drivenslopes or if wind driven
Carries firebrands away from fire Carries firebrands away from fire spotting potentialspotting potential
Can create enormous columns and drive Can create enormous columns and drive fire behaviorfire behavior
Heat Transfer ProcessesHeat Transfer Processes
ConductionConduction Transfer by molecular activity Transfer by molecular activity
withinwithin a solid object a solid object Primary method for raising Primary method for raising
temperatures within large fuelstemperatures within large fuels Occurs between objectsfuels Occurs between objectsfuels
that are in contactthat are in contact Transfers heat in dense fuels Transfers heat in dense fuels
requiring additional heat to reach requiring additional heat to reach ignitionignition
Rate of spread (ROS) rate at which fire front advances through forest fuel (ftsec chainsmin)
Residency Time Duration for flaming combustion to pass a specific location
Flame Length amp Depth
Residency Time = Flame DepthROS
Intensity ndash rate of heat energy during combustion Reaction intensity per unit area (BTUft-2min-1) Fireline Intensity per unit length of the fire front (BTUft-1min-
1)
I = hwr
I fireline intensityh fuel heat contentw weight of fuel consumed per unit arear rate of spread
Flame Length is a good estimate of intensity
Severity Impact of fire on the environment Plants animals soils water
SE
VE
RIT
Y
INTENSITY
LOW
HIGH
HIGHLOW
Backing fire in long unburned longleaf pine
Stand replacing fire in mixed conifer forests
Head fire in frequently burned longleaf pine
Chaparral Brush Fires
1 Weather
2 Fuels 3 Topography
Surface Fuels Grasses Shrubs Litter (leaves)
Woody debris
Ground Fuels Duff (partially
decomposed)
Peat Roots Stumps
mineral soil
litter
fermentation layerhumus
Duff
Aerial Fuels Crown or canopy of
overstory
Ladder Fuels (located between crown and surface fuels)
Smaller trees Vines
Size and Shape Surface areavolume
ratio Grasses Palmetto Branches Logs
10001
401
Particle Density
Fuel Chemistry Volatile oils
Mineral Content Dampening effect on
combustion
Heat Content (stored energy)
6000-12000 BTUlb
Fuel Arrangement Vertical Grasses amp shrubs
Horizontal Litter Downed woody debris
Fuel Loading By size classes
Compactness Bulk density (fuel loadfuelbed volume)
Packing ratio (fuelbed densityparticle density)
Continuity Vertical Horizontal
ALL FUELBED PROPERTIES
Fuel Moisture Content (FMC) Large dampening effect on
combustion Heat sink
FMC changes hourly daily and seasonally
Fuel Moisture Content () = (Water Weight Dry Fuel Weight) x 100
What influences FMC In Dead Fuels Precipitation (amount
and duration) Temperature Relative humidity Wind
Equilibrium Moisture Content For a given temperature and RH dead fuel
will reach a FMC at equilibrium Environmental conditions are not constant Fuel is constantly changes FMC to reach
EMC
The lag time to reach EMC depends on particle size
Timelag categories for dead woody fuels
Timelag Class Fuel Diameter
Timelag Range (hr)
1 Hour 0-14rdquo 0-2
10 Hour frac14rdquo-1rdquo 2-20
100 Hour 1-3rdquo 20-200
1000 Hour 3-8rdquo 200-2000
Timelag or ldquoresponse timerdquo is the time it takes for 63 of the change to occur between one EMC and a second EMC when a fuel in equilibrium with a stable environmental condition is suddenly exposed to a different stable environmental condition
Small diameter fuels react quickly to hourly and daily changes Important to monitor
Large diameter fuels react more to seasonal changes California versus Florida
Fine fuels drive fire behavior
Moisture of Extinction Dead 12-40 Live gt120
Available Fuel
Florida Fine Fuel Moisture Calculation Chart
httpwwwfl-dofcomwildfirerx_traininghtmlcbc
Live Fuels FMC can be much higher than dead
fuels (100-300) Influenced by Drought (KBDI) RH Wind
Ignition of live fuels may largely depend the combustion characteristics of other fuels (eg dead surface fuels)
Duff Moisture Very dry to very moist lt30 FMC duff can burn on its own Potential for tree mortality in
burning long unburned forests May smolder for long durations May cause lots of smoke
FMCWind
Increases O2 Bends flames Increases ROS Dries fuels
convectionwind
radiation
conduction
Slopes Similar effect as
wind Bends flames ROS higher
upslope
Slope Positiontop middle bottom
Aspect
Other topographic features Valleys Box Canyons Steep draws Elevation
ELEVATION
Indicators (on a Rx burn) KBDIgt500 FMC (fine) lt7 RHlt30 Cold front approaching Gusty winds Dust devilsfire whirls Just inland from seabreeze Well-defined convection column Thunderstorms Spotting DI approaching 70
Fire Behavior Prediction Models (eg BehavePlus)
INPUTS OUTPUTSFuel characteristics Rate of
SpreadFMC Fireline IntensitySlope Flame LengthsWind and morehellip
- Slide 9
- Slide 15
- Slide 46
-
Ignition Transition to flaming
combustion gases released by pyrolysis ignite
Surface temperatures around 320 C (600F)
Heat released by combustion brings other fuels to ignition
Flaming combustion Surface temperatures 200- 500˚
C Combustible volatiles ignite
above surface creating flame the GASES are burning not the fuel itself
Combustion occurs in zone above fuel surface
Oxidation produces heat CO2 H2O and incompletely degraded organic compounds
Smoke includes these + other gases which condense or reform above flame zone
2CO WATER
VISIBLE SMOKE
Flaming
Smoldering No visible flames Surface temperatures lt 500 C Carbon buildup on surface reduces gas
production that would maintain flame Occurs when fuels tightly packed Surface char oxidizes to CO2 H2O ash Continued oxidation of other
compounds Smoldering duff and ground fires raise
soil temperature and can kill roots Large quantities of smoke
VISIBLE SMOKE
Smoldering
A result of incomplete combustion Major constituents
Particulate matter Solid or liquid particle suspended in
atmosphere Condensed hydrocarbons and tar
materials Entrained fragments of vegetation and
ash CO2 and CO H2O Gaseous hydrocarbons
Smokevolume burned increases for Low intensity fires in moist or living
fuels High rates of spread (amp less efficient
combustion)
CO CO2
GlowingbullAll volatiles have already been driven off oxygen reaches the combustion surfaces and there is no visible smoke (products are CO2 and CO)bullOxidation of solid fuel accompanied by incandescencebullThis phase follows smoldering combustion continues until temperature drops or only non-combustible ash remains
Radiation For example the sun and your handhellip Electromagnetic waves transfer heat to
fuel surface only
Accounts for most drying and heating of fuel surfaces ahead of flame or on opposite steep slopesndash radiates in all directions
Radiation For example the sun and your handhellipFor example the sun and your handhellip Electromagnetic waves transfer heat to fuel Electromagnetic waves transfer heat to fuel
surface onlysurface only
Accounts for most drying and heating of Accounts for most drying and heating of fuel surfaces ahead of flame or on opposite fuel surfaces ahead of flame or on opposite steep slopesndash radiates in all directionssteep slopesndash radiates in all directions
Convection Vertical (or other direction)
movement of gas or liquid as heat rises
Heats plant foliage above surface fires and fuels ahead of the flame on steep slopes or if wind driven
Carries firebrands away from fire spotting potential
Can create enormous columns and drive fire behavior
ConvectionConvection Vertical (or other direction) movement of Vertical (or other direction) movement of
gas or liquid as heat risesgas or liquid as heat rises Heats plant foliage above surface fires Heats plant foliage above surface fires
and fuels ahead of the flame on steep and fuels ahead of the flame on steep slopes or if wind drivenslopes or if wind driven
Carries firebrands away from fire Carries firebrands away from fire spotting potentialspotting potential
Can create enormous columns and drive Can create enormous columns and drive fire behaviorfire behavior
Heat Transfer ProcessesHeat Transfer Processes
ConductionConduction Transfer by molecular activity Transfer by molecular activity
withinwithin a solid object a solid object Primary method for raising Primary method for raising
temperatures within large fuelstemperatures within large fuels Occurs between objectsfuels Occurs between objectsfuels
that are in contactthat are in contact Transfers heat in dense fuels Transfers heat in dense fuels
requiring additional heat to reach requiring additional heat to reach ignitionignition
Rate of spread (ROS) rate at which fire front advances through forest fuel (ftsec chainsmin)
Residency Time Duration for flaming combustion to pass a specific location
Flame Length amp Depth
Residency Time = Flame DepthROS
Intensity ndash rate of heat energy during combustion Reaction intensity per unit area (BTUft-2min-1) Fireline Intensity per unit length of the fire front (BTUft-1min-
1)
I = hwr
I fireline intensityh fuel heat contentw weight of fuel consumed per unit arear rate of spread
Flame Length is a good estimate of intensity
Severity Impact of fire on the environment Plants animals soils water
SE
VE
RIT
Y
INTENSITY
LOW
HIGH
HIGHLOW
Backing fire in long unburned longleaf pine
Stand replacing fire in mixed conifer forests
Head fire in frequently burned longleaf pine
Chaparral Brush Fires
1 Weather
2 Fuels 3 Topography
Surface Fuels Grasses Shrubs Litter (leaves)
Woody debris
Ground Fuels Duff (partially
decomposed)
Peat Roots Stumps
mineral soil
litter
fermentation layerhumus
Duff
Aerial Fuels Crown or canopy of
overstory
Ladder Fuels (located between crown and surface fuels)
Smaller trees Vines
Size and Shape Surface areavolume
ratio Grasses Palmetto Branches Logs
10001
401
Particle Density
Fuel Chemistry Volatile oils
Mineral Content Dampening effect on
combustion
Heat Content (stored energy)
6000-12000 BTUlb
Fuel Arrangement Vertical Grasses amp shrubs
Horizontal Litter Downed woody debris
Fuel Loading By size classes
Compactness Bulk density (fuel loadfuelbed volume)
Packing ratio (fuelbed densityparticle density)
Continuity Vertical Horizontal
ALL FUELBED PROPERTIES
Fuel Moisture Content (FMC) Large dampening effect on
combustion Heat sink
FMC changes hourly daily and seasonally
Fuel Moisture Content () = (Water Weight Dry Fuel Weight) x 100
What influences FMC In Dead Fuels Precipitation (amount
and duration) Temperature Relative humidity Wind
Equilibrium Moisture Content For a given temperature and RH dead fuel
will reach a FMC at equilibrium Environmental conditions are not constant Fuel is constantly changes FMC to reach
EMC
The lag time to reach EMC depends on particle size
Timelag categories for dead woody fuels
Timelag Class Fuel Diameter
Timelag Range (hr)
1 Hour 0-14rdquo 0-2
10 Hour frac14rdquo-1rdquo 2-20
100 Hour 1-3rdquo 20-200
1000 Hour 3-8rdquo 200-2000
Timelag or ldquoresponse timerdquo is the time it takes for 63 of the change to occur between one EMC and a second EMC when a fuel in equilibrium with a stable environmental condition is suddenly exposed to a different stable environmental condition
Small diameter fuels react quickly to hourly and daily changes Important to monitor
Large diameter fuels react more to seasonal changes California versus Florida
Fine fuels drive fire behavior
Moisture of Extinction Dead 12-40 Live gt120
Available Fuel
Florida Fine Fuel Moisture Calculation Chart
httpwwwfl-dofcomwildfirerx_traininghtmlcbc
Live Fuels FMC can be much higher than dead
fuels (100-300) Influenced by Drought (KBDI) RH Wind
Ignition of live fuels may largely depend the combustion characteristics of other fuels (eg dead surface fuels)
Duff Moisture Very dry to very moist lt30 FMC duff can burn on its own Potential for tree mortality in
burning long unburned forests May smolder for long durations May cause lots of smoke
FMCWind
Increases O2 Bends flames Increases ROS Dries fuels
convectionwind
radiation
conduction
Slopes Similar effect as
wind Bends flames ROS higher
upslope
Slope Positiontop middle bottom
Aspect
Other topographic features Valleys Box Canyons Steep draws Elevation
ELEVATION
Indicators (on a Rx burn) KBDIgt500 FMC (fine) lt7 RHlt30 Cold front approaching Gusty winds Dust devilsfire whirls Just inland from seabreeze Well-defined convection column Thunderstorms Spotting DI approaching 70
Fire Behavior Prediction Models (eg BehavePlus)
INPUTS OUTPUTSFuel characteristics Rate of
SpreadFMC Fireline IntensitySlope Flame LengthsWind and morehellip
- Slide 9
- Slide 15
- Slide 46
-
Flaming combustion Surface temperatures 200- 500˚
C Combustible volatiles ignite
above surface creating flame the GASES are burning not the fuel itself
Combustion occurs in zone above fuel surface
Oxidation produces heat CO2 H2O and incompletely degraded organic compounds
Smoke includes these + other gases which condense or reform above flame zone
2CO WATER
VISIBLE SMOKE
Flaming
Smoldering No visible flames Surface temperatures lt 500 C Carbon buildup on surface reduces gas
production that would maintain flame Occurs when fuels tightly packed Surface char oxidizes to CO2 H2O ash Continued oxidation of other
compounds Smoldering duff and ground fires raise
soil temperature and can kill roots Large quantities of smoke
VISIBLE SMOKE
Smoldering
A result of incomplete combustion Major constituents
Particulate matter Solid or liquid particle suspended in
atmosphere Condensed hydrocarbons and tar
materials Entrained fragments of vegetation and
ash CO2 and CO H2O Gaseous hydrocarbons
Smokevolume burned increases for Low intensity fires in moist or living
fuels High rates of spread (amp less efficient
combustion)
CO CO2
GlowingbullAll volatiles have already been driven off oxygen reaches the combustion surfaces and there is no visible smoke (products are CO2 and CO)bullOxidation of solid fuel accompanied by incandescencebullThis phase follows smoldering combustion continues until temperature drops or only non-combustible ash remains
Radiation For example the sun and your handhellip Electromagnetic waves transfer heat to
fuel surface only
Accounts for most drying and heating of fuel surfaces ahead of flame or on opposite steep slopesndash radiates in all directions
Radiation For example the sun and your handhellipFor example the sun and your handhellip Electromagnetic waves transfer heat to fuel Electromagnetic waves transfer heat to fuel
surface onlysurface only
Accounts for most drying and heating of Accounts for most drying and heating of fuel surfaces ahead of flame or on opposite fuel surfaces ahead of flame or on opposite steep slopesndash radiates in all directionssteep slopesndash radiates in all directions
Convection Vertical (or other direction)
movement of gas or liquid as heat rises
Heats plant foliage above surface fires and fuels ahead of the flame on steep slopes or if wind driven
Carries firebrands away from fire spotting potential
Can create enormous columns and drive fire behavior
ConvectionConvection Vertical (or other direction) movement of Vertical (or other direction) movement of
gas or liquid as heat risesgas or liquid as heat rises Heats plant foliage above surface fires Heats plant foliage above surface fires
and fuels ahead of the flame on steep and fuels ahead of the flame on steep slopes or if wind drivenslopes or if wind driven
Carries firebrands away from fire Carries firebrands away from fire spotting potentialspotting potential
Can create enormous columns and drive Can create enormous columns and drive fire behaviorfire behavior
Heat Transfer ProcessesHeat Transfer Processes
ConductionConduction Transfer by molecular activity Transfer by molecular activity
withinwithin a solid object a solid object Primary method for raising Primary method for raising
temperatures within large fuelstemperatures within large fuels Occurs between objectsfuels Occurs between objectsfuels
that are in contactthat are in contact Transfers heat in dense fuels Transfers heat in dense fuels
requiring additional heat to reach requiring additional heat to reach ignitionignition
Rate of spread (ROS) rate at which fire front advances through forest fuel (ftsec chainsmin)
Residency Time Duration for flaming combustion to pass a specific location
Flame Length amp Depth
Residency Time = Flame DepthROS
Intensity ndash rate of heat energy during combustion Reaction intensity per unit area (BTUft-2min-1) Fireline Intensity per unit length of the fire front (BTUft-1min-
1)
I = hwr
I fireline intensityh fuel heat contentw weight of fuel consumed per unit arear rate of spread
Flame Length is a good estimate of intensity
Severity Impact of fire on the environment Plants animals soils water
SE
VE
RIT
Y
INTENSITY
LOW
HIGH
HIGHLOW
Backing fire in long unburned longleaf pine
Stand replacing fire in mixed conifer forests
Head fire in frequently burned longleaf pine
Chaparral Brush Fires
1 Weather
2 Fuels 3 Topography
Surface Fuels Grasses Shrubs Litter (leaves)
Woody debris
Ground Fuels Duff (partially
decomposed)
Peat Roots Stumps
mineral soil
litter
fermentation layerhumus
Duff
Aerial Fuels Crown or canopy of
overstory
Ladder Fuels (located between crown and surface fuels)
Smaller trees Vines
Size and Shape Surface areavolume
ratio Grasses Palmetto Branches Logs
10001
401
Particle Density
Fuel Chemistry Volatile oils
Mineral Content Dampening effect on
combustion
Heat Content (stored energy)
6000-12000 BTUlb
Fuel Arrangement Vertical Grasses amp shrubs
Horizontal Litter Downed woody debris
Fuel Loading By size classes
Compactness Bulk density (fuel loadfuelbed volume)
Packing ratio (fuelbed densityparticle density)
Continuity Vertical Horizontal
ALL FUELBED PROPERTIES
Fuel Moisture Content (FMC) Large dampening effect on
combustion Heat sink
FMC changes hourly daily and seasonally
Fuel Moisture Content () = (Water Weight Dry Fuel Weight) x 100
What influences FMC In Dead Fuels Precipitation (amount
and duration) Temperature Relative humidity Wind
Equilibrium Moisture Content For a given temperature and RH dead fuel
will reach a FMC at equilibrium Environmental conditions are not constant Fuel is constantly changes FMC to reach
EMC
The lag time to reach EMC depends on particle size
Timelag categories for dead woody fuels
Timelag Class Fuel Diameter
Timelag Range (hr)
1 Hour 0-14rdquo 0-2
10 Hour frac14rdquo-1rdquo 2-20
100 Hour 1-3rdquo 20-200
1000 Hour 3-8rdquo 200-2000
Timelag or ldquoresponse timerdquo is the time it takes for 63 of the change to occur between one EMC and a second EMC when a fuel in equilibrium with a stable environmental condition is suddenly exposed to a different stable environmental condition
Small diameter fuels react quickly to hourly and daily changes Important to monitor
Large diameter fuels react more to seasonal changes California versus Florida
Fine fuels drive fire behavior
Moisture of Extinction Dead 12-40 Live gt120
Available Fuel
Florida Fine Fuel Moisture Calculation Chart
httpwwwfl-dofcomwildfirerx_traininghtmlcbc
Live Fuels FMC can be much higher than dead
fuels (100-300) Influenced by Drought (KBDI) RH Wind
Ignition of live fuels may largely depend the combustion characteristics of other fuels (eg dead surface fuels)
Duff Moisture Very dry to very moist lt30 FMC duff can burn on its own Potential for tree mortality in
burning long unburned forests May smolder for long durations May cause lots of smoke
FMCWind
Increases O2 Bends flames Increases ROS Dries fuels
convectionwind
radiation
conduction
Slopes Similar effect as
wind Bends flames ROS higher
upslope
Slope Positiontop middle bottom
Aspect
Other topographic features Valleys Box Canyons Steep draws Elevation
ELEVATION
Indicators (on a Rx burn) KBDIgt500 FMC (fine) lt7 RHlt30 Cold front approaching Gusty winds Dust devilsfire whirls Just inland from seabreeze Well-defined convection column Thunderstorms Spotting DI approaching 70
Fire Behavior Prediction Models (eg BehavePlus)
INPUTS OUTPUTSFuel characteristics Rate of
SpreadFMC Fireline IntensitySlope Flame LengthsWind and morehellip
- Slide 9
- Slide 15
- Slide 46
-
Smoldering No visible flames Surface temperatures lt 500 C Carbon buildup on surface reduces gas
production that would maintain flame Occurs when fuels tightly packed Surface char oxidizes to CO2 H2O ash Continued oxidation of other
compounds Smoldering duff and ground fires raise
soil temperature and can kill roots Large quantities of smoke
VISIBLE SMOKE
Smoldering
A result of incomplete combustion Major constituents
Particulate matter Solid or liquid particle suspended in
atmosphere Condensed hydrocarbons and tar
materials Entrained fragments of vegetation and
ash CO2 and CO H2O Gaseous hydrocarbons
Smokevolume burned increases for Low intensity fires in moist or living
fuels High rates of spread (amp less efficient
combustion)
CO CO2
GlowingbullAll volatiles have already been driven off oxygen reaches the combustion surfaces and there is no visible smoke (products are CO2 and CO)bullOxidation of solid fuel accompanied by incandescencebullThis phase follows smoldering combustion continues until temperature drops or only non-combustible ash remains
Radiation For example the sun and your handhellip Electromagnetic waves transfer heat to
fuel surface only
Accounts for most drying and heating of fuel surfaces ahead of flame or on opposite steep slopesndash radiates in all directions
Radiation For example the sun and your handhellipFor example the sun and your handhellip Electromagnetic waves transfer heat to fuel Electromagnetic waves transfer heat to fuel
surface onlysurface only
Accounts for most drying and heating of Accounts for most drying and heating of fuel surfaces ahead of flame or on opposite fuel surfaces ahead of flame or on opposite steep slopesndash radiates in all directionssteep slopesndash radiates in all directions
Convection Vertical (or other direction)
movement of gas or liquid as heat rises
Heats plant foliage above surface fires and fuels ahead of the flame on steep slopes or if wind driven
Carries firebrands away from fire spotting potential
Can create enormous columns and drive fire behavior
ConvectionConvection Vertical (or other direction) movement of Vertical (or other direction) movement of
gas or liquid as heat risesgas or liquid as heat rises Heats plant foliage above surface fires Heats plant foliage above surface fires
and fuels ahead of the flame on steep and fuels ahead of the flame on steep slopes or if wind drivenslopes or if wind driven
Carries firebrands away from fire Carries firebrands away from fire spotting potentialspotting potential
Can create enormous columns and drive Can create enormous columns and drive fire behaviorfire behavior
Heat Transfer ProcessesHeat Transfer Processes
ConductionConduction Transfer by molecular activity Transfer by molecular activity
withinwithin a solid object a solid object Primary method for raising Primary method for raising
temperatures within large fuelstemperatures within large fuels Occurs between objectsfuels Occurs between objectsfuels
that are in contactthat are in contact Transfers heat in dense fuels Transfers heat in dense fuels
requiring additional heat to reach requiring additional heat to reach ignitionignition
Rate of spread (ROS) rate at which fire front advances through forest fuel (ftsec chainsmin)
Residency Time Duration for flaming combustion to pass a specific location
Flame Length amp Depth
Residency Time = Flame DepthROS
Intensity ndash rate of heat energy during combustion Reaction intensity per unit area (BTUft-2min-1) Fireline Intensity per unit length of the fire front (BTUft-1min-
1)
I = hwr
I fireline intensityh fuel heat contentw weight of fuel consumed per unit arear rate of spread
Flame Length is a good estimate of intensity
Severity Impact of fire on the environment Plants animals soils water
SE
VE
RIT
Y
INTENSITY
LOW
HIGH
HIGHLOW
Backing fire in long unburned longleaf pine
Stand replacing fire in mixed conifer forests
Head fire in frequently burned longleaf pine
Chaparral Brush Fires
1 Weather
2 Fuels 3 Topography
Surface Fuels Grasses Shrubs Litter (leaves)
Woody debris
Ground Fuels Duff (partially
decomposed)
Peat Roots Stumps
mineral soil
litter
fermentation layerhumus
Duff
Aerial Fuels Crown or canopy of
overstory
Ladder Fuels (located between crown and surface fuels)
Smaller trees Vines
Size and Shape Surface areavolume
ratio Grasses Palmetto Branches Logs
10001
401
Particle Density
Fuel Chemistry Volatile oils
Mineral Content Dampening effect on
combustion
Heat Content (stored energy)
6000-12000 BTUlb
Fuel Arrangement Vertical Grasses amp shrubs
Horizontal Litter Downed woody debris
Fuel Loading By size classes
Compactness Bulk density (fuel loadfuelbed volume)
Packing ratio (fuelbed densityparticle density)
Continuity Vertical Horizontal
ALL FUELBED PROPERTIES
Fuel Moisture Content (FMC) Large dampening effect on
combustion Heat sink
FMC changes hourly daily and seasonally
Fuel Moisture Content () = (Water Weight Dry Fuel Weight) x 100
What influences FMC In Dead Fuels Precipitation (amount
and duration) Temperature Relative humidity Wind
Equilibrium Moisture Content For a given temperature and RH dead fuel
will reach a FMC at equilibrium Environmental conditions are not constant Fuel is constantly changes FMC to reach
EMC
The lag time to reach EMC depends on particle size
Timelag categories for dead woody fuels
Timelag Class Fuel Diameter
Timelag Range (hr)
1 Hour 0-14rdquo 0-2
10 Hour frac14rdquo-1rdquo 2-20
100 Hour 1-3rdquo 20-200
1000 Hour 3-8rdquo 200-2000
Timelag or ldquoresponse timerdquo is the time it takes for 63 of the change to occur between one EMC and a second EMC when a fuel in equilibrium with a stable environmental condition is suddenly exposed to a different stable environmental condition
Small diameter fuels react quickly to hourly and daily changes Important to monitor
Large diameter fuels react more to seasonal changes California versus Florida
Fine fuels drive fire behavior
Moisture of Extinction Dead 12-40 Live gt120
Available Fuel
Florida Fine Fuel Moisture Calculation Chart
httpwwwfl-dofcomwildfirerx_traininghtmlcbc
Live Fuels FMC can be much higher than dead
fuels (100-300) Influenced by Drought (KBDI) RH Wind
Ignition of live fuels may largely depend the combustion characteristics of other fuels (eg dead surface fuels)
Duff Moisture Very dry to very moist lt30 FMC duff can burn on its own Potential for tree mortality in
burning long unburned forests May smolder for long durations May cause lots of smoke
FMCWind
Increases O2 Bends flames Increases ROS Dries fuels
convectionwind
radiation
conduction
Slopes Similar effect as
wind Bends flames ROS higher
upslope
Slope Positiontop middle bottom
Aspect
Other topographic features Valleys Box Canyons Steep draws Elevation
ELEVATION
Indicators (on a Rx burn) KBDIgt500 FMC (fine) lt7 RHlt30 Cold front approaching Gusty winds Dust devilsfire whirls Just inland from seabreeze Well-defined convection column Thunderstorms Spotting DI approaching 70
Fire Behavior Prediction Models (eg BehavePlus)
INPUTS OUTPUTSFuel characteristics Rate of
SpreadFMC Fireline IntensitySlope Flame LengthsWind and morehellip
- Slide 9
- Slide 15
- Slide 46
-
A result of incomplete combustion Major constituents
Particulate matter Solid or liquid particle suspended in
atmosphere Condensed hydrocarbons and tar
materials Entrained fragments of vegetation and
ash CO2 and CO H2O Gaseous hydrocarbons
Smokevolume burned increases for Low intensity fires in moist or living
fuels High rates of spread (amp less efficient
combustion)
CO CO2
GlowingbullAll volatiles have already been driven off oxygen reaches the combustion surfaces and there is no visible smoke (products are CO2 and CO)bullOxidation of solid fuel accompanied by incandescencebullThis phase follows smoldering combustion continues until temperature drops or only non-combustible ash remains
Radiation For example the sun and your handhellip Electromagnetic waves transfer heat to
fuel surface only
Accounts for most drying and heating of fuel surfaces ahead of flame or on opposite steep slopesndash radiates in all directions
Radiation For example the sun and your handhellipFor example the sun and your handhellip Electromagnetic waves transfer heat to fuel Electromagnetic waves transfer heat to fuel
surface onlysurface only
Accounts for most drying and heating of Accounts for most drying and heating of fuel surfaces ahead of flame or on opposite fuel surfaces ahead of flame or on opposite steep slopesndash radiates in all directionssteep slopesndash radiates in all directions
Convection Vertical (or other direction)
movement of gas or liquid as heat rises
Heats plant foliage above surface fires and fuels ahead of the flame on steep slopes or if wind driven
Carries firebrands away from fire spotting potential
Can create enormous columns and drive fire behavior
ConvectionConvection Vertical (or other direction) movement of Vertical (or other direction) movement of
gas or liquid as heat risesgas or liquid as heat rises Heats plant foliage above surface fires Heats plant foliage above surface fires
and fuels ahead of the flame on steep and fuels ahead of the flame on steep slopes or if wind drivenslopes or if wind driven
Carries firebrands away from fire Carries firebrands away from fire spotting potentialspotting potential
Can create enormous columns and drive Can create enormous columns and drive fire behaviorfire behavior
Heat Transfer ProcessesHeat Transfer Processes
ConductionConduction Transfer by molecular activity Transfer by molecular activity
withinwithin a solid object a solid object Primary method for raising Primary method for raising
temperatures within large fuelstemperatures within large fuels Occurs between objectsfuels Occurs between objectsfuels
that are in contactthat are in contact Transfers heat in dense fuels Transfers heat in dense fuels
requiring additional heat to reach requiring additional heat to reach ignitionignition
Rate of spread (ROS) rate at which fire front advances through forest fuel (ftsec chainsmin)
Residency Time Duration for flaming combustion to pass a specific location
Flame Length amp Depth
Residency Time = Flame DepthROS
Intensity ndash rate of heat energy during combustion Reaction intensity per unit area (BTUft-2min-1) Fireline Intensity per unit length of the fire front (BTUft-1min-
1)
I = hwr
I fireline intensityh fuel heat contentw weight of fuel consumed per unit arear rate of spread
Flame Length is a good estimate of intensity
Severity Impact of fire on the environment Plants animals soils water
SE
VE
RIT
Y
INTENSITY
LOW
HIGH
HIGHLOW
Backing fire in long unburned longleaf pine
Stand replacing fire in mixed conifer forests
Head fire in frequently burned longleaf pine
Chaparral Brush Fires
1 Weather
2 Fuels 3 Topography
Surface Fuels Grasses Shrubs Litter (leaves)
Woody debris
Ground Fuels Duff (partially
decomposed)
Peat Roots Stumps
mineral soil
litter
fermentation layerhumus
Duff
Aerial Fuels Crown or canopy of
overstory
Ladder Fuels (located between crown and surface fuels)
Smaller trees Vines
Size and Shape Surface areavolume
ratio Grasses Palmetto Branches Logs
10001
401
Particle Density
Fuel Chemistry Volatile oils
Mineral Content Dampening effect on
combustion
Heat Content (stored energy)
6000-12000 BTUlb
Fuel Arrangement Vertical Grasses amp shrubs
Horizontal Litter Downed woody debris
Fuel Loading By size classes
Compactness Bulk density (fuel loadfuelbed volume)
Packing ratio (fuelbed densityparticle density)
Continuity Vertical Horizontal
ALL FUELBED PROPERTIES
Fuel Moisture Content (FMC) Large dampening effect on
combustion Heat sink
FMC changes hourly daily and seasonally
Fuel Moisture Content () = (Water Weight Dry Fuel Weight) x 100
What influences FMC In Dead Fuels Precipitation (amount
and duration) Temperature Relative humidity Wind
Equilibrium Moisture Content For a given temperature and RH dead fuel
will reach a FMC at equilibrium Environmental conditions are not constant Fuel is constantly changes FMC to reach
EMC
The lag time to reach EMC depends on particle size
Timelag categories for dead woody fuels
Timelag Class Fuel Diameter
Timelag Range (hr)
1 Hour 0-14rdquo 0-2
10 Hour frac14rdquo-1rdquo 2-20
100 Hour 1-3rdquo 20-200
1000 Hour 3-8rdquo 200-2000
Timelag or ldquoresponse timerdquo is the time it takes for 63 of the change to occur between one EMC and a second EMC when a fuel in equilibrium with a stable environmental condition is suddenly exposed to a different stable environmental condition
Small diameter fuels react quickly to hourly and daily changes Important to monitor
Large diameter fuels react more to seasonal changes California versus Florida
Fine fuels drive fire behavior
Moisture of Extinction Dead 12-40 Live gt120
Available Fuel
Florida Fine Fuel Moisture Calculation Chart
httpwwwfl-dofcomwildfirerx_traininghtmlcbc
Live Fuels FMC can be much higher than dead
fuels (100-300) Influenced by Drought (KBDI) RH Wind
Ignition of live fuels may largely depend the combustion characteristics of other fuels (eg dead surface fuels)
Duff Moisture Very dry to very moist lt30 FMC duff can burn on its own Potential for tree mortality in
burning long unburned forests May smolder for long durations May cause lots of smoke
FMCWind
Increases O2 Bends flames Increases ROS Dries fuels
convectionwind
radiation
conduction
Slopes Similar effect as
wind Bends flames ROS higher
upslope
Slope Positiontop middle bottom
Aspect
Other topographic features Valleys Box Canyons Steep draws Elevation
ELEVATION
Indicators (on a Rx burn) KBDIgt500 FMC (fine) lt7 RHlt30 Cold front approaching Gusty winds Dust devilsfire whirls Just inland from seabreeze Well-defined convection column Thunderstorms Spotting DI approaching 70
Fire Behavior Prediction Models (eg BehavePlus)
INPUTS OUTPUTSFuel characteristics Rate of
SpreadFMC Fireline IntensitySlope Flame LengthsWind and morehellip
- Slide 9
- Slide 15
- Slide 46
-
CO CO2
GlowingbullAll volatiles have already been driven off oxygen reaches the combustion surfaces and there is no visible smoke (products are CO2 and CO)bullOxidation of solid fuel accompanied by incandescencebullThis phase follows smoldering combustion continues until temperature drops or only non-combustible ash remains
Radiation For example the sun and your handhellip Electromagnetic waves transfer heat to
fuel surface only
Accounts for most drying and heating of fuel surfaces ahead of flame or on opposite steep slopesndash radiates in all directions
Radiation For example the sun and your handhellipFor example the sun and your handhellip Electromagnetic waves transfer heat to fuel Electromagnetic waves transfer heat to fuel
surface onlysurface only
Accounts for most drying and heating of Accounts for most drying and heating of fuel surfaces ahead of flame or on opposite fuel surfaces ahead of flame or on opposite steep slopesndash radiates in all directionssteep slopesndash radiates in all directions
Convection Vertical (or other direction)
movement of gas or liquid as heat rises
Heats plant foliage above surface fires and fuels ahead of the flame on steep slopes or if wind driven
Carries firebrands away from fire spotting potential
Can create enormous columns and drive fire behavior
ConvectionConvection Vertical (or other direction) movement of Vertical (or other direction) movement of
gas or liquid as heat risesgas or liquid as heat rises Heats plant foliage above surface fires Heats plant foliage above surface fires
and fuels ahead of the flame on steep and fuels ahead of the flame on steep slopes or if wind drivenslopes or if wind driven
Carries firebrands away from fire Carries firebrands away from fire spotting potentialspotting potential
Can create enormous columns and drive Can create enormous columns and drive fire behaviorfire behavior
Heat Transfer ProcessesHeat Transfer Processes
ConductionConduction Transfer by molecular activity Transfer by molecular activity
withinwithin a solid object a solid object Primary method for raising Primary method for raising
temperatures within large fuelstemperatures within large fuels Occurs between objectsfuels Occurs between objectsfuels
that are in contactthat are in contact Transfers heat in dense fuels Transfers heat in dense fuels
requiring additional heat to reach requiring additional heat to reach ignitionignition
Rate of spread (ROS) rate at which fire front advances through forest fuel (ftsec chainsmin)
Residency Time Duration for flaming combustion to pass a specific location
Flame Length amp Depth
Residency Time = Flame DepthROS
Intensity ndash rate of heat energy during combustion Reaction intensity per unit area (BTUft-2min-1) Fireline Intensity per unit length of the fire front (BTUft-1min-
1)
I = hwr
I fireline intensityh fuel heat contentw weight of fuel consumed per unit arear rate of spread
Flame Length is a good estimate of intensity
Severity Impact of fire on the environment Plants animals soils water
SE
VE
RIT
Y
INTENSITY
LOW
HIGH
HIGHLOW
Backing fire in long unburned longleaf pine
Stand replacing fire in mixed conifer forests
Head fire in frequently burned longleaf pine
Chaparral Brush Fires
1 Weather
2 Fuels 3 Topography
Surface Fuels Grasses Shrubs Litter (leaves)
Woody debris
Ground Fuels Duff (partially
decomposed)
Peat Roots Stumps
mineral soil
litter
fermentation layerhumus
Duff
Aerial Fuels Crown or canopy of
overstory
Ladder Fuels (located between crown and surface fuels)
Smaller trees Vines
Size and Shape Surface areavolume
ratio Grasses Palmetto Branches Logs
10001
401
Particle Density
Fuel Chemistry Volatile oils
Mineral Content Dampening effect on
combustion
Heat Content (stored energy)
6000-12000 BTUlb
Fuel Arrangement Vertical Grasses amp shrubs
Horizontal Litter Downed woody debris
Fuel Loading By size classes
Compactness Bulk density (fuel loadfuelbed volume)
Packing ratio (fuelbed densityparticle density)
Continuity Vertical Horizontal
ALL FUELBED PROPERTIES
Fuel Moisture Content (FMC) Large dampening effect on
combustion Heat sink
FMC changes hourly daily and seasonally
Fuel Moisture Content () = (Water Weight Dry Fuel Weight) x 100
What influences FMC In Dead Fuels Precipitation (amount
and duration) Temperature Relative humidity Wind
Equilibrium Moisture Content For a given temperature and RH dead fuel
will reach a FMC at equilibrium Environmental conditions are not constant Fuel is constantly changes FMC to reach
EMC
The lag time to reach EMC depends on particle size
Timelag categories for dead woody fuels
Timelag Class Fuel Diameter
Timelag Range (hr)
1 Hour 0-14rdquo 0-2
10 Hour frac14rdquo-1rdquo 2-20
100 Hour 1-3rdquo 20-200
1000 Hour 3-8rdquo 200-2000
Timelag or ldquoresponse timerdquo is the time it takes for 63 of the change to occur between one EMC and a second EMC when a fuel in equilibrium with a stable environmental condition is suddenly exposed to a different stable environmental condition
Small diameter fuels react quickly to hourly and daily changes Important to monitor
Large diameter fuels react more to seasonal changes California versus Florida
Fine fuels drive fire behavior
Moisture of Extinction Dead 12-40 Live gt120
Available Fuel
Florida Fine Fuel Moisture Calculation Chart
httpwwwfl-dofcomwildfirerx_traininghtmlcbc
Live Fuels FMC can be much higher than dead
fuels (100-300) Influenced by Drought (KBDI) RH Wind
Ignition of live fuels may largely depend the combustion characteristics of other fuels (eg dead surface fuels)
Duff Moisture Very dry to very moist lt30 FMC duff can burn on its own Potential for tree mortality in
burning long unburned forests May smolder for long durations May cause lots of smoke
FMCWind
Increases O2 Bends flames Increases ROS Dries fuels
convectionwind
radiation
conduction
Slopes Similar effect as
wind Bends flames ROS higher
upslope
Slope Positiontop middle bottom
Aspect
Other topographic features Valleys Box Canyons Steep draws Elevation
ELEVATION
Indicators (on a Rx burn) KBDIgt500 FMC (fine) lt7 RHlt30 Cold front approaching Gusty winds Dust devilsfire whirls Just inland from seabreeze Well-defined convection column Thunderstorms Spotting DI approaching 70
Fire Behavior Prediction Models (eg BehavePlus)
INPUTS OUTPUTSFuel characteristics Rate of
SpreadFMC Fireline IntensitySlope Flame LengthsWind and morehellip
- Slide 9
- Slide 15
- Slide 46
-
Radiation For example the sun and your handhellip Electromagnetic waves transfer heat to
fuel surface only
Accounts for most drying and heating of fuel surfaces ahead of flame or on opposite steep slopesndash radiates in all directions
Radiation For example the sun and your handhellipFor example the sun and your handhellip Electromagnetic waves transfer heat to fuel Electromagnetic waves transfer heat to fuel
surface onlysurface only
Accounts for most drying and heating of Accounts for most drying and heating of fuel surfaces ahead of flame or on opposite fuel surfaces ahead of flame or on opposite steep slopesndash radiates in all directionssteep slopesndash radiates in all directions
Convection Vertical (or other direction)
movement of gas or liquid as heat rises
Heats plant foliage above surface fires and fuels ahead of the flame on steep slopes or if wind driven
Carries firebrands away from fire spotting potential
Can create enormous columns and drive fire behavior
ConvectionConvection Vertical (or other direction) movement of Vertical (or other direction) movement of
gas or liquid as heat risesgas or liquid as heat rises Heats plant foliage above surface fires Heats plant foliage above surface fires
and fuels ahead of the flame on steep and fuels ahead of the flame on steep slopes or if wind drivenslopes or if wind driven
Carries firebrands away from fire Carries firebrands away from fire spotting potentialspotting potential
Can create enormous columns and drive Can create enormous columns and drive fire behaviorfire behavior
Heat Transfer ProcessesHeat Transfer Processes
ConductionConduction Transfer by molecular activity Transfer by molecular activity
withinwithin a solid object a solid object Primary method for raising Primary method for raising
temperatures within large fuelstemperatures within large fuels Occurs between objectsfuels Occurs between objectsfuels
that are in contactthat are in contact Transfers heat in dense fuels Transfers heat in dense fuels
requiring additional heat to reach requiring additional heat to reach ignitionignition
Rate of spread (ROS) rate at which fire front advances through forest fuel (ftsec chainsmin)
Residency Time Duration for flaming combustion to pass a specific location
Flame Length amp Depth
Residency Time = Flame DepthROS
Intensity ndash rate of heat energy during combustion Reaction intensity per unit area (BTUft-2min-1) Fireline Intensity per unit length of the fire front (BTUft-1min-
1)
I = hwr
I fireline intensityh fuel heat contentw weight of fuel consumed per unit arear rate of spread
Flame Length is a good estimate of intensity
Severity Impact of fire on the environment Plants animals soils water
SE
VE
RIT
Y
INTENSITY
LOW
HIGH
HIGHLOW
Backing fire in long unburned longleaf pine
Stand replacing fire in mixed conifer forests
Head fire in frequently burned longleaf pine
Chaparral Brush Fires
1 Weather
2 Fuels 3 Topography
Surface Fuels Grasses Shrubs Litter (leaves)
Woody debris
Ground Fuels Duff (partially
decomposed)
Peat Roots Stumps
mineral soil
litter
fermentation layerhumus
Duff
Aerial Fuels Crown or canopy of
overstory
Ladder Fuels (located between crown and surface fuels)
Smaller trees Vines
Size and Shape Surface areavolume
ratio Grasses Palmetto Branches Logs
10001
401
Particle Density
Fuel Chemistry Volatile oils
Mineral Content Dampening effect on
combustion
Heat Content (stored energy)
6000-12000 BTUlb
Fuel Arrangement Vertical Grasses amp shrubs
Horizontal Litter Downed woody debris
Fuel Loading By size classes
Compactness Bulk density (fuel loadfuelbed volume)
Packing ratio (fuelbed densityparticle density)
Continuity Vertical Horizontal
ALL FUELBED PROPERTIES
Fuel Moisture Content (FMC) Large dampening effect on
combustion Heat sink
FMC changes hourly daily and seasonally
Fuel Moisture Content () = (Water Weight Dry Fuel Weight) x 100
What influences FMC In Dead Fuels Precipitation (amount
and duration) Temperature Relative humidity Wind
Equilibrium Moisture Content For a given temperature and RH dead fuel
will reach a FMC at equilibrium Environmental conditions are not constant Fuel is constantly changes FMC to reach
EMC
The lag time to reach EMC depends on particle size
Timelag categories for dead woody fuels
Timelag Class Fuel Diameter
Timelag Range (hr)
1 Hour 0-14rdquo 0-2
10 Hour frac14rdquo-1rdquo 2-20
100 Hour 1-3rdquo 20-200
1000 Hour 3-8rdquo 200-2000
Timelag or ldquoresponse timerdquo is the time it takes for 63 of the change to occur between one EMC and a second EMC when a fuel in equilibrium with a stable environmental condition is suddenly exposed to a different stable environmental condition
Small diameter fuels react quickly to hourly and daily changes Important to monitor
Large diameter fuels react more to seasonal changes California versus Florida
Fine fuels drive fire behavior
Moisture of Extinction Dead 12-40 Live gt120
Available Fuel
Florida Fine Fuel Moisture Calculation Chart
httpwwwfl-dofcomwildfirerx_traininghtmlcbc
Live Fuels FMC can be much higher than dead
fuels (100-300) Influenced by Drought (KBDI) RH Wind
Ignition of live fuels may largely depend the combustion characteristics of other fuels (eg dead surface fuels)
Duff Moisture Very dry to very moist lt30 FMC duff can burn on its own Potential for tree mortality in
burning long unburned forests May smolder for long durations May cause lots of smoke
FMCWind
Increases O2 Bends flames Increases ROS Dries fuels
convectionwind
radiation
conduction
Slopes Similar effect as
wind Bends flames ROS higher
upslope
Slope Positiontop middle bottom
Aspect
Other topographic features Valleys Box Canyons Steep draws Elevation
ELEVATION
Indicators (on a Rx burn) KBDIgt500 FMC (fine) lt7 RHlt30 Cold front approaching Gusty winds Dust devilsfire whirls Just inland from seabreeze Well-defined convection column Thunderstorms Spotting DI approaching 70
Fire Behavior Prediction Models (eg BehavePlus)
INPUTS OUTPUTSFuel characteristics Rate of
SpreadFMC Fireline IntensitySlope Flame LengthsWind and morehellip
- Slide 9
- Slide 15
- Slide 46
-
Convection Vertical (or other direction)
movement of gas or liquid as heat rises
Heats plant foliage above surface fires and fuels ahead of the flame on steep slopes or if wind driven
Carries firebrands away from fire spotting potential
Can create enormous columns and drive fire behavior
ConvectionConvection Vertical (or other direction) movement of Vertical (or other direction) movement of
gas or liquid as heat risesgas or liquid as heat rises Heats plant foliage above surface fires Heats plant foliage above surface fires
and fuels ahead of the flame on steep and fuels ahead of the flame on steep slopes or if wind drivenslopes or if wind driven
Carries firebrands away from fire Carries firebrands away from fire spotting potentialspotting potential
Can create enormous columns and drive Can create enormous columns and drive fire behaviorfire behavior
Heat Transfer ProcessesHeat Transfer Processes
ConductionConduction Transfer by molecular activity Transfer by molecular activity
withinwithin a solid object a solid object Primary method for raising Primary method for raising
temperatures within large fuelstemperatures within large fuels Occurs between objectsfuels Occurs between objectsfuels
that are in contactthat are in contact Transfers heat in dense fuels Transfers heat in dense fuels
requiring additional heat to reach requiring additional heat to reach ignitionignition
Rate of spread (ROS) rate at which fire front advances through forest fuel (ftsec chainsmin)
Residency Time Duration for flaming combustion to pass a specific location
Flame Length amp Depth
Residency Time = Flame DepthROS
Intensity ndash rate of heat energy during combustion Reaction intensity per unit area (BTUft-2min-1) Fireline Intensity per unit length of the fire front (BTUft-1min-
1)
I = hwr
I fireline intensityh fuel heat contentw weight of fuel consumed per unit arear rate of spread
Flame Length is a good estimate of intensity
Severity Impact of fire on the environment Plants animals soils water
SE
VE
RIT
Y
INTENSITY
LOW
HIGH
HIGHLOW
Backing fire in long unburned longleaf pine
Stand replacing fire in mixed conifer forests
Head fire in frequently burned longleaf pine
Chaparral Brush Fires
1 Weather
2 Fuels 3 Topography
Surface Fuels Grasses Shrubs Litter (leaves)
Woody debris
Ground Fuels Duff (partially
decomposed)
Peat Roots Stumps
mineral soil
litter
fermentation layerhumus
Duff
Aerial Fuels Crown or canopy of
overstory
Ladder Fuels (located between crown and surface fuels)
Smaller trees Vines
Size and Shape Surface areavolume
ratio Grasses Palmetto Branches Logs
10001
401
Particle Density
Fuel Chemistry Volatile oils
Mineral Content Dampening effect on
combustion
Heat Content (stored energy)
6000-12000 BTUlb
Fuel Arrangement Vertical Grasses amp shrubs
Horizontal Litter Downed woody debris
Fuel Loading By size classes
Compactness Bulk density (fuel loadfuelbed volume)
Packing ratio (fuelbed densityparticle density)
Continuity Vertical Horizontal
ALL FUELBED PROPERTIES
Fuel Moisture Content (FMC) Large dampening effect on
combustion Heat sink
FMC changes hourly daily and seasonally
Fuel Moisture Content () = (Water Weight Dry Fuel Weight) x 100
What influences FMC In Dead Fuels Precipitation (amount
and duration) Temperature Relative humidity Wind
Equilibrium Moisture Content For a given temperature and RH dead fuel
will reach a FMC at equilibrium Environmental conditions are not constant Fuel is constantly changes FMC to reach
EMC
The lag time to reach EMC depends on particle size
Timelag categories for dead woody fuels
Timelag Class Fuel Diameter
Timelag Range (hr)
1 Hour 0-14rdquo 0-2
10 Hour frac14rdquo-1rdquo 2-20
100 Hour 1-3rdquo 20-200
1000 Hour 3-8rdquo 200-2000
Timelag or ldquoresponse timerdquo is the time it takes for 63 of the change to occur between one EMC and a second EMC when a fuel in equilibrium with a stable environmental condition is suddenly exposed to a different stable environmental condition
Small diameter fuels react quickly to hourly and daily changes Important to monitor
Large diameter fuels react more to seasonal changes California versus Florida
Fine fuels drive fire behavior
Moisture of Extinction Dead 12-40 Live gt120
Available Fuel
Florida Fine Fuel Moisture Calculation Chart
httpwwwfl-dofcomwildfirerx_traininghtmlcbc
Live Fuels FMC can be much higher than dead
fuels (100-300) Influenced by Drought (KBDI) RH Wind
Ignition of live fuels may largely depend the combustion characteristics of other fuels (eg dead surface fuels)
Duff Moisture Very dry to very moist lt30 FMC duff can burn on its own Potential for tree mortality in
burning long unburned forests May smolder for long durations May cause lots of smoke
FMCWind
Increases O2 Bends flames Increases ROS Dries fuels
convectionwind
radiation
conduction
Slopes Similar effect as
wind Bends flames ROS higher
upslope
Slope Positiontop middle bottom
Aspect
Other topographic features Valleys Box Canyons Steep draws Elevation
ELEVATION
Indicators (on a Rx burn) KBDIgt500 FMC (fine) lt7 RHlt30 Cold front approaching Gusty winds Dust devilsfire whirls Just inland from seabreeze Well-defined convection column Thunderstorms Spotting DI approaching 70
Fire Behavior Prediction Models (eg BehavePlus)
INPUTS OUTPUTSFuel characteristics Rate of
SpreadFMC Fireline IntensitySlope Flame LengthsWind and morehellip
- Slide 9
- Slide 15
- Slide 46
-
Heat Transfer ProcessesHeat Transfer Processes
ConductionConduction Transfer by molecular activity Transfer by molecular activity
withinwithin a solid object a solid object Primary method for raising Primary method for raising
temperatures within large fuelstemperatures within large fuels Occurs between objectsfuels Occurs between objectsfuels
that are in contactthat are in contact Transfers heat in dense fuels Transfers heat in dense fuels
requiring additional heat to reach requiring additional heat to reach ignitionignition
Rate of spread (ROS) rate at which fire front advances through forest fuel (ftsec chainsmin)
Residency Time Duration for flaming combustion to pass a specific location
Flame Length amp Depth
Residency Time = Flame DepthROS
Intensity ndash rate of heat energy during combustion Reaction intensity per unit area (BTUft-2min-1) Fireline Intensity per unit length of the fire front (BTUft-1min-
1)
I = hwr
I fireline intensityh fuel heat contentw weight of fuel consumed per unit arear rate of spread
Flame Length is a good estimate of intensity
Severity Impact of fire on the environment Plants animals soils water
SE
VE
RIT
Y
INTENSITY
LOW
HIGH
HIGHLOW
Backing fire in long unburned longleaf pine
Stand replacing fire in mixed conifer forests
Head fire in frequently burned longleaf pine
Chaparral Brush Fires
1 Weather
2 Fuels 3 Topography
Surface Fuels Grasses Shrubs Litter (leaves)
Woody debris
Ground Fuels Duff (partially
decomposed)
Peat Roots Stumps
mineral soil
litter
fermentation layerhumus
Duff
Aerial Fuels Crown or canopy of
overstory
Ladder Fuels (located between crown and surface fuels)
Smaller trees Vines
Size and Shape Surface areavolume
ratio Grasses Palmetto Branches Logs
10001
401
Particle Density
Fuel Chemistry Volatile oils
Mineral Content Dampening effect on
combustion
Heat Content (stored energy)
6000-12000 BTUlb
Fuel Arrangement Vertical Grasses amp shrubs
Horizontal Litter Downed woody debris
Fuel Loading By size classes
Compactness Bulk density (fuel loadfuelbed volume)
Packing ratio (fuelbed densityparticle density)
Continuity Vertical Horizontal
ALL FUELBED PROPERTIES
Fuel Moisture Content (FMC) Large dampening effect on
combustion Heat sink
FMC changes hourly daily and seasonally
Fuel Moisture Content () = (Water Weight Dry Fuel Weight) x 100
What influences FMC In Dead Fuels Precipitation (amount
and duration) Temperature Relative humidity Wind
Equilibrium Moisture Content For a given temperature and RH dead fuel
will reach a FMC at equilibrium Environmental conditions are not constant Fuel is constantly changes FMC to reach
EMC
The lag time to reach EMC depends on particle size
Timelag categories for dead woody fuels
Timelag Class Fuel Diameter
Timelag Range (hr)
1 Hour 0-14rdquo 0-2
10 Hour frac14rdquo-1rdquo 2-20
100 Hour 1-3rdquo 20-200
1000 Hour 3-8rdquo 200-2000
Timelag or ldquoresponse timerdquo is the time it takes for 63 of the change to occur between one EMC and a second EMC when a fuel in equilibrium with a stable environmental condition is suddenly exposed to a different stable environmental condition
Small diameter fuels react quickly to hourly and daily changes Important to monitor
Large diameter fuels react more to seasonal changes California versus Florida
Fine fuels drive fire behavior
Moisture of Extinction Dead 12-40 Live gt120
Available Fuel
Florida Fine Fuel Moisture Calculation Chart
httpwwwfl-dofcomwildfirerx_traininghtmlcbc
Live Fuels FMC can be much higher than dead
fuels (100-300) Influenced by Drought (KBDI) RH Wind
Ignition of live fuels may largely depend the combustion characteristics of other fuels (eg dead surface fuels)
Duff Moisture Very dry to very moist lt30 FMC duff can burn on its own Potential for tree mortality in
burning long unburned forests May smolder for long durations May cause lots of smoke
FMCWind
Increases O2 Bends flames Increases ROS Dries fuels
convectionwind
radiation
conduction
Slopes Similar effect as
wind Bends flames ROS higher
upslope
Slope Positiontop middle bottom
Aspect
Other topographic features Valleys Box Canyons Steep draws Elevation
ELEVATION
Indicators (on a Rx burn) KBDIgt500 FMC (fine) lt7 RHlt30 Cold front approaching Gusty winds Dust devilsfire whirls Just inland from seabreeze Well-defined convection column Thunderstorms Spotting DI approaching 70
Fire Behavior Prediction Models (eg BehavePlus)
INPUTS OUTPUTSFuel characteristics Rate of
SpreadFMC Fireline IntensitySlope Flame LengthsWind and morehellip
- Slide 9
- Slide 15
- Slide 46
-
Rate of spread (ROS) rate at which fire front advances through forest fuel (ftsec chainsmin)
Residency Time Duration for flaming combustion to pass a specific location
Flame Length amp Depth
Residency Time = Flame DepthROS
Intensity ndash rate of heat energy during combustion Reaction intensity per unit area (BTUft-2min-1) Fireline Intensity per unit length of the fire front (BTUft-1min-
1)
I = hwr
I fireline intensityh fuel heat contentw weight of fuel consumed per unit arear rate of spread
Flame Length is a good estimate of intensity
Severity Impact of fire on the environment Plants animals soils water
SE
VE
RIT
Y
INTENSITY
LOW
HIGH
HIGHLOW
Backing fire in long unburned longleaf pine
Stand replacing fire in mixed conifer forests
Head fire in frequently burned longleaf pine
Chaparral Brush Fires
1 Weather
2 Fuels 3 Topography
Surface Fuels Grasses Shrubs Litter (leaves)
Woody debris
Ground Fuels Duff (partially
decomposed)
Peat Roots Stumps
mineral soil
litter
fermentation layerhumus
Duff
Aerial Fuels Crown or canopy of
overstory
Ladder Fuels (located between crown and surface fuels)
Smaller trees Vines
Size and Shape Surface areavolume
ratio Grasses Palmetto Branches Logs
10001
401
Particle Density
Fuel Chemistry Volatile oils
Mineral Content Dampening effect on
combustion
Heat Content (stored energy)
6000-12000 BTUlb
Fuel Arrangement Vertical Grasses amp shrubs
Horizontal Litter Downed woody debris
Fuel Loading By size classes
Compactness Bulk density (fuel loadfuelbed volume)
Packing ratio (fuelbed densityparticle density)
Continuity Vertical Horizontal
ALL FUELBED PROPERTIES
Fuel Moisture Content (FMC) Large dampening effect on
combustion Heat sink
FMC changes hourly daily and seasonally
Fuel Moisture Content () = (Water Weight Dry Fuel Weight) x 100
What influences FMC In Dead Fuels Precipitation (amount
and duration) Temperature Relative humidity Wind
Equilibrium Moisture Content For a given temperature and RH dead fuel
will reach a FMC at equilibrium Environmental conditions are not constant Fuel is constantly changes FMC to reach
EMC
The lag time to reach EMC depends on particle size
Timelag categories for dead woody fuels
Timelag Class Fuel Diameter
Timelag Range (hr)
1 Hour 0-14rdquo 0-2
10 Hour frac14rdquo-1rdquo 2-20
100 Hour 1-3rdquo 20-200
1000 Hour 3-8rdquo 200-2000
Timelag or ldquoresponse timerdquo is the time it takes for 63 of the change to occur between one EMC and a second EMC when a fuel in equilibrium with a stable environmental condition is suddenly exposed to a different stable environmental condition
Small diameter fuels react quickly to hourly and daily changes Important to monitor
Large diameter fuels react more to seasonal changes California versus Florida
Fine fuels drive fire behavior
Moisture of Extinction Dead 12-40 Live gt120
Available Fuel
Florida Fine Fuel Moisture Calculation Chart
httpwwwfl-dofcomwildfirerx_traininghtmlcbc
Live Fuels FMC can be much higher than dead
fuels (100-300) Influenced by Drought (KBDI) RH Wind
Ignition of live fuels may largely depend the combustion characteristics of other fuels (eg dead surface fuels)
Duff Moisture Very dry to very moist lt30 FMC duff can burn on its own Potential for tree mortality in
burning long unburned forests May smolder for long durations May cause lots of smoke
FMCWind
Increases O2 Bends flames Increases ROS Dries fuels
convectionwind
radiation
conduction
Slopes Similar effect as
wind Bends flames ROS higher
upslope
Slope Positiontop middle bottom
Aspect
Other topographic features Valleys Box Canyons Steep draws Elevation
ELEVATION
Indicators (on a Rx burn) KBDIgt500 FMC (fine) lt7 RHlt30 Cold front approaching Gusty winds Dust devilsfire whirls Just inland from seabreeze Well-defined convection column Thunderstorms Spotting DI approaching 70
Fire Behavior Prediction Models (eg BehavePlus)
INPUTS OUTPUTSFuel characteristics Rate of
SpreadFMC Fireline IntensitySlope Flame LengthsWind and morehellip
- Slide 9
- Slide 15
- Slide 46
-
Intensity ndash rate of heat energy during combustion Reaction intensity per unit area (BTUft-2min-1) Fireline Intensity per unit length of the fire front (BTUft-1min-
1)
I = hwr
I fireline intensityh fuel heat contentw weight of fuel consumed per unit arear rate of spread
Flame Length is a good estimate of intensity
Severity Impact of fire on the environment Plants animals soils water
SE
VE
RIT
Y
INTENSITY
LOW
HIGH
HIGHLOW
Backing fire in long unburned longleaf pine
Stand replacing fire in mixed conifer forests
Head fire in frequently burned longleaf pine
Chaparral Brush Fires
1 Weather
2 Fuels 3 Topography
Surface Fuels Grasses Shrubs Litter (leaves)
Woody debris
Ground Fuels Duff (partially
decomposed)
Peat Roots Stumps
mineral soil
litter
fermentation layerhumus
Duff
Aerial Fuels Crown or canopy of
overstory
Ladder Fuels (located between crown and surface fuels)
Smaller trees Vines
Size and Shape Surface areavolume
ratio Grasses Palmetto Branches Logs
10001
401
Particle Density
Fuel Chemistry Volatile oils
Mineral Content Dampening effect on
combustion
Heat Content (stored energy)
6000-12000 BTUlb
Fuel Arrangement Vertical Grasses amp shrubs
Horizontal Litter Downed woody debris
Fuel Loading By size classes
Compactness Bulk density (fuel loadfuelbed volume)
Packing ratio (fuelbed densityparticle density)
Continuity Vertical Horizontal
ALL FUELBED PROPERTIES
Fuel Moisture Content (FMC) Large dampening effect on
combustion Heat sink
FMC changes hourly daily and seasonally
Fuel Moisture Content () = (Water Weight Dry Fuel Weight) x 100
What influences FMC In Dead Fuels Precipitation (amount
and duration) Temperature Relative humidity Wind
Equilibrium Moisture Content For a given temperature and RH dead fuel
will reach a FMC at equilibrium Environmental conditions are not constant Fuel is constantly changes FMC to reach
EMC
The lag time to reach EMC depends on particle size
Timelag categories for dead woody fuels
Timelag Class Fuel Diameter
Timelag Range (hr)
1 Hour 0-14rdquo 0-2
10 Hour frac14rdquo-1rdquo 2-20
100 Hour 1-3rdquo 20-200
1000 Hour 3-8rdquo 200-2000
Timelag or ldquoresponse timerdquo is the time it takes for 63 of the change to occur between one EMC and a second EMC when a fuel in equilibrium with a stable environmental condition is suddenly exposed to a different stable environmental condition
Small diameter fuels react quickly to hourly and daily changes Important to monitor
Large diameter fuels react more to seasonal changes California versus Florida
Fine fuels drive fire behavior
Moisture of Extinction Dead 12-40 Live gt120
Available Fuel
Florida Fine Fuel Moisture Calculation Chart
httpwwwfl-dofcomwildfirerx_traininghtmlcbc
Live Fuels FMC can be much higher than dead
fuels (100-300) Influenced by Drought (KBDI) RH Wind
Ignition of live fuels may largely depend the combustion characteristics of other fuels (eg dead surface fuels)
Duff Moisture Very dry to very moist lt30 FMC duff can burn on its own Potential for tree mortality in
burning long unburned forests May smolder for long durations May cause lots of smoke
FMCWind
Increases O2 Bends flames Increases ROS Dries fuels
convectionwind
radiation
conduction
Slopes Similar effect as
wind Bends flames ROS higher
upslope
Slope Positiontop middle bottom
Aspect
Other topographic features Valleys Box Canyons Steep draws Elevation
ELEVATION
Indicators (on a Rx burn) KBDIgt500 FMC (fine) lt7 RHlt30 Cold front approaching Gusty winds Dust devilsfire whirls Just inland from seabreeze Well-defined convection column Thunderstorms Spotting DI approaching 70
Fire Behavior Prediction Models (eg BehavePlus)
INPUTS OUTPUTSFuel characteristics Rate of
SpreadFMC Fireline IntensitySlope Flame LengthsWind and morehellip
- Slide 9
- Slide 15
- Slide 46
-
Severity Impact of fire on the environment Plants animals soils water
SE
VE
RIT
Y
INTENSITY
LOW
HIGH
HIGHLOW
Backing fire in long unburned longleaf pine
Stand replacing fire in mixed conifer forests
Head fire in frequently burned longleaf pine
Chaparral Brush Fires
1 Weather
2 Fuels 3 Topography
Surface Fuels Grasses Shrubs Litter (leaves)
Woody debris
Ground Fuels Duff (partially
decomposed)
Peat Roots Stumps
mineral soil
litter
fermentation layerhumus
Duff
Aerial Fuels Crown or canopy of
overstory
Ladder Fuels (located between crown and surface fuels)
Smaller trees Vines
Size and Shape Surface areavolume
ratio Grasses Palmetto Branches Logs
10001
401
Particle Density
Fuel Chemistry Volatile oils
Mineral Content Dampening effect on
combustion
Heat Content (stored energy)
6000-12000 BTUlb
Fuel Arrangement Vertical Grasses amp shrubs
Horizontal Litter Downed woody debris
Fuel Loading By size classes
Compactness Bulk density (fuel loadfuelbed volume)
Packing ratio (fuelbed densityparticle density)
Continuity Vertical Horizontal
ALL FUELBED PROPERTIES
Fuel Moisture Content (FMC) Large dampening effect on
combustion Heat sink
FMC changes hourly daily and seasonally
Fuel Moisture Content () = (Water Weight Dry Fuel Weight) x 100
What influences FMC In Dead Fuels Precipitation (amount
and duration) Temperature Relative humidity Wind
Equilibrium Moisture Content For a given temperature and RH dead fuel
will reach a FMC at equilibrium Environmental conditions are not constant Fuel is constantly changes FMC to reach
EMC
The lag time to reach EMC depends on particle size
Timelag categories for dead woody fuels
Timelag Class Fuel Diameter
Timelag Range (hr)
1 Hour 0-14rdquo 0-2
10 Hour frac14rdquo-1rdquo 2-20
100 Hour 1-3rdquo 20-200
1000 Hour 3-8rdquo 200-2000
Timelag or ldquoresponse timerdquo is the time it takes for 63 of the change to occur between one EMC and a second EMC when a fuel in equilibrium with a stable environmental condition is suddenly exposed to a different stable environmental condition
Small diameter fuels react quickly to hourly and daily changes Important to monitor
Large diameter fuels react more to seasonal changes California versus Florida
Fine fuels drive fire behavior
Moisture of Extinction Dead 12-40 Live gt120
Available Fuel
Florida Fine Fuel Moisture Calculation Chart
httpwwwfl-dofcomwildfirerx_traininghtmlcbc
Live Fuels FMC can be much higher than dead
fuels (100-300) Influenced by Drought (KBDI) RH Wind
Ignition of live fuels may largely depend the combustion characteristics of other fuels (eg dead surface fuels)
Duff Moisture Very dry to very moist lt30 FMC duff can burn on its own Potential for tree mortality in
burning long unburned forests May smolder for long durations May cause lots of smoke
FMCWind
Increases O2 Bends flames Increases ROS Dries fuels
convectionwind
radiation
conduction
Slopes Similar effect as
wind Bends flames ROS higher
upslope
Slope Positiontop middle bottom
Aspect
Other topographic features Valleys Box Canyons Steep draws Elevation
ELEVATION
Indicators (on a Rx burn) KBDIgt500 FMC (fine) lt7 RHlt30 Cold front approaching Gusty winds Dust devilsfire whirls Just inland from seabreeze Well-defined convection column Thunderstorms Spotting DI approaching 70
Fire Behavior Prediction Models (eg BehavePlus)
INPUTS OUTPUTSFuel characteristics Rate of
SpreadFMC Fireline IntensitySlope Flame LengthsWind and morehellip
- Slide 9
- Slide 15
- Slide 46
-
1 Weather
2 Fuels 3 Topography
Surface Fuels Grasses Shrubs Litter (leaves)
Woody debris
Ground Fuels Duff (partially
decomposed)
Peat Roots Stumps
mineral soil
litter
fermentation layerhumus
Duff
Aerial Fuels Crown or canopy of
overstory
Ladder Fuels (located between crown and surface fuels)
Smaller trees Vines
Size and Shape Surface areavolume
ratio Grasses Palmetto Branches Logs
10001
401
Particle Density
Fuel Chemistry Volatile oils
Mineral Content Dampening effect on
combustion
Heat Content (stored energy)
6000-12000 BTUlb
Fuel Arrangement Vertical Grasses amp shrubs
Horizontal Litter Downed woody debris
Fuel Loading By size classes
Compactness Bulk density (fuel loadfuelbed volume)
Packing ratio (fuelbed densityparticle density)
Continuity Vertical Horizontal
ALL FUELBED PROPERTIES
Fuel Moisture Content (FMC) Large dampening effect on
combustion Heat sink
FMC changes hourly daily and seasonally
Fuel Moisture Content () = (Water Weight Dry Fuel Weight) x 100
What influences FMC In Dead Fuels Precipitation (amount
and duration) Temperature Relative humidity Wind
Equilibrium Moisture Content For a given temperature and RH dead fuel
will reach a FMC at equilibrium Environmental conditions are not constant Fuel is constantly changes FMC to reach
EMC
The lag time to reach EMC depends on particle size
Timelag categories for dead woody fuels
Timelag Class Fuel Diameter
Timelag Range (hr)
1 Hour 0-14rdquo 0-2
10 Hour frac14rdquo-1rdquo 2-20
100 Hour 1-3rdquo 20-200
1000 Hour 3-8rdquo 200-2000
Timelag or ldquoresponse timerdquo is the time it takes for 63 of the change to occur between one EMC and a second EMC when a fuel in equilibrium with a stable environmental condition is suddenly exposed to a different stable environmental condition
Small diameter fuels react quickly to hourly and daily changes Important to monitor
Large diameter fuels react more to seasonal changes California versus Florida
Fine fuels drive fire behavior
Moisture of Extinction Dead 12-40 Live gt120
Available Fuel
Florida Fine Fuel Moisture Calculation Chart
httpwwwfl-dofcomwildfirerx_traininghtmlcbc
Live Fuels FMC can be much higher than dead
fuels (100-300) Influenced by Drought (KBDI) RH Wind
Ignition of live fuels may largely depend the combustion characteristics of other fuels (eg dead surface fuels)
Duff Moisture Very dry to very moist lt30 FMC duff can burn on its own Potential for tree mortality in
burning long unburned forests May smolder for long durations May cause lots of smoke
FMCWind
Increases O2 Bends flames Increases ROS Dries fuels
convectionwind
radiation
conduction
Slopes Similar effect as
wind Bends flames ROS higher
upslope
Slope Positiontop middle bottom
Aspect
Other topographic features Valleys Box Canyons Steep draws Elevation
ELEVATION
Indicators (on a Rx burn) KBDIgt500 FMC (fine) lt7 RHlt30 Cold front approaching Gusty winds Dust devilsfire whirls Just inland from seabreeze Well-defined convection column Thunderstorms Spotting DI approaching 70
Fire Behavior Prediction Models (eg BehavePlus)
INPUTS OUTPUTSFuel characteristics Rate of
SpreadFMC Fireline IntensitySlope Flame LengthsWind and morehellip
- Slide 9
- Slide 15
- Slide 46
-
Surface Fuels Grasses Shrubs Litter (leaves)
Woody debris
Ground Fuels Duff (partially
decomposed)
Peat Roots Stumps
mineral soil
litter
fermentation layerhumus
Duff
Aerial Fuels Crown or canopy of
overstory
Ladder Fuels (located between crown and surface fuels)
Smaller trees Vines
Size and Shape Surface areavolume
ratio Grasses Palmetto Branches Logs
10001
401
Particle Density
Fuel Chemistry Volatile oils
Mineral Content Dampening effect on
combustion
Heat Content (stored energy)
6000-12000 BTUlb
Fuel Arrangement Vertical Grasses amp shrubs
Horizontal Litter Downed woody debris
Fuel Loading By size classes
Compactness Bulk density (fuel loadfuelbed volume)
Packing ratio (fuelbed densityparticle density)
Continuity Vertical Horizontal
ALL FUELBED PROPERTIES
Fuel Moisture Content (FMC) Large dampening effect on
combustion Heat sink
FMC changes hourly daily and seasonally
Fuel Moisture Content () = (Water Weight Dry Fuel Weight) x 100
What influences FMC In Dead Fuels Precipitation (amount
and duration) Temperature Relative humidity Wind
Equilibrium Moisture Content For a given temperature and RH dead fuel
will reach a FMC at equilibrium Environmental conditions are not constant Fuel is constantly changes FMC to reach
EMC
The lag time to reach EMC depends on particle size
Timelag categories for dead woody fuels
Timelag Class Fuel Diameter
Timelag Range (hr)
1 Hour 0-14rdquo 0-2
10 Hour frac14rdquo-1rdquo 2-20
100 Hour 1-3rdquo 20-200
1000 Hour 3-8rdquo 200-2000
Timelag or ldquoresponse timerdquo is the time it takes for 63 of the change to occur between one EMC and a second EMC when a fuel in equilibrium with a stable environmental condition is suddenly exposed to a different stable environmental condition
Small diameter fuels react quickly to hourly and daily changes Important to monitor
Large diameter fuels react more to seasonal changes California versus Florida
Fine fuels drive fire behavior
Moisture of Extinction Dead 12-40 Live gt120
Available Fuel
Florida Fine Fuel Moisture Calculation Chart
httpwwwfl-dofcomwildfirerx_traininghtmlcbc
Live Fuels FMC can be much higher than dead
fuels (100-300) Influenced by Drought (KBDI) RH Wind
Ignition of live fuels may largely depend the combustion characteristics of other fuels (eg dead surface fuels)
Duff Moisture Very dry to very moist lt30 FMC duff can burn on its own Potential for tree mortality in
burning long unburned forests May smolder for long durations May cause lots of smoke
FMCWind
Increases O2 Bends flames Increases ROS Dries fuels
convectionwind
radiation
conduction
Slopes Similar effect as
wind Bends flames ROS higher
upslope
Slope Positiontop middle bottom
Aspect
Other topographic features Valleys Box Canyons Steep draws Elevation
ELEVATION
Indicators (on a Rx burn) KBDIgt500 FMC (fine) lt7 RHlt30 Cold front approaching Gusty winds Dust devilsfire whirls Just inland from seabreeze Well-defined convection column Thunderstorms Spotting DI approaching 70
Fire Behavior Prediction Models (eg BehavePlus)
INPUTS OUTPUTSFuel characteristics Rate of
SpreadFMC Fireline IntensitySlope Flame LengthsWind and morehellip
- Slide 9
- Slide 15
- Slide 46
-
Ground Fuels Duff (partially
decomposed)
Peat Roots Stumps
mineral soil
litter
fermentation layerhumus
Duff
Aerial Fuels Crown or canopy of
overstory
Ladder Fuels (located between crown and surface fuels)
Smaller trees Vines
Size and Shape Surface areavolume
ratio Grasses Palmetto Branches Logs
10001
401
Particle Density
Fuel Chemistry Volatile oils
Mineral Content Dampening effect on
combustion
Heat Content (stored energy)
6000-12000 BTUlb
Fuel Arrangement Vertical Grasses amp shrubs
Horizontal Litter Downed woody debris
Fuel Loading By size classes
Compactness Bulk density (fuel loadfuelbed volume)
Packing ratio (fuelbed densityparticle density)
Continuity Vertical Horizontal
ALL FUELBED PROPERTIES
Fuel Moisture Content (FMC) Large dampening effect on
combustion Heat sink
FMC changes hourly daily and seasonally
Fuel Moisture Content () = (Water Weight Dry Fuel Weight) x 100
What influences FMC In Dead Fuels Precipitation (amount
and duration) Temperature Relative humidity Wind
Equilibrium Moisture Content For a given temperature and RH dead fuel
will reach a FMC at equilibrium Environmental conditions are not constant Fuel is constantly changes FMC to reach
EMC
The lag time to reach EMC depends on particle size
Timelag categories for dead woody fuels
Timelag Class Fuel Diameter
Timelag Range (hr)
1 Hour 0-14rdquo 0-2
10 Hour frac14rdquo-1rdquo 2-20
100 Hour 1-3rdquo 20-200
1000 Hour 3-8rdquo 200-2000
Timelag or ldquoresponse timerdquo is the time it takes for 63 of the change to occur between one EMC and a second EMC when a fuel in equilibrium with a stable environmental condition is suddenly exposed to a different stable environmental condition
Small diameter fuels react quickly to hourly and daily changes Important to monitor
Large diameter fuels react more to seasonal changes California versus Florida
Fine fuels drive fire behavior
Moisture of Extinction Dead 12-40 Live gt120
Available Fuel
Florida Fine Fuel Moisture Calculation Chart
httpwwwfl-dofcomwildfirerx_traininghtmlcbc
Live Fuels FMC can be much higher than dead
fuels (100-300) Influenced by Drought (KBDI) RH Wind
Ignition of live fuels may largely depend the combustion characteristics of other fuels (eg dead surface fuels)
Duff Moisture Very dry to very moist lt30 FMC duff can burn on its own Potential for tree mortality in
burning long unburned forests May smolder for long durations May cause lots of smoke
FMCWind
Increases O2 Bends flames Increases ROS Dries fuels
convectionwind
radiation
conduction
Slopes Similar effect as
wind Bends flames ROS higher
upslope
Slope Positiontop middle bottom
Aspect
Other topographic features Valleys Box Canyons Steep draws Elevation
ELEVATION
Indicators (on a Rx burn) KBDIgt500 FMC (fine) lt7 RHlt30 Cold front approaching Gusty winds Dust devilsfire whirls Just inland from seabreeze Well-defined convection column Thunderstorms Spotting DI approaching 70
Fire Behavior Prediction Models (eg BehavePlus)
INPUTS OUTPUTSFuel characteristics Rate of
SpreadFMC Fireline IntensitySlope Flame LengthsWind and morehellip
- Slide 9
- Slide 15
- Slide 46
-
Aerial Fuels Crown or canopy of
overstory
Ladder Fuels (located between crown and surface fuels)
Smaller trees Vines
Size and Shape Surface areavolume
ratio Grasses Palmetto Branches Logs
10001
401
Particle Density
Fuel Chemistry Volatile oils
Mineral Content Dampening effect on
combustion
Heat Content (stored energy)
6000-12000 BTUlb
Fuel Arrangement Vertical Grasses amp shrubs
Horizontal Litter Downed woody debris
Fuel Loading By size classes
Compactness Bulk density (fuel loadfuelbed volume)
Packing ratio (fuelbed densityparticle density)
Continuity Vertical Horizontal
ALL FUELBED PROPERTIES
Fuel Moisture Content (FMC) Large dampening effect on
combustion Heat sink
FMC changes hourly daily and seasonally
Fuel Moisture Content () = (Water Weight Dry Fuel Weight) x 100
What influences FMC In Dead Fuels Precipitation (amount
and duration) Temperature Relative humidity Wind
Equilibrium Moisture Content For a given temperature and RH dead fuel
will reach a FMC at equilibrium Environmental conditions are not constant Fuel is constantly changes FMC to reach
EMC
The lag time to reach EMC depends on particle size
Timelag categories for dead woody fuels
Timelag Class Fuel Diameter
Timelag Range (hr)
1 Hour 0-14rdquo 0-2
10 Hour frac14rdquo-1rdquo 2-20
100 Hour 1-3rdquo 20-200
1000 Hour 3-8rdquo 200-2000
Timelag or ldquoresponse timerdquo is the time it takes for 63 of the change to occur between one EMC and a second EMC when a fuel in equilibrium with a stable environmental condition is suddenly exposed to a different stable environmental condition
Small diameter fuels react quickly to hourly and daily changes Important to monitor
Large diameter fuels react more to seasonal changes California versus Florida
Fine fuels drive fire behavior
Moisture of Extinction Dead 12-40 Live gt120
Available Fuel
Florida Fine Fuel Moisture Calculation Chart
httpwwwfl-dofcomwildfirerx_traininghtmlcbc
Live Fuels FMC can be much higher than dead
fuels (100-300) Influenced by Drought (KBDI) RH Wind
Ignition of live fuels may largely depend the combustion characteristics of other fuels (eg dead surface fuels)
Duff Moisture Very dry to very moist lt30 FMC duff can burn on its own Potential for tree mortality in
burning long unburned forests May smolder for long durations May cause lots of smoke
FMCWind
Increases O2 Bends flames Increases ROS Dries fuels
convectionwind
radiation
conduction
Slopes Similar effect as
wind Bends flames ROS higher
upslope
Slope Positiontop middle bottom
Aspect
Other topographic features Valleys Box Canyons Steep draws Elevation
ELEVATION
Indicators (on a Rx burn) KBDIgt500 FMC (fine) lt7 RHlt30 Cold front approaching Gusty winds Dust devilsfire whirls Just inland from seabreeze Well-defined convection column Thunderstorms Spotting DI approaching 70
Fire Behavior Prediction Models (eg BehavePlus)
INPUTS OUTPUTSFuel characteristics Rate of
SpreadFMC Fireline IntensitySlope Flame LengthsWind and morehellip
- Slide 9
- Slide 15
- Slide 46
-
Size and Shape Surface areavolume
ratio Grasses Palmetto Branches Logs
10001
401
Particle Density
Fuel Chemistry Volatile oils
Mineral Content Dampening effect on
combustion
Heat Content (stored energy)
6000-12000 BTUlb
Fuel Arrangement Vertical Grasses amp shrubs
Horizontal Litter Downed woody debris
Fuel Loading By size classes
Compactness Bulk density (fuel loadfuelbed volume)
Packing ratio (fuelbed densityparticle density)
Continuity Vertical Horizontal
ALL FUELBED PROPERTIES
Fuel Moisture Content (FMC) Large dampening effect on
combustion Heat sink
FMC changes hourly daily and seasonally
Fuel Moisture Content () = (Water Weight Dry Fuel Weight) x 100
What influences FMC In Dead Fuels Precipitation (amount
and duration) Temperature Relative humidity Wind
Equilibrium Moisture Content For a given temperature and RH dead fuel
will reach a FMC at equilibrium Environmental conditions are not constant Fuel is constantly changes FMC to reach
EMC
The lag time to reach EMC depends on particle size
Timelag categories for dead woody fuels
Timelag Class Fuel Diameter
Timelag Range (hr)
1 Hour 0-14rdquo 0-2
10 Hour frac14rdquo-1rdquo 2-20
100 Hour 1-3rdquo 20-200
1000 Hour 3-8rdquo 200-2000
Timelag or ldquoresponse timerdquo is the time it takes for 63 of the change to occur between one EMC and a second EMC when a fuel in equilibrium with a stable environmental condition is suddenly exposed to a different stable environmental condition
Small diameter fuels react quickly to hourly and daily changes Important to monitor
Large diameter fuels react more to seasonal changes California versus Florida
Fine fuels drive fire behavior
Moisture of Extinction Dead 12-40 Live gt120
Available Fuel
Florida Fine Fuel Moisture Calculation Chart
httpwwwfl-dofcomwildfirerx_traininghtmlcbc
Live Fuels FMC can be much higher than dead
fuels (100-300) Influenced by Drought (KBDI) RH Wind
Ignition of live fuels may largely depend the combustion characteristics of other fuels (eg dead surface fuels)
Duff Moisture Very dry to very moist lt30 FMC duff can burn on its own Potential for tree mortality in
burning long unburned forests May smolder for long durations May cause lots of smoke
FMCWind
Increases O2 Bends flames Increases ROS Dries fuels
convectionwind
radiation
conduction
Slopes Similar effect as
wind Bends flames ROS higher
upslope
Slope Positiontop middle bottom
Aspect
Other topographic features Valleys Box Canyons Steep draws Elevation
ELEVATION
Indicators (on a Rx burn) KBDIgt500 FMC (fine) lt7 RHlt30 Cold front approaching Gusty winds Dust devilsfire whirls Just inland from seabreeze Well-defined convection column Thunderstorms Spotting DI approaching 70
Fire Behavior Prediction Models (eg BehavePlus)
INPUTS OUTPUTSFuel characteristics Rate of
SpreadFMC Fireline IntensitySlope Flame LengthsWind and morehellip
- Slide 9
- Slide 15
- Slide 46
-
Fuel Chemistry Volatile oils
Mineral Content Dampening effect on
combustion
Heat Content (stored energy)
6000-12000 BTUlb
Fuel Arrangement Vertical Grasses amp shrubs
Horizontal Litter Downed woody debris
Fuel Loading By size classes
Compactness Bulk density (fuel loadfuelbed volume)
Packing ratio (fuelbed densityparticle density)
Continuity Vertical Horizontal
ALL FUELBED PROPERTIES
Fuel Moisture Content (FMC) Large dampening effect on
combustion Heat sink
FMC changes hourly daily and seasonally
Fuel Moisture Content () = (Water Weight Dry Fuel Weight) x 100
What influences FMC In Dead Fuels Precipitation (amount
and duration) Temperature Relative humidity Wind
Equilibrium Moisture Content For a given temperature and RH dead fuel
will reach a FMC at equilibrium Environmental conditions are not constant Fuel is constantly changes FMC to reach
EMC
The lag time to reach EMC depends on particle size
Timelag categories for dead woody fuels
Timelag Class Fuel Diameter
Timelag Range (hr)
1 Hour 0-14rdquo 0-2
10 Hour frac14rdquo-1rdquo 2-20
100 Hour 1-3rdquo 20-200
1000 Hour 3-8rdquo 200-2000
Timelag or ldquoresponse timerdquo is the time it takes for 63 of the change to occur between one EMC and a second EMC when a fuel in equilibrium with a stable environmental condition is suddenly exposed to a different stable environmental condition
Small diameter fuels react quickly to hourly and daily changes Important to monitor
Large diameter fuels react more to seasonal changes California versus Florida
Fine fuels drive fire behavior
Moisture of Extinction Dead 12-40 Live gt120
Available Fuel
Florida Fine Fuel Moisture Calculation Chart
httpwwwfl-dofcomwildfirerx_traininghtmlcbc
Live Fuels FMC can be much higher than dead
fuels (100-300) Influenced by Drought (KBDI) RH Wind
Ignition of live fuels may largely depend the combustion characteristics of other fuels (eg dead surface fuels)
Duff Moisture Very dry to very moist lt30 FMC duff can burn on its own Potential for tree mortality in
burning long unburned forests May smolder for long durations May cause lots of smoke
FMCWind
Increases O2 Bends flames Increases ROS Dries fuels
convectionwind
radiation
conduction
Slopes Similar effect as
wind Bends flames ROS higher
upslope
Slope Positiontop middle bottom
Aspect
Other topographic features Valleys Box Canyons Steep draws Elevation
ELEVATION
Indicators (on a Rx burn) KBDIgt500 FMC (fine) lt7 RHlt30 Cold front approaching Gusty winds Dust devilsfire whirls Just inland from seabreeze Well-defined convection column Thunderstorms Spotting DI approaching 70
Fire Behavior Prediction Models (eg BehavePlus)
INPUTS OUTPUTSFuel characteristics Rate of
SpreadFMC Fireline IntensitySlope Flame LengthsWind and morehellip
- Slide 9
- Slide 15
- Slide 46
-
Fuel Arrangement Vertical Grasses amp shrubs
Horizontal Litter Downed woody debris
Fuel Loading By size classes
Compactness Bulk density (fuel loadfuelbed volume)
Packing ratio (fuelbed densityparticle density)
Continuity Vertical Horizontal
ALL FUELBED PROPERTIES
Fuel Moisture Content (FMC) Large dampening effect on
combustion Heat sink
FMC changes hourly daily and seasonally
Fuel Moisture Content () = (Water Weight Dry Fuel Weight) x 100
What influences FMC In Dead Fuels Precipitation (amount
and duration) Temperature Relative humidity Wind
Equilibrium Moisture Content For a given temperature and RH dead fuel
will reach a FMC at equilibrium Environmental conditions are not constant Fuel is constantly changes FMC to reach
EMC
The lag time to reach EMC depends on particle size
Timelag categories for dead woody fuels
Timelag Class Fuel Diameter
Timelag Range (hr)
1 Hour 0-14rdquo 0-2
10 Hour frac14rdquo-1rdquo 2-20
100 Hour 1-3rdquo 20-200
1000 Hour 3-8rdquo 200-2000
Timelag or ldquoresponse timerdquo is the time it takes for 63 of the change to occur between one EMC and a second EMC when a fuel in equilibrium with a stable environmental condition is suddenly exposed to a different stable environmental condition
Small diameter fuels react quickly to hourly and daily changes Important to monitor
Large diameter fuels react more to seasonal changes California versus Florida
Fine fuels drive fire behavior
Moisture of Extinction Dead 12-40 Live gt120
Available Fuel
Florida Fine Fuel Moisture Calculation Chart
httpwwwfl-dofcomwildfirerx_traininghtmlcbc
Live Fuels FMC can be much higher than dead
fuels (100-300) Influenced by Drought (KBDI) RH Wind
Ignition of live fuels may largely depend the combustion characteristics of other fuels (eg dead surface fuels)
Duff Moisture Very dry to very moist lt30 FMC duff can burn on its own Potential for tree mortality in
burning long unburned forests May smolder for long durations May cause lots of smoke
FMCWind
Increases O2 Bends flames Increases ROS Dries fuels
convectionwind
radiation
conduction
Slopes Similar effect as
wind Bends flames ROS higher
upslope
Slope Positiontop middle bottom
Aspect
Other topographic features Valleys Box Canyons Steep draws Elevation
ELEVATION
Indicators (on a Rx burn) KBDIgt500 FMC (fine) lt7 RHlt30 Cold front approaching Gusty winds Dust devilsfire whirls Just inland from seabreeze Well-defined convection column Thunderstorms Spotting DI approaching 70
Fire Behavior Prediction Models (eg BehavePlus)
INPUTS OUTPUTSFuel characteristics Rate of
SpreadFMC Fireline IntensitySlope Flame LengthsWind and morehellip
- Slide 9
- Slide 15
- Slide 46
-
Fuel Loading By size classes
Compactness Bulk density (fuel loadfuelbed volume)
Packing ratio (fuelbed densityparticle density)
Continuity Vertical Horizontal
ALL FUELBED PROPERTIES
Fuel Moisture Content (FMC) Large dampening effect on
combustion Heat sink
FMC changes hourly daily and seasonally
Fuel Moisture Content () = (Water Weight Dry Fuel Weight) x 100
What influences FMC In Dead Fuels Precipitation (amount
and duration) Temperature Relative humidity Wind
Equilibrium Moisture Content For a given temperature and RH dead fuel
will reach a FMC at equilibrium Environmental conditions are not constant Fuel is constantly changes FMC to reach
EMC
The lag time to reach EMC depends on particle size
Timelag categories for dead woody fuels
Timelag Class Fuel Diameter
Timelag Range (hr)
1 Hour 0-14rdquo 0-2
10 Hour frac14rdquo-1rdquo 2-20
100 Hour 1-3rdquo 20-200
1000 Hour 3-8rdquo 200-2000
Timelag or ldquoresponse timerdquo is the time it takes for 63 of the change to occur between one EMC and a second EMC when a fuel in equilibrium with a stable environmental condition is suddenly exposed to a different stable environmental condition
Small diameter fuels react quickly to hourly and daily changes Important to monitor
Large diameter fuels react more to seasonal changes California versus Florida
Fine fuels drive fire behavior
Moisture of Extinction Dead 12-40 Live gt120
Available Fuel
Florida Fine Fuel Moisture Calculation Chart
httpwwwfl-dofcomwildfirerx_traininghtmlcbc
Live Fuels FMC can be much higher than dead
fuels (100-300) Influenced by Drought (KBDI) RH Wind
Ignition of live fuels may largely depend the combustion characteristics of other fuels (eg dead surface fuels)
Duff Moisture Very dry to very moist lt30 FMC duff can burn on its own Potential for tree mortality in
burning long unburned forests May smolder for long durations May cause lots of smoke
FMCWind
Increases O2 Bends flames Increases ROS Dries fuels
convectionwind
radiation
conduction
Slopes Similar effect as
wind Bends flames ROS higher
upslope
Slope Positiontop middle bottom
Aspect
Other topographic features Valleys Box Canyons Steep draws Elevation
ELEVATION
Indicators (on a Rx burn) KBDIgt500 FMC (fine) lt7 RHlt30 Cold front approaching Gusty winds Dust devilsfire whirls Just inland from seabreeze Well-defined convection column Thunderstorms Spotting DI approaching 70
Fire Behavior Prediction Models (eg BehavePlus)
INPUTS OUTPUTSFuel characteristics Rate of
SpreadFMC Fireline IntensitySlope Flame LengthsWind and morehellip
- Slide 9
- Slide 15
- Slide 46
-
Fuel Moisture Content (FMC) Large dampening effect on
combustion Heat sink
FMC changes hourly daily and seasonally
Fuel Moisture Content () = (Water Weight Dry Fuel Weight) x 100
What influences FMC In Dead Fuels Precipitation (amount
and duration) Temperature Relative humidity Wind
Equilibrium Moisture Content For a given temperature and RH dead fuel
will reach a FMC at equilibrium Environmental conditions are not constant Fuel is constantly changes FMC to reach
EMC
The lag time to reach EMC depends on particle size
Timelag categories for dead woody fuels
Timelag Class Fuel Diameter
Timelag Range (hr)
1 Hour 0-14rdquo 0-2
10 Hour frac14rdquo-1rdquo 2-20
100 Hour 1-3rdquo 20-200
1000 Hour 3-8rdquo 200-2000
Timelag or ldquoresponse timerdquo is the time it takes for 63 of the change to occur between one EMC and a second EMC when a fuel in equilibrium with a stable environmental condition is suddenly exposed to a different stable environmental condition
Small diameter fuels react quickly to hourly and daily changes Important to monitor
Large diameter fuels react more to seasonal changes California versus Florida
Fine fuels drive fire behavior
Moisture of Extinction Dead 12-40 Live gt120
Available Fuel
Florida Fine Fuel Moisture Calculation Chart
httpwwwfl-dofcomwildfirerx_traininghtmlcbc
Live Fuels FMC can be much higher than dead
fuels (100-300) Influenced by Drought (KBDI) RH Wind
Ignition of live fuels may largely depend the combustion characteristics of other fuels (eg dead surface fuels)
Duff Moisture Very dry to very moist lt30 FMC duff can burn on its own Potential for tree mortality in
burning long unburned forests May smolder for long durations May cause lots of smoke
FMCWind
Increases O2 Bends flames Increases ROS Dries fuels
convectionwind
radiation
conduction
Slopes Similar effect as
wind Bends flames ROS higher
upslope
Slope Positiontop middle bottom
Aspect
Other topographic features Valleys Box Canyons Steep draws Elevation
ELEVATION
Indicators (on a Rx burn) KBDIgt500 FMC (fine) lt7 RHlt30 Cold front approaching Gusty winds Dust devilsfire whirls Just inland from seabreeze Well-defined convection column Thunderstorms Spotting DI approaching 70
Fire Behavior Prediction Models (eg BehavePlus)
INPUTS OUTPUTSFuel characteristics Rate of
SpreadFMC Fireline IntensitySlope Flame LengthsWind and morehellip
- Slide 9
- Slide 15
- Slide 46
-
What influences FMC In Dead Fuels Precipitation (amount
and duration) Temperature Relative humidity Wind
Equilibrium Moisture Content For a given temperature and RH dead fuel
will reach a FMC at equilibrium Environmental conditions are not constant Fuel is constantly changes FMC to reach
EMC
The lag time to reach EMC depends on particle size
Timelag categories for dead woody fuels
Timelag Class Fuel Diameter
Timelag Range (hr)
1 Hour 0-14rdquo 0-2
10 Hour frac14rdquo-1rdquo 2-20
100 Hour 1-3rdquo 20-200
1000 Hour 3-8rdquo 200-2000
Timelag or ldquoresponse timerdquo is the time it takes for 63 of the change to occur between one EMC and a second EMC when a fuel in equilibrium with a stable environmental condition is suddenly exposed to a different stable environmental condition
Small diameter fuels react quickly to hourly and daily changes Important to monitor
Large diameter fuels react more to seasonal changes California versus Florida
Fine fuels drive fire behavior
Moisture of Extinction Dead 12-40 Live gt120
Available Fuel
Florida Fine Fuel Moisture Calculation Chart
httpwwwfl-dofcomwildfirerx_traininghtmlcbc
Live Fuels FMC can be much higher than dead
fuels (100-300) Influenced by Drought (KBDI) RH Wind
Ignition of live fuels may largely depend the combustion characteristics of other fuels (eg dead surface fuels)
Duff Moisture Very dry to very moist lt30 FMC duff can burn on its own Potential for tree mortality in
burning long unburned forests May smolder for long durations May cause lots of smoke
FMCWind
Increases O2 Bends flames Increases ROS Dries fuels
convectionwind
radiation
conduction
Slopes Similar effect as
wind Bends flames ROS higher
upslope
Slope Positiontop middle bottom
Aspect
Other topographic features Valleys Box Canyons Steep draws Elevation
ELEVATION
Indicators (on a Rx burn) KBDIgt500 FMC (fine) lt7 RHlt30 Cold front approaching Gusty winds Dust devilsfire whirls Just inland from seabreeze Well-defined convection column Thunderstorms Spotting DI approaching 70
Fire Behavior Prediction Models (eg BehavePlus)
INPUTS OUTPUTSFuel characteristics Rate of
SpreadFMC Fireline IntensitySlope Flame LengthsWind and morehellip
- Slide 9
- Slide 15
- Slide 46
-
Equilibrium Moisture Content For a given temperature and RH dead fuel
will reach a FMC at equilibrium Environmental conditions are not constant Fuel is constantly changes FMC to reach
EMC
The lag time to reach EMC depends on particle size
Timelag categories for dead woody fuels
Timelag Class Fuel Diameter
Timelag Range (hr)
1 Hour 0-14rdquo 0-2
10 Hour frac14rdquo-1rdquo 2-20
100 Hour 1-3rdquo 20-200
1000 Hour 3-8rdquo 200-2000
Timelag or ldquoresponse timerdquo is the time it takes for 63 of the change to occur between one EMC and a second EMC when a fuel in equilibrium with a stable environmental condition is suddenly exposed to a different stable environmental condition
Small diameter fuels react quickly to hourly and daily changes Important to monitor
Large diameter fuels react more to seasonal changes California versus Florida
Fine fuels drive fire behavior
Moisture of Extinction Dead 12-40 Live gt120
Available Fuel
Florida Fine Fuel Moisture Calculation Chart
httpwwwfl-dofcomwildfirerx_traininghtmlcbc
Live Fuels FMC can be much higher than dead
fuels (100-300) Influenced by Drought (KBDI) RH Wind
Ignition of live fuels may largely depend the combustion characteristics of other fuels (eg dead surface fuels)
Duff Moisture Very dry to very moist lt30 FMC duff can burn on its own Potential for tree mortality in
burning long unburned forests May smolder for long durations May cause lots of smoke
FMCWind
Increases O2 Bends flames Increases ROS Dries fuels
convectionwind
radiation
conduction
Slopes Similar effect as
wind Bends flames ROS higher
upslope
Slope Positiontop middle bottom
Aspect
Other topographic features Valleys Box Canyons Steep draws Elevation
ELEVATION
Indicators (on a Rx burn) KBDIgt500 FMC (fine) lt7 RHlt30 Cold front approaching Gusty winds Dust devilsfire whirls Just inland from seabreeze Well-defined convection column Thunderstorms Spotting DI approaching 70
Fire Behavior Prediction Models (eg BehavePlus)
INPUTS OUTPUTSFuel characteristics Rate of
SpreadFMC Fireline IntensitySlope Flame LengthsWind and morehellip
- Slide 9
- Slide 15
- Slide 46
-
Timelag categories for dead woody fuels
Timelag Class Fuel Diameter
Timelag Range (hr)
1 Hour 0-14rdquo 0-2
10 Hour frac14rdquo-1rdquo 2-20
100 Hour 1-3rdquo 20-200
1000 Hour 3-8rdquo 200-2000
Timelag or ldquoresponse timerdquo is the time it takes for 63 of the change to occur between one EMC and a second EMC when a fuel in equilibrium with a stable environmental condition is suddenly exposed to a different stable environmental condition
Small diameter fuels react quickly to hourly and daily changes Important to monitor
Large diameter fuels react more to seasonal changes California versus Florida
Fine fuels drive fire behavior
Moisture of Extinction Dead 12-40 Live gt120
Available Fuel
Florida Fine Fuel Moisture Calculation Chart
httpwwwfl-dofcomwildfirerx_traininghtmlcbc
Live Fuels FMC can be much higher than dead
fuels (100-300) Influenced by Drought (KBDI) RH Wind
Ignition of live fuels may largely depend the combustion characteristics of other fuels (eg dead surface fuels)
Duff Moisture Very dry to very moist lt30 FMC duff can burn on its own Potential for tree mortality in
burning long unburned forests May smolder for long durations May cause lots of smoke
FMCWind
Increases O2 Bends flames Increases ROS Dries fuels
convectionwind
radiation
conduction
Slopes Similar effect as
wind Bends flames ROS higher
upslope
Slope Positiontop middle bottom
Aspect
Other topographic features Valleys Box Canyons Steep draws Elevation
ELEVATION
Indicators (on a Rx burn) KBDIgt500 FMC (fine) lt7 RHlt30 Cold front approaching Gusty winds Dust devilsfire whirls Just inland from seabreeze Well-defined convection column Thunderstorms Spotting DI approaching 70
Fire Behavior Prediction Models (eg BehavePlus)
INPUTS OUTPUTSFuel characteristics Rate of
SpreadFMC Fireline IntensitySlope Flame LengthsWind and morehellip
- Slide 9
- Slide 15
- Slide 46
-
Small diameter fuels react quickly to hourly and daily changes Important to monitor
Large diameter fuels react more to seasonal changes California versus Florida
Fine fuels drive fire behavior
Moisture of Extinction Dead 12-40 Live gt120
Available Fuel
Florida Fine Fuel Moisture Calculation Chart
httpwwwfl-dofcomwildfirerx_traininghtmlcbc
Live Fuels FMC can be much higher than dead
fuels (100-300) Influenced by Drought (KBDI) RH Wind
Ignition of live fuels may largely depend the combustion characteristics of other fuels (eg dead surface fuels)
Duff Moisture Very dry to very moist lt30 FMC duff can burn on its own Potential for tree mortality in
burning long unburned forests May smolder for long durations May cause lots of smoke
FMCWind
Increases O2 Bends flames Increases ROS Dries fuels
convectionwind
radiation
conduction
Slopes Similar effect as
wind Bends flames ROS higher
upslope
Slope Positiontop middle bottom
Aspect
Other topographic features Valleys Box Canyons Steep draws Elevation
ELEVATION
Indicators (on a Rx burn) KBDIgt500 FMC (fine) lt7 RHlt30 Cold front approaching Gusty winds Dust devilsfire whirls Just inland from seabreeze Well-defined convection column Thunderstorms Spotting DI approaching 70
Fire Behavior Prediction Models (eg BehavePlus)
INPUTS OUTPUTSFuel characteristics Rate of
SpreadFMC Fireline IntensitySlope Flame LengthsWind and morehellip
- Slide 9
- Slide 15
- Slide 46
-
Moisture of Extinction Dead 12-40 Live gt120
Available Fuel
Florida Fine Fuel Moisture Calculation Chart
httpwwwfl-dofcomwildfirerx_traininghtmlcbc
Live Fuels FMC can be much higher than dead
fuels (100-300) Influenced by Drought (KBDI) RH Wind
Ignition of live fuels may largely depend the combustion characteristics of other fuels (eg dead surface fuels)
Duff Moisture Very dry to very moist lt30 FMC duff can burn on its own Potential for tree mortality in
burning long unburned forests May smolder for long durations May cause lots of smoke
FMCWind
Increases O2 Bends flames Increases ROS Dries fuels
convectionwind
radiation
conduction
Slopes Similar effect as
wind Bends flames ROS higher
upslope
Slope Positiontop middle bottom
Aspect
Other topographic features Valleys Box Canyons Steep draws Elevation
ELEVATION
Indicators (on a Rx burn) KBDIgt500 FMC (fine) lt7 RHlt30 Cold front approaching Gusty winds Dust devilsfire whirls Just inland from seabreeze Well-defined convection column Thunderstorms Spotting DI approaching 70
Fire Behavior Prediction Models (eg BehavePlus)
INPUTS OUTPUTSFuel characteristics Rate of
SpreadFMC Fireline IntensitySlope Flame LengthsWind and morehellip
- Slide 9
- Slide 15
- Slide 46
-
Florida Fine Fuel Moisture Calculation Chart
httpwwwfl-dofcomwildfirerx_traininghtmlcbc
Live Fuels FMC can be much higher than dead
fuels (100-300) Influenced by Drought (KBDI) RH Wind
Ignition of live fuels may largely depend the combustion characteristics of other fuels (eg dead surface fuels)
Duff Moisture Very dry to very moist lt30 FMC duff can burn on its own Potential for tree mortality in
burning long unburned forests May smolder for long durations May cause lots of smoke
FMCWind
Increases O2 Bends flames Increases ROS Dries fuels
convectionwind
radiation
conduction
Slopes Similar effect as
wind Bends flames ROS higher
upslope
Slope Positiontop middle bottom
Aspect
Other topographic features Valleys Box Canyons Steep draws Elevation
ELEVATION
Indicators (on a Rx burn) KBDIgt500 FMC (fine) lt7 RHlt30 Cold front approaching Gusty winds Dust devilsfire whirls Just inland from seabreeze Well-defined convection column Thunderstorms Spotting DI approaching 70
Fire Behavior Prediction Models (eg BehavePlus)
INPUTS OUTPUTSFuel characteristics Rate of
SpreadFMC Fireline IntensitySlope Flame LengthsWind and morehellip
- Slide 9
- Slide 15
- Slide 46
-
Live Fuels FMC can be much higher than dead
fuels (100-300) Influenced by Drought (KBDI) RH Wind
Ignition of live fuels may largely depend the combustion characteristics of other fuels (eg dead surface fuels)
Duff Moisture Very dry to very moist lt30 FMC duff can burn on its own Potential for tree mortality in
burning long unburned forests May smolder for long durations May cause lots of smoke
FMCWind
Increases O2 Bends flames Increases ROS Dries fuels
convectionwind
radiation
conduction
Slopes Similar effect as
wind Bends flames ROS higher
upslope
Slope Positiontop middle bottom
Aspect
Other topographic features Valleys Box Canyons Steep draws Elevation
ELEVATION
Indicators (on a Rx burn) KBDIgt500 FMC (fine) lt7 RHlt30 Cold front approaching Gusty winds Dust devilsfire whirls Just inland from seabreeze Well-defined convection column Thunderstorms Spotting DI approaching 70
Fire Behavior Prediction Models (eg BehavePlus)
INPUTS OUTPUTSFuel characteristics Rate of
SpreadFMC Fireline IntensitySlope Flame LengthsWind and morehellip
- Slide 9
- Slide 15
- Slide 46
-
Duff Moisture Very dry to very moist lt30 FMC duff can burn on its own Potential for tree mortality in
burning long unburned forests May smolder for long durations May cause lots of smoke
FMCWind
Increases O2 Bends flames Increases ROS Dries fuels
convectionwind
radiation
conduction
Slopes Similar effect as
wind Bends flames ROS higher
upslope
Slope Positiontop middle bottom
Aspect
Other topographic features Valleys Box Canyons Steep draws Elevation
ELEVATION
Indicators (on a Rx burn) KBDIgt500 FMC (fine) lt7 RHlt30 Cold front approaching Gusty winds Dust devilsfire whirls Just inland from seabreeze Well-defined convection column Thunderstorms Spotting DI approaching 70
Fire Behavior Prediction Models (eg BehavePlus)
INPUTS OUTPUTSFuel characteristics Rate of
SpreadFMC Fireline IntensitySlope Flame LengthsWind and morehellip
- Slide 9
- Slide 15
- Slide 46
-
FMCWind
Increases O2 Bends flames Increases ROS Dries fuels
convectionwind
radiation
conduction
Slopes Similar effect as
wind Bends flames ROS higher
upslope
Slope Positiontop middle bottom
Aspect
Other topographic features Valleys Box Canyons Steep draws Elevation
ELEVATION
Indicators (on a Rx burn) KBDIgt500 FMC (fine) lt7 RHlt30 Cold front approaching Gusty winds Dust devilsfire whirls Just inland from seabreeze Well-defined convection column Thunderstorms Spotting DI approaching 70
Fire Behavior Prediction Models (eg BehavePlus)
INPUTS OUTPUTSFuel characteristics Rate of
SpreadFMC Fireline IntensitySlope Flame LengthsWind and morehellip
- Slide 9
- Slide 15
- Slide 46
-
Slopes Similar effect as
wind Bends flames ROS higher
upslope
Slope Positiontop middle bottom
Aspect
Other topographic features Valleys Box Canyons Steep draws Elevation
ELEVATION
Indicators (on a Rx burn) KBDIgt500 FMC (fine) lt7 RHlt30 Cold front approaching Gusty winds Dust devilsfire whirls Just inland from seabreeze Well-defined convection column Thunderstorms Spotting DI approaching 70
Fire Behavior Prediction Models (eg BehavePlus)
INPUTS OUTPUTSFuel characteristics Rate of
SpreadFMC Fireline IntensitySlope Flame LengthsWind and morehellip
- Slide 9
- Slide 15
- Slide 46
-
Aspect
Other topographic features Valleys Box Canyons Steep draws Elevation
ELEVATION
Indicators (on a Rx burn) KBDIgt500 FMC (fine) lt7 RHlt30 Cold front approaching Gusty winds Dust devilsfire whirls Just inland from seabreeze Well-defined convection column Thunderstorms Spotting DI approaching 70
Fire Behavior Prediction Models (eg BehavePlus)
INPUTS OUTPUTSFuel characteristics Rate of
SpreadFMC Fireline IntensitySlope Flame LengthsWind and morehellip
- Slide 9
- Slide 15
- Slide 46
-
Other topographic features Valleys Box Canyons Steep draws Elevation
ELEVATION
Indicators (on a Rx burn) KBDIgt500 FMC (fine) lt7 RHlt30 Cold front approaching Gusty winds Dust devilsfire whirls Just inland from seabreeze Well-defined convection column Thunderstorms Spotting DI approaching 70
Fire Behavior Prediction Models (eg BehavePlus)
INPUTS OUTPUTSFuel characteristics Rate of
SpreadFMC Fireline IntensitySlope Flame LengthsWind and morehellip
- Slide 9
- Slide 15
- Slide 46
-
ELEVATION
Indicators (on a Rx burn) KBDIgt500 FMC (fine) lt7 RHlt30 Cold front approaching Gusty winds Dust devilsfire whirls Just inland from seabreeze Well-defined convection column Thunderstorms Spotting DI approaching 70
Fire Behavior Prediction Models (eg BehavePlus)
INPUTS OUTPUTSFuel characteristics Rate of
SpreadFMC Fireline IntensitySlope Flame LengthsWind and morehellip
- Slide 9
- Slide 15
- Slide 46
-
Indicators (on a Rx burn) KBDIgt500 FMC (fine) lt7 RHlt30 Cold front approaching Gusty winds Dust devilsfire whirls Just inland from seabreeze Well-defined convection column Thunderstorms Spotting DI approaching 70
Fire Behavior Prediction Models (eg BehavePlus)
INPUTS OUTPUTSFuel characteristics Rate of
SpreadFMC Fireline IntensitySlope Flame LengthsWind and morehellip
- Slide 9
- Slide 15
- Slide 46
-
Fire Behavior Prediction Models (eg BehavePlus)
INPUTS OUTPUTSFuel characteristics Rate of
SpreadFMC Fireline IntensitySlope Flame LengthsWind and morehellip
- Slide 9
- Slide 15
- Slide 46
-
- Slide 9
- Slide 15
- Slide 46
-