14-May-15 Physics 1 (Garcia) SJSU Chapter 14 Gasses & Plasmas.
Physics 003b. Seawater Physics Temperature Light Sound Buoyancy Dissolved gasses Waves Tides.
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Transcript of Physics 003b. Seawater Physics Temperature Light Sound Buoyancy Dissolved gasses Waves Tides.
Physics
003b
Seawater PhysicsSeawater Physics
• Temperature• Light• Sound• Buoyancy• Dissolved gasses• Waves• Tides
Temperature
IsothermsIsotherms
Lines of equal temperature
60o
30o
0o
30o
60o
polar
polar
temperate
tropic
temperate
Sea Surface TemperatureSea Surface Temperature
Oct. 2010
Sea Surface TemperatureSea Surface Temperature
Sea Surface TemperatureSea Surface Temperature
10-24-10 to 10-27-2010
Temperature Salinity DensityLow High Low High Low High
surface 0 m
200 m
1000 m
Thermocline + Halocline = Pycnocline
thermocline pycnoclinehalocline
Properties of Light in the Ocean
The Electromagnetic Radiation Spectrum
Only green and blue wavelengths pass through water a great distance.
Light Absorption in the Ocean
• Light Intensity–decreases with depth
–0-200 m (photic zone)
–200-1000m (dysphotic zone)
–>1000 (aphotic zone)
Light Penetration in the Ocean
~65% of visible light is absorbed in the 1st m
Photic Zone
Aphotic Zone
No Photosynthesis
200m
0 m
Wavelength (nm)400 700600500
Photosynthesis
Dysphotic Zone
1000m
Light effects organisms residing in the photic and aphotic zone.
• Phytoplankton productivity• Algae- green, brown, red• Predator/Prey relationships• Diurnal vertical migration• Bioluminescence- luminescent organs on
underside mimic downwelling light
Sound in Water
Speed of sound- faster in ocean (higher density)
1500 m/sec, which is 4x faster than in air
Difficult to determine direction of sound
Can hear many things such as ships miles away, shrimp eating, helicopters overhead, and whales communicating.
Sound in Water
source of noise
Dep
th (
m)
0
1000
2000
3000
4000
Speed of Sound (m/sec)
1,475 1,500
sofar layermin speed
high speed
high speed
Dep
th (
m)
0
500
1000
1500
2000
SOFAR Channel
Distance
SOFAR channel
sound rays
The depth at which the speed of sound is minimum; Thus, loud noises can be heard for thousands of km
Sound generated by Navy test in Indian Ocean at sofar layer was heard as far away as the Oregon coast. May affect behavior and anatomy of marine organisms
Sofar LayerSofar Layer
• Blubber
• Swim bladder
• Pneumatophore
Organisms adaptation to buoyancy in water
• Air chambers
• Large liver & heterocercal tail
• Buoyancy Compensator Device
(BCD)
Organisms adaptation to buoyancy in water
Dissolved Gasses in Seawater
Solubility of Gases in Seawater as a Function of Temperature (salinity @ 33o/oo)
Solubility(ml/l at atmospheric pressure)
Temperature N2 O2 CO2
(oC) .
0 14.47 8.14 8,700 10 11.59 6.42 8,030 20 9.65 5.26 7,350 30 8.26 4.41 6,660
Zebra ‘Tidepool’ Blenny
Air weighs 14 lbs/in2 (psi)
Absolute pressure is the combined pressure of water and air
Depth
0 ft
33 ft
66 ft
99 ft
Absolute Pressure
1 atm 14.7 psi
2 atm 29.4 psi
3 atm 44.1 psi
4 atm 58.8 psi
Relationship between water depth, pressure, and volume
Volume
x1
x 1/2
x 1/3
x 1/4
Boyle’s LawBoyle’s Law
For any gas at a constant temperature, the volume will vary inversely with absolute pressure while the density will vary with absolute pressure.
I.e., volume with pressure
pressure density
Henry’s LawHenry’s Law
When a mixture of gas is in contact w/a liquid, each gas will dissolve in the liquid in proportion to its partial pressure.
Gasses can go in and out of solution
e.g., open soda, get CO2 bubbles (CO2 is under pressure)
Dissolved gasses in seawater:Dissolved gasses in seawater:
Seawater AirN2 48% 78% O2 36% 21%CO2 15% 0.04%
Gasses dissolve most readily in cold water
Decompression sickness
It is caused when N2 enters the blood circulation and the tissues.
When extra N2 leaves the tissues, large bubbles form. N2 bubbles can travel throughout the system and into the lungs and blood routes.
Treatment: hyperbaric chamber
O2 Minimum Zone (OMZ)
O2 Content (ml/L)
Wat
er d
epth
(m
)
What causes the O2 minimum layer?
Marine snow
Why are there high levels of O2 at depth?
O2 Dead Zones
Surface currents are wind driven currents
Ekman Transport
Water flow in the Northern hemisphere- 90o to the right of the wind directionDepth is important
Upwelling and downwelling• Vertical movement of water ()
– Upwelling = movement of deep water to surface• Hoists cold, nutrient-rich water to surface• Produces high productivities and abundant marine life
– Downwelling = movement of surface water down• Moves warm, nutrient-depleted surface water down• Not associated with high productivities or abundant
marine life
upwelling
downwelling
Langmuir Circulation
1.Gravitational pull of the moon and sun
2.Centripetal force of the rotating Earth
Tides are generated by:
Tides are generated by:• the gravitational pull of the moon and sun
- moon has 2x greater gravitational pull than the sun - sun is 10 million x more massive than the
moon and is 390 times farther away
Centripetal force
CENTRIPETAL
GRAVITATIONAL FORCE
GRAVITATIONAL & CENTRIPETAL
• Diurnal Tide: 24 hr 50 min cycle
• Semi Diurnal Tide: 12 hr 25 min cycle
• Mixed Tide: 12 hr 25 min cycle
Tidal Cycles
• High water: a water level maximum ("high tide") • Low water: a water level minimum ("low tide") • Tidal range: the difference between high and low
tide• Spring Tide: full moon and new moon (14.77 days)• Neap Tide: 1st quarter and 3rd quarter (14.77 days)
Description of tides
Intertidal zoneHigh tide
Low tide
The monthly tidal cycle(29½ days)
• About every 7 days, Earth alternates between:– Spring tide
• Alignment of Earth-Moon-Sun system • Lunar and solar bulges constructively interfere• Large tidal range
– Neap tide• Earth-Moon-Sun system at right angles • Lunar and solar bulges destructively interfere• Small tidal range
Earth-Moon-Sun positions and the monthly tidal cycle
Spring TideHighest high tide and lowest low tide
Neap TideModerate tidal range
The Bay of Fundy: Site of the world’s largest tidal range
• Tidal energy is focused by shape and shallowness of bay
• Maximum spring tidal range in Minas Basin = 17 meters (56 feet)
Alma at High Tide
Alma at Low Tide
http://life.bio.sunysb.edu/marinebio/mbweb.html
Tidal Information
HAWAIIAN ISLANDSMean Spring Mean Tide Station Latitude Longitude Range Range Level Predictions SAND ISLAND, MIDWAY ISLANDS 28° 12.7' 177° 21.6' 0.8 1.2 0.6 Predictions
Laysan Island 25° 46' 171° 45' 0.7 1.0 0.4 Predictions East Island, French Frigate Shoals 23° 47' 166° 13' 0.9 1.4 0.6 Predictions Nonopapa, Niihau Island 21° 52' 160° 14' 1.0 1.6 0.7 Predictions
Kauai Island Waimea Bay 21° 57' 159° 40' 1.0 1.6 0.7 Predictions Port Allen, Hanapepe Bay 21° 54' 159° 35' 1.1 1.7 0.7 Predictions NAWILIWILI 21° 57.4' 159° 21.6' Predictions Hanamaulu Bay 22° 00' 159° 20' 0.0 1.2 1.8 Predictions Hanalei Bay 22° 13' 159° 30' 1.3 1.8 0.8 Predictions
Oahu Island Haleiwa, Waialua Bay 21° 36' 158° 07' - - 1.6 0.7 Predictions Waianae 21° 27' 158° 12' 1.2 1.8 0.8 Predictions
HONOLULU 21° 18' 157° 52' 1.3 2.0 0.8 Predictions Hanauma Bay 21° 17' 157° 42' 1.3 1.9 0.8 Predictions Waimanalo 21° 20' 157° 42' 1.1 1.8 0.8 Predictions MOKUOLOE 21° 26.2' 157° 47.6' 1.2 2.0 1.0 Predictions Waikane, Kaneohe Bay 21° 30' 157° 51' 1.4 2.2 1.1 Predictions
100m
dysphotic
aphotic
photic
Inquiry1. What zone does photosynthesis occur?2. Why does light appear to bend when it enters
water?3. Which wavelength of light penetrates the
ocean the deepest?4. What is SOFAR?5. It’s high tide at 9am with a diurnal tidal cycle.
When is the next high tide?6. What causes the OMZ?7. How do sharks maintain buoyancy?8. What areas in the ocean are the most
productive?9. Why is the open ocean considered a biological
desert?