atmos 5130 physical meteorology ii...
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ATMOS5130PhysicalMeteorologyIIThermodynamics
Dr.GannetHallarUniversityofUtah
SpringSemester2016(1.5credits)Monday,Wednesday,Friday
10:45– 11:35amWBB- Rm.820
January9toFebruary27,2017
CourseWebsite• Lecturespresentedinclass• Classroomnotes• StudyGuides
http://chpc.utah.edu/~hallar/Thermo/
CourseTextbookAFirstCourseinAtmosphericThermodynamics
byGrantW.Petty
Listpricewhenpurchasedthroughbookstores:$51.DiscountedpricewhenordereddirectlyfromSundogPublishing:$36,includingfreeshippingtoU.S.addresses.http://www.sundogpublishing.com/
BringCalculatortoClassYouwillbeexpectedtosolveproblemsinclass
ClassroomPolicies• StudentsmusttakeeveryexamandquizwithexceptionsgovernedbyUniversityPolicy.• Plagiarizing,copying,cheating,orotherwisemisrepresentingone’sworkwillnotbetolerated.• Missingclasswillnotbepenalizeddirectly,butusuallyresultsinpoorproblemsetandexamperformance.• Stronglysuggestcompletingreadingassignments.• Homeworkisdueatthestartofclassontheduedate,unlessotherwisenoted.• Latehomeworkwillnotbeaccepted.• Pleaserespectothersrighttolearn.
Lecture1:Chapter1• IntroductiontoAtmosphericThermodynamics• Pressure• Temperature
Meteorology3510
WhatisThermodynamics?
• Studyofheattoworktransformations(andthereverse)
©1998TheMcGraw-HillCompanies
Nowweapplythattotheatmosphereinrelationtoweatherandclimate
WhatisAtmosphericThermodynamics?Describesthephysicalbehaviorofaironlocalscale
Howdoesanisolated“parcel”ofairrespondtochangesintemperatureandpressure?
Howdothesechangesaffectitsbehaviorinrelationshiptothesurroundingatmosphere?
a parcelof air
The atmosphere
Pressure
• https://www.youtube.com/watch?v=QeAp3CuGjk8
e.g.ThermodynamicDiagram=Skew-Tlogpchart
IntroductiontoHydrostaticBalance
• Pressureatanypointintheatmosphereequalstheweightperunitareaabovethatpoint.• Pressure=Forceperunitarea• Weightofanobject=Force=Fg =mg• g=accelerationduetogravity(9.81ms-2)atsealevel
AckermanandKnox,2012
Pa=Newton/m2
100Pa=hPa =mbar
WorkismeasuredinJoules(J)=Newton*m
Thus,pressurehasunitsofJ/m3
Energydensity
Physicalgeography.net
Temperature/Heat
Temperatureisthequantitythatdeterminesthedirectioninwhichthermalenergy(“heat”)willflowwhentwoobjectsarebroughtintocontactwithoneanother.
Temperatureofasubstanceisproportionaltotheaveragekineticenergyofitsmolecules.
AbsoluteTemperatureTranslational Kinetic Energy
TemperatureScales
TemperatureScales
Whatdoesthismean?
TemperatureScales
Whatdoesthismean?
NearlyallmolecularmotionceasesandΔS=0foranyadiabaticprocess,whereSistheentropy.
NASA
EnvironmentalLapseRate
TypicallypositiveintheTroposphere
WhenNegative=Inversion
StandardLapseRate=6.5C/km
-40 -30 -20 -10 0 10 20 30 40Temperature [oC]
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Tropopause (15.9 km)
Inversions
Stratosphere
Troposphere
Inversion
Dodge City, Kansas 2004 09 08 12Z
6.5 o per km
Pre
ssu
re [h
Pa
]
Fig.1.5
Inversions
JudeTibway tookthisphotooftheSaltLakeValleyfromnearSnowbirdinFebruary2010
12Z 25 Aug 2005 Green Bay, WI
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-40 -30 -20 -10 0 10 20Temperature [oC]
Pre
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a)
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-40 -30 -20 -10 0 10 20 30 40
-40-50-60-70-80-90-100-110-120
Temperature [oC]
Pre
ssu
re (
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a)
Skew T - log pb) 12Z 25 Aug 2005 Green Bay, WI
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-40 -30 -20 -10 0 10 20Temperature [oC]
Pre
ssure
(hP
a)
-60 -50
T - log pa)
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-40 -30 -20 -10 0 10 20 30 40
-40-50-60-70-80-90-100-110-120
Temperature [oC]
Pre
ssure
(hP
a)
Skew T - log pb)
Fig.1.19
Atmosphericthermodynamicprinciplesformfoundationof:• atmosphericdynamics(thestudyofthefluidmotionsoftheatmosphere)
• cloudandprecipitationphysics• weatherforecasting(especiallytheforecastingofsevereweather)
Astheairtravelstowardconvectivesystem,itgainsmoisture.Ascendingmotioninadeepconvectivecoreproducesairexpansion,cooling,andcondensation.Upperleveloutflowvisibleasananvilcloudiseventuallydescending.
(ImageprovidedbyRobertSimmon)
(ImageprovidedbyUKMetOffice)