Lecture 2 - University of Utahhome.chpc.utah.edu/~hallar/Thermo/Lectures/Lecture2.pdfLecture 2...
16
Lecture 2 • Atmospheric Composition : Chapter 1 • Water • Carbon Dioxide • Ozone • Thermodynamic System and Variables: Chapter2 • State vs. Process ATMOS 5130
Transcript of Lecture 2 - University of Utahhome.chpc.utah.edu/~hallar/Thermo/Lectures/Lecture2.pdfLecture 2...
Lecture2
• AtmosphericComposition:Chapter1• Water• CarbonDioxide• Ozone
• ThermodynamicSystemandVariables:Chapter2• Statevs.Process
ATMOS5130
1
10
100
1000
1e-05 0.0001 0.001 0.01 0.1 1 10 100
Z (
km
)
Fraction by volume (%)
Atmospheric composition vs. altitude
N2O2ArHe
ON
H
Fig.1.3
CompositionofaDRYAtmosphere:Troposphere
WaterVaporVaries0– 5%
Water• Despiteitsrelativelysmallfractionalcontribution,waterinallofitsphasesisbyfarthemostimportantconstituentfromameteorologicalpointofview.
• Centralroleinthethermodynamicsandenergybalanceoftheatmosphere,aswellasintheformationofclouds,rain,andsnow.
CLASSWILLFOCUSONBOTHDRYANDMOIST
THERMODYNAMICPROCESSES–
Wewillbespendingasignificantamountofourtimedescribing
thethermodynamicpropertiesofwaterintheatmosphere
Water
20% Rise in 50 Years
David Keeling
RiseinCarbonDioxide
310
320
330
340
350
360
370
380
390
1960 1970 1980 1990 2000 2010
Co
nce
ntr
atio
n [
pp
m]
Year
Carbon Dioxide Trend - Mauna Loa
Fig.1.4 PettyTextbookstates:383ppmin2007
409.44ppmonApril9,2016atMaunaLoa
HoustonCleanAirNetwork
OZONE=O3
AirParcelasthermodynamicsystem
a parcelof air
The atmosphere “TheSystem”
“TheEnvironment”
IsolatedSystem– exchangesneithermatternorenergywithenvironment
ClosedSystem– exchangesnomatter,butmanyexchangeenergyinvariousforms(timescales)
OpenSystem– exchangesbothmatterandenergywithenvironment
Wenormallyidealizeanairparcelasaclosedthermodynamicsystem
CHAPTER2:Statevs.ProcessVariables
StateVariablesUniquelydeterminedbythecurrentstateofthesystemPropertiesofasystemareatapointintime,nothowitarrivedatthatstate.
• Pressure• Temperature• Density
ProcessVariablesAssociatedwithaprocess,Exchangeofenergybetweensystemandenvironmente..g.heatenergy(Q)addedtoairsampletobringittocurrenttemp
HWproblem2.2
Indicatedwhichofthefollowingvariablescanbeviewedasstatevariables.
a) yourweightb) Thevolumeofgasolineburnedbyyourcaronthewayhomefromcollegec) Thevolumeofgasolineremaininginyourtankatanyparticulartimed) Thepositioninspaceofaweatherballoone) Distancetraveledbyweatherballoon
HWproblem2.2
Indicatedwhichofthefollowingvariablescanbeviewedasstatevariables.
a) yourweight=stateb) Thevolumeofgasolineburnedbyyourcaronthewayhomefromcollege=notstatec) Thevolumeofgasolineremaininginyourtankatanyparticulartime=stated) Thepositioninspaceofaweatherballoon=statee) Distancetraveledbyweatherballoon=notstate
Exactandinexactdifferentials
StateVariable:EXACT
ProcessVariable:Inexact
!𝑑𝑣 = 0�
�
! 𝛿𝑞 ≠ 0�
�
CHAPTER2:Extensivevs.IntensiveVariables
ExtensiveVariablesDependsonthesizeofthesampleorsysteme.g.volume
IntensiveVariablesDoesnotdependonthesizeofthesampleorsysteme.g.volumepermass
CONSERVEDVARIABLES
IMPORANTCHARACTERISTICOFANYSTATEVARIABLEISTHESETOFCONDITIONSUNDERWHICHITDOESORDOESNOTREMAINCONSTANT
Anisothermalprocessisoneinwhichtemperatureis heldconstantAnisobaricprocessisoneinwhichpressureisheldconstantAnisochoricprocessisoneinwhichvolumeisheldconstant.
