气象科技英语翻译.docx

气象科技英语翻译.docx

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气象科技英语翻译

气象科技英语翻译

Likeafishintheocean,manisconfinedtoaveryshallowlayerofatmosphere.ThegaseousenvelopeoftheEarthisphysicallyinhomogeneousinboththeverticalandhorizontaldirections,althoughthehorizontalinhomogeneityismuchlessmarkedthantheverticalinhomogeneity.

Variouscriteriahavebeendevisedfordividingtheatmosphereintolayers.Thisdivisioncanbebasedonthenatureoftheverticaltemperatureprofile,onthegaseouscompositionoftheairatdifferentaltitudes,andtheeffectoftheatmosphereonaircraftatdifferentaltitudes,etc.Thedivisionbasedonthevariationoftheairtemperaturewithaltitudeisusedmostcommonlyinthemeteorologicalliterature.

AccordingtoapublicationoftheagrologicalcommissionoftheWorldMeteorologicalOrganization（WMO）in1961,theEarth’satmosphere,isdividedintofivemainlayers:

thetroposphere,thestratosphere,themesosphere,thethermosphereandtheexosphere.Theselayersareboundedbyfourthintransitionregions:

thetropospause,thestratospause,themesospause,thethermospause.

ThetroposphereisthelowerlayeroftheatmospherebetweentheEarth’ssurfaceandthetropopause.Thetemperaturedropswithincreasingheightinthetroposphere,atameanrateof6.5℃perkilometer（lapserate）.Theupperboundaryofthetroposphereliesataheightofapproximately8to12kminthepolarandtropospherecontainsabout75%ofthetotalmassofatmosphericair,whileinthetropicsitcontainsabout90%.Thetropoauseisanintermediatelayerinwhicheitheratemperatureinversionoranisothermaltemperaturedistributionisobserved.

Thestratosphereistheatmosphericlayerabovethetroposphere.Inthestratospherethetemperatureeitherincreaseswithheightorremainsnearlyconstant.Inthelowerpartofthestratosphere（uptoapproximately20kmabovetheEarth’ssurface）thetemperatureispracticallyconstant（about－56℃）.Whilefurtherupthetemperatureincreaseswithaltitudeatarateofabout1℃/kmatheightsof20to30kmandabout2.8℃/kmataltitudesfrom32to47km.Underthestandardconditionsthetemperatureatthe47kmlevelisnormally-2.5℃.

ThisincreaseintemperaturewithheightisduetotheabsorptionofUVsolarradiationbyozonemolecules.Itshouldbenotedthatabout99%ofthetotalmassofatmosphericairisconcentratedinthetroposphereandstratosphere,whichextenduptoanlatitudeof30or35km.Thestratopauseisanintermediatelayerbetweenthestratosphereandthemesosphere（inthealtituderegionfrom47to52km）,inwhichthetemperatureremainsconstantatabout0℃.

Thethermosphereistheatmosphericlayerabovethemesopause.Thetemperatureinthislayerincreaseswithincreasingaltitude,reachingabout2000℃atabout450km,themeanheightoftheupperboundaryofthethermosphere.ThetemperatureincreaseinthislayerismainlycausedbytheabsorptionofUVsolarradiationbyoxygenmolecules,whichdissociateasaresultofthis.

Theexosphereisthefurthestoutandtheleaststudiedpartoftheupperatmosphere.Itislocatedabove450kmaltitude.Theairdensityintheexosphereissolowthatatomsandmoleculescanescapefromitintointerplanetaryspace.

Finally,alongwiththeabovedivisionoftheatmosphere,wewillalsomakeuseofadivisionbasedontheextentofatmosphericinteractionwiththeEarth’ssurface.Accordingtothisprincipe,theatmosphereisusuallydividedintoasocalledboundarylayer（sometimesalsocalledthefrictionlayer）andthefreeatmosphere.Theatmosphericboundarylayer（upto1or1.5km）isinfluencedconsiderablybytheEarth’ssurfaceandbyeddy-viscosityforces.Atthesametime,wecanneglect,asafirstapproximation,theinfluenceofeddy-viscosityforcesinthefreeatmosphere.

Ofalltheaboveatmosphericlayers,onlythetroposphere（especiallyitsboundarylayer）ischaracterizedbyamarkedinstabilityoftheverticaldistributionofthemeteorologicalparameters.Itisinthislayerthatbothtemperatureinversionsandsuperadiabatictemperaturevariationswithheightareobserved.

TheEarth’satmosphereisamixtureofgasesandaerosols,thelatterbeingthenamegiventoasystemcomprisedofsmallliquidandsolidparticlesdistributedintheair.

Airisnotaspecificgas:

rather,itisamixtureofmanygases.Someofthem,suchasnitrogen,oxygen,argon,neon,andsoon,mayberegardedaspermanentatmosphericcomponentsthatremaininfixedproportionstothetotalgasvolume.Otherconstituentssuchaswatervapor,carbondioxide,andozonevaryinquantityfromplacetoplaceandformtimetotime.

Theprincipalsourcesofnitrogen,themostabundantconstituentofair,aredecayingfromagriculturaldebris,animalmatter,andvolcaniceruption.Ontheothersideoftheledger,nitrogenisremovedfromtheatmospherebybiologicalprocess