双语教学实例Meteorology市公开课金奖市赛课一等奖课件

MeteorologyGeographyDepartment

EastChinaNormalUniversity

ShuJiong第1页第1页TheEarth’sGlobalEnergyBalance

◆

Solarradiationisthedrivingpowersourceforwind,waves,weather,rivers,andoceancurrents.◆Theearth’senergybalance,whichincludeslandandoceansurfacesandtheatmosphere,controlstheseasonalanddailychangesintheearth’ssurfacetemperature.第2页第2页ElectromagneticRadiation

◆Wavelength

describesthedistanceseparatingonewavecrestfromthenextcrest.◆Theunittomeasurewavelengthisthe

micrometer.◆Radiantenergycanexistatanywavelength.第3页第3页RadiationandTemperature

◆

Thereisaninverserelationshipbetweentheradiationthatanobjectemitsandthetemperatureoftheobject.

◆Hotobjectsradiatemoreenergy,andatshorterwavelengths,thancoolerobjects.第4页第4页Solarradiation

◆TheSunisaballofconstantlychurninggasesthatareheatedbycontinuousnuclearreactions.Ithasasurfacetemperatureofabout6000oC.Likeallobjects,itemitsenergyintheformofelectromagneticradiation.第5页第5页electromagneticspectrum

Shortwaveradiation

◆Ultravioletradiation

(0.2to0.4μm)

◆Visiblelight

radiation(0.4to0.7μm)◆Shortwaveinfraredradiation

(0.7to3μm)

Longwaveradiation

◆Thermalinfraredwavelengths

(>3μm)

第6页第6页Characteristicsofsolarenergy

◆

Thesundoesnotemitallwavelengthsofradiationequally◆

Theintensityofsolarenergyisstrongestinvisiblewavelengths第7页第7页LongwaveradiationfromtheEarth

◆

Theearth’ssurfaceandatmospherearemuchcolderthanthesun’ssurface,sotheenergyfromtheEarthhaslongerwavelength

第8页第8页Theglobalradiationbalance

◆Theearthconstantlyabsorbssolarshortwaveradiationandemitslongwaveradiation.◆Thesunprovidesanearlyconstantflowofshortwaveradiationtowardearth.◆Theatmosphere,land,andoceanalsoemitenergyintheformoflongwaveradiation.第9页第9页Figure1GlobalEnergyBalance第10页第10页InsolationovertheGlobe

◆Insolation(incomingsolarradiation)dependsontheangleofthesunabovethehorizon.第11页第11页ThePathoftheSunintheSky

Thesun’spathintheskychangesgreatlyinpositionandheightabovehorizonfromsummertowinter.◆Atequinox,thesunrisesdirectlytotheeastandsetsdirectlytothewest.◆Thenoonsunispositionedatanangleof50oabovethehorizoninthesouthernsky.

第12页第12页◆Thesunisabovethehorizonforexactly12hours.◆Atnoonitwillbe73.5oabovethehorizon.◆Thesunisabovethehorizonforabout15hour第13页第13页

DailyInsolationThroughtheYear

◆

Dailyinsolationdependsontwofactors:◆

theangleatwhichthesun’sraysstriketheearth◆

thelengthoftimeofexposuretotherays◆

theequatorhastwoperiodsofmaximumdailyinsolation,theseperiodsoccurneartheequinoxes.第14页第14页◆Therearealsotwominimumperiodsnearthesolstices,whenthesubsolarpointmovesfarthestnorthandsouthfromtheequator.Alllatitudesbetweenthetropicofcancer23.5oNandthetropicofCapricorn23.5oShavetwomaximumandminimumvalues.◆Seasonalpatternofdailyinsolationisdirectlyrelatedtolatitude.第15页第15页AnnualInsolationbyLatitude

◆Annualinsolationvariessmoothlyfromtheequatortothepole◆Theannualinsolationvalueatthepoleisabout40%ofthevalueattheequator.◆Thetiltingoftheearth’saxisredistributesasignificantportionoftheearth’sinsolationfromtheequatorialregionstowardthepoles.第16页第16页WorldLatitudeZones

◆Theequatorialzoneencompassestheequatorandcoversthelatitudebeltroughly10oNto10oS◆SpanningthetropicsofcancerandCapricornarethe

tropicalzones,rangingfromlatitudes10oto25onorthandsouth第17页第17页◆Movingtowardthepolesfromeachofthetropicalzonesaretransitionalregionscalledthesubtropicalzones,rangingfromlatitudes25oto35onorthandsouth◆Themidlatitudezonesliebetween35oand55olatitudesinthenorthernandsouthernhemispheres第18页第18页◆Borderingthemidlatitudezonesonthepolewardsidearethesubarcticzoneand

subantarcticzone,55oto60onorthandsouthlatitudes◆AstridethearcticandAntarcticcirclesfromlatitudes60oto75oNandSliethe

arcticandAntarcticzones◆Thepolarzones,northandsouth,arecircularareasbetweenabout75olatitudeandthepoles第19页第19页CompositionoftheAtmosphere

◆

Theearth’satmosphereconsistsofair-amixtureofvariousgasessurroundingtheearthtoaheightofmanykilometers.

◆Almostalltheatmosphere97%lieswithin30kmoftheearth’ssurface.

第20页第20页

Theupperlimitoftheatmosphereisataheightofapproximately10,000kmabovetheearth’ssurface,adistanceapproachingthediameteroftheearthitself.第21页第21页◆Pure,dryairconsistslargelyofnitrogen,about78%byvolume,andoxygen,about21%.Othergasesaccountfortheremaining1%◆Watervaporisanimportantcomponentoftheatmospherethatvariesinconcentrationfromplacetoplaceandtimetotime第22页第22页OzoneintheUpperAtmosphere

◆Ozone(O3)isfoundmostlyintheupperpartoftheatmosphere,inalayertermedthestratosphere.Ozoneinthestratosphereabsorbsultravioletradiationfromthesunasthisradiationpassesthroughtheatmosphere

第23页第23页Atbothpolarregions,climateandchemistrycombinetodepleteozoneduringspringmonths.Darkblueindicateslowestozoneamounts.ArctictotalozoneamountsseenbyTOMSinMarch(above,left)wereamongthelowesteverobservedinthenorthernhemisphere.TheAntarcticozoneholeof(above,right)wasthesecondlargesteverobserved.第24页第24页SensibleHeatandLatentHeatTransfer

◆SensibleHeat-thequantityofheatheldbyanobjectthatcanbesensedbytouchingorfeeling◆Whentwoobjectsofunliketemperaturecontacteachother,heatenergymovesbyconductionfromthewarmertothecooler.Thistypeofheatflowisreferredtoassensibleheattransfer第25页第25页TheGlobalEnergySystem

◆

InsolationlossesintheAtmosphere◆Albedo◆CounterradiationandtheGreenhouseEffect◆GlobalEnergyBudgetoftheAtmosphereandSurface◆NetRadiation,Latitude,andtheEnergyBalance第26页第26页WindsandthePressureGradientForce

◆Windisairmotionwithrespecttotheearth’ssurface,anditisdominantlyhorizontal.◆

Barometricpressurefallswithincreasingaltitudeabovetheearth’ssurface.第27页第27页◆

Thechangeinbarometricpressureacrossthehorizontalsurfaceofamapconstitutesapressuregradient.

Thegradientisinthedirectionfromhigherpressuretolowerpressure.第28页第28页◆

Whereapressuregradientexists,airmoleculestendtodriftinthesamedirectionasthatgradient.Thistendencyformassmovementoftheairisreferredtoasthepressuregradientforce.第29页第29页SeaandLandBreezes

◆

Duringthedaytime,morerapidheatingofthelowerairlayeroverthelandthanovertheoceancausesapressuregradientfromseatoland.Airmovinglandwardinresponsetothisgradientfromhighertolowerpressureconstitutestheseabreeze.

第30页第30页Athigherlevels,areverseflowsetsin.Togetherwithweakrisingandsinkingairmotions,acompleteflowcircuitisformed.第31页第31页◆

Duringthenight,whenradiationalcoolingofthelandisrapid,thelowerairbecomescolderoverthelandthanoverthewater.Higherpressurenowdevelopsoverlandandthebarometricgradientisreversed.Airnowmovesfromlandtoseaasa

landbreeze.第32页第32页Figure2Seabreezeandlandbreeze第33页第33页CyclonesandAnticyclones

◆Acenteroflowpressureiscalledacyclone;acenterofhighpressureisananticyclone.◆Windsinacycloneinthenorthernhemisphereshowananticlockwiseinspiral.Inananticyclone,thereisaclockwiseoutspiral.第34页第34页◆Thesurfacewindsspiralinwardonthecenterofthecyclone,sotheairisconvergingonthecenterandmustalsorisetobedisposedofathigherlevels.第35页第35页◆Fortheanticyclone,bycontrast,surfacewindsspiraloutfromthecenter.Thismotionrepresentsadivergingofairflowandmustbeaccompaniedbyasinkingofairinthecenteroftheanticyclonetoreplacetheoutmovingair.第36页第36页Figure3Surfacewindsincyclonesandanticyclones第37页第37页

GlobalDistributionofSurfacePressureSystems

◆Overtheequatorialzoneisabeltofsomewhatlowerthannormalpressure,between1011and1008mb,whichisknownastheequatorialtrough.第38页第38页◆Lowerpressureisconspicuousbycontrastwithbeltsofhigherpressurelyingtothenorthandsouthandcenteredataboutlat.30°NandS.Thesearethe

subtropicalbeltsofhighpressure,inwhichpressureexceed1020mb.

第39页第39页◆Inthesouthernhemisphere,southofthesubtropicalhigh-pressurebelt,isabroadbeltoflowpressure,extendingfromthemidlatitudezonetothearcticzone.Theaxisoflowpressureiscenteredataboutlat.65S.Thispressuretroughiscalledthe

subantacticlow-pressurebelt.第40页第40页◆LyingoverthecontinuousexpanseofSouthernOcean,thistroughhasaveragepressureaslowas984mb.OverthecontinentofAntarcticaisapermanentcenterofhighpressureknownasthe

polarhigh.第41页第41页

TheGlobalPatternofSurfaceWinds

◆Fromthetwosubtropicalhigh-pressurebeltsthepressuregradientisequatorward,leadingdowntotheequatorialtroughoflowpressure.AirmovingfromhightolowpressureisdeflectedbytheCorioliseffect.Asaresult,twobeltsof

tradewinds

areproduced.第42页第42页◆Meetingofthetradestakesplacewithinanarrowzonecalledthe

intertropicalconvergencezone.◆Alongpartsoftheequatorialtroughoflowpressureatcertaintimesofyear,thetradesdonotcometogetherinconvergence.Instead,abeltofcalmsandvariblewinds,calledthedoldrums,forms.第43页第43页◆Betweenlat.35and60NandSisthebeltofprevailingwesterlywinds,orwesterlies.◆Awindsystemcalledthepolareasterliesischaracteristicofthearcticandpolarzones.第44页第44页Figure4Surfacewinds第45页第45页

MonsoonWindsof

SoutheastAsia

◆InsummersouthernAsiadevelopsacycloneintowhichthereisstrongflowofair.FromtheIndianOceanandthesouthwesternPacific,warm,humidairmovesnorthwardandnorthwestwardintoAsia.ThisairflowconstitutesthesummermonsoonandisaccompaniedbyheavyrainfallinsoutheasternAsia.第46页第46页◆Inwinter,Asiaisdominatedbyastrongcenterofhighpressurefromwhichthereisanoutwardflowofairreversingthatofthesummermonsoon.Blowingsouthwardandsoutheastwardtowardtheequatorialoceans,thisairflowconstitutesthewintermonsoonandbringsdryweatherforaperiodofseveralmonths.第47页第47页

Mountainwindsand

valleywinds

◆Duringthedaylighthourstheairalongtheslopesofthemountainsisheatedmoreintenselythantheairatthesameelevationoverthevalleyfloor.Thiswarmairglidesupalongtheslopeandgeneratesa

valleywind.第48页第48页◆Aftersunsetthepatternisreversed.Rapidradiationheatlossalongthemountainslopesresultsincoolairdrainageintothevalleybelowandcausesthemountainwind.

第49页第49页GlobalCirculation

◆TheHadleyCellCirculation

Inthezonebetweentheequatorandroughly30°latitude,thesurfaceflowisequatorwardwhiletheflowaloftispoleward.Neartheequatorthewarmrisingairthatreleaseslatentheatduringtheformationofcumulustowersisbelievedtoprovidetheenergytodrivethiscell

第50页第50页◆Thecirculationbetween30and60latitudeisjustoppositethatoftheHadleycell.Thenetsurfaceflowispoleward,andbecauseoftheCorioliseffect,thewindshaveastrongwesterlycomponent.第51页第51页◆Aboutthecirculationinthehighlatitudes,itisgenerallybelievedthatsubsidencenearthepolesproducesasurfaceflowthatmovesequatorwardandisdeflectedintothepolareasterliesofbothhemisphere.Theregionwherethecoldpolarwindsandthewarmerwesterlyflowofthemidlatitudesclashhasbeennamedthepolarfront.第52页第52页TheglobalCirculationandMan’sEnvironment

◆Inlowlatitudes,theHadleycelloperateslikeasimpleheatenginetotransportheatfromtheequatorialzonetothesubtropicalzone.第53页第53页◆Upper-airwavestakeupthetransportandmovewarmairpolewardinexchangeforcoldair.◆Theglobalatmosphericcirculationalsotransportsheatinthelatentformheldbywatervapor.

第54页第54页◆Windscarryalargeamountofwatervapor,whichisdepositedasprecipitationonthecoast.◆Windsalsotransportatmosphericpollutants,carryingthemtensandhundredsofkilometersfromthesourcesofpollution.第55页第55页

Airtemperature

◆

Temperature

isameasureofthelevelofsensibleheatofmatter,whetheritisgaseous,liquid,orsolid.◆

Conduction

describestheflowofheatfromawarmersubstancetoacolderonewhenthetwoaretouching.第56页第56页◆

Evaporation,theprocessbywhichwaterchangesfromaliquidtoagasbyabsorbingheat,tendstolowerthetemperatureofawetsurface.第57页第57页MeasurementofairtemperatureAirtemperaturesarenowautomaticallyrecordedbythermometersatauniformheightabovetheground.第58页第58页Thedailycycleofairtemperature◆Becausetheearthrotatesonitsaxis,incomingsolarenergyatalocationcanvarywidelythroughoutthe24-hourperiod.◆Insolationisgreatestinthemiddleofthedaylightperiod,whenthesunisatitshighestpositioninthesky,andfallstozeroatnight.第59页第59页Dailyinsolationandnetradiation◆Thedailycycleoftemperatureiscontrolledbythedailycycleofnetradiation.◆Attheequinox,insolationbeginsataboutsunrise(6a.m.),risestoapeakvalueatnoon,anddeclinestozeroatsunset(6p.m.).第60页第60页◆AttheJunesolstice,insolationbeginsabouttwohoursearlier(4a.m.)andendsabouttwohourslater(8p.m.).◆AttheDecembersolstice,insolationbeginsabouttwohourslaterthantheequinoxcurve(8a.m.)andendsabouttwohoursearlier(4p.m.).第61页第61页◆Whennetradiationispositive,thesurfacegainsheat,andwhennegative,itlosesheat.◆Netradiationbeginsthe24-hourdayasanegativevalue-adeficit-atmidnight.Thedeficitcontinuesintotheearlymorninghours.Netradiationshowsapositivevalue-asurplus-shortlyaftersunriseandrisessharplytoapeakatnoon.第62页第62页

Dailytemperature

Theminimumdailytemperatureusuallyoccursaboutahalfhouraftersunrise.Airtemperaturerisessharplyinthemorninghoursandcontinuestoriselongafterthenoonpeakofnetradiation.Airtemperaturerisesaslongasnetradiationispositive.Temperaturesarelowestjustaftersunriseandhighestinmidafternoon.第63页第63页Urbanandruraltemperaturecontrasts◆Urbansurfaceslackmoistureandsoarewarmerthanruralsurfacesduringtheday.Atnight,urbanmaterialsconductstoredheattothesurface,alsokeepingtemperatureswarmer.第64页第64页

Theurbanheatisland

◆Asaresultoftheaboveeffects,airtemperaturesinthecentralregionofacityaretypicallyseveraldegreeswarmerthanthoseofthesurroundingsuburbsandcountryside.Thisiscalledaheatisland.第65页第65页◆Theheatislandpersiststhroughthenightbecauseoftheavailabilityofaheatstoredinthegroundduringthedaytimehours.◆Anotherimportantfactorinwarmingthecityisfuelconsumption.Insummer,citytemperaturesareraisedthroughtheuseofairconditioning.第66页第66页

TemperaturestructureoftheAtmosphere

Troposphere

◆Thetroposphereisthelowestatmosphericlayer,inwhichtemperaturedecreaseswithincreasingelevation.Everydayweatherphenomena,suchascloudsorstorms,occurmainlyinthislayer.第67页第67页◆Thetropospherecontainssignificantamountsofwatervaporandcountlesstinydustparticles.

第68页第68页Stratosphere◆Abovethetroposphereliesthestratosphereinwhichtheairbecomesslightlywarmerasaltitudeincreases.◆Thestratosphereextendstoaheightofroughly50kmabovetheearth’ssurface.第69页第69页◆Itisthehomeofstrong,persistentwindsthatblowfromwesttoeast.◆Oneimportantfeatureofthestratosphereisthatitcontainstheozonelayer.第70页第70页

High-MountainEnvironments

◆Athighelevations,airtemperaturesaregenerallycoolerandshowagreaterday-to-nightrange.第71页第71页

TemperatureInversionandFrost

◆Inatemperatureinversion,airtemperatureincreaseswithaltitude.◆Low-leveltemperatureinversionsoftenoccuroversnow-coveredsurfacesinwinter.

第72页第72页◆Inversionscanalsoresultwhenawarmairlayeroverliesacolderone.Thistypeofinversionisoftenfoundalongthewestcoastsofmajorcontinents.第73页第73页Frost◆Ifthetemperatureofthelowermostairfallsbelowthefreezingpoint,forsensitiveplantsduringthegrowingseason,thistemperatureconditioniscalledakillingfrost.第74页第74页

Theannualcycleofairtemperature

Theannualcycleofnetradiation,whichresultsfromthevariationofinsolationwiththeseasons,drivestheannualcycleofairtemperatures.第75页第75页

Landandwatercontrasts

◆Land-watercontrastskeepairtemperaturesatcoastallocationsmoreconstantthanatinteriorcontinentallocations.◆Oceansheatandcoolmoreslowlythancontinents.第76页第76页◆Thesurfaceofanyextensive,deepbodyofwaterheatsmoreslowlyandcoolsmoreslowlythanthesurfaceofalargebodyoflandwhenbotharesubjectedtothesameintensityofinsolation.第77页第77页

Dailytemperaturecycle

P62Figure3.15第78页第78页Theaveragedailycycleofairtemperatureforfourdifferentmonthsshowstheeffectofcontinentalandmaritimelocation.DailyandseasonalrangesaregreatatElPaso,astationinthecontinentalinterior,butonlyweaklydevelopedatNorthHead,Washington,whichisonthePacificcoast.TheseasonaleffectonoveralltemperaturesisstrongeratElPaso.第79页第79页

Annualtemperaturecycle

P63figure3.16Annualcyclesofinsolation(a)andmonthlymeanairtemperature(b)fortwostationsatlat.50°N:Winnipeg,Canada,andScillyIslands,England.第80页第80页Insolationisidenticalforthetwostations.Winnipegtemperaturesclearlyshowthelargeannualrangeandearliermaximumandminimumthatarecharacteristicofitscontinentallocation.ScillyIslandstemperaturesshowitsmaritimelocationinthesmallannualrangeanddelayed