新托福阅读复习材料美国科学文摘精选.docx

新托福阅读复习材料美国科学文摘精选.docx

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新托福阅读复习材料美国科学文摘精选

新托福阅读复习材料：

美国科学文摘精选

ThePlanetEarth 

 The2000AntarcticOzoneHoleWasLargestEver 

 The2000AntarcticOzoneHolewasthelargesteverobserved.Earth'swetter

 upperatmospheremaydelayglobalozonerecovery.

 NASAresearchershavefoundthatanincreaseinwatervaporinthe

 stratosphere,stemmingpartiallyfromgreenhousegases,maydelayozone

 recoveryandincreasetherateofclimatechange.

 Tocheckonthelong-termstratosphericcoolingandozonedepletion,NASAput

 datafromsatellitesandotherremotesensorsintoitsGISSglobalclimate

 model.Itwasthefirststudytolinkgreenhousegasestoincreasedozone

 depletionoverpopulatedareas.

 Waterandozone.Climatemodelsshowcoolerstratospherictemperatureshappen

 whenthereismorewatervaporpresent.Watervaporalsoleadstothe

 breakdownofozonemolecules.

 Thestratosphereisthedrylayeroftheatmosphereabovethetroposphere,

 wheretemperaturesincreasewithheight.

 Accordingtosatellitedata,upperatmospherictemperaturesaroundtheworld-

 ataltitudesof20to35mileshigh--havecooledbetween5.4and10.8

 degreesFahrenheitoverrecentdecades.

 Drivingforces.NASAfoundtwodrivingforcesbehindthechangein

 stratosphericmoisture:

 Increasedemissionsofthegreenhousegasmethanearetransformedintowater 

 inthestratosphere,accountingforaboutathirdoftheobservedincrease 

 inmoisturethere. 

 Morewateristransportedfromtheloweratmosphere.Warmerairholdsmore 

 watervaporthancolderair,sotheamountofwatervaporinthelower 

 atmosphereincreasesasitiswarmedbythegreenhouseeffect.Greenhouse 

 gases,suchascarbondioxideandmethane,mayenhancethetransportof 

 waterintothestratosphere.

 Theincreasedtransportofwatervaportothestratosphereseemslikelyto

 havebeeninducedbyhumanactivities.

 Ozonedestruction.Risinggreenhousegasemissionsaccountforallorpartof

 thewatervaporincrease,whichcausesstratosphericozonedestruction.

 Whenmorewatervaporworksitswayintothestratosphere,thewatermolecules

 canbebrokendown,releasingreactivemoleculesthatcandestroyozone.If

 thetrendofincreasingstratosphericwatervaporcontinues,itcouldincrease

 futureglobalwarmingandimpedeozonestratosphericrecovery.

 Theimpactonglobalwarmingcomesaboutbecausebothwatervaporandozone

 aregreenhousegases,whichtrapheatleavingtheEarth.Whentheychange,the

 Earth'senergybalancechangestoo,alteringthesurfaceclimate.

 Warmerground.Increasedwatervaporinthestratospheremakesitwarmeron

 thegroundbytrappingheat,whiletheozonelossmakesitcolderonthe

 ground.

 Watervaporhasamuchlargereffect,sothatoverallthechangesincrease

 globalwarming.

 AlthoughozonedepletioncoolstheEarth'ssurface,repairingstratospheric

 ozoneisimportanttoblockharmfulultravioletradiation.Othergreenhouse

 gasemissionsalsoneedtobereduced.

 UARSsatellite.NASAcombinedsevenyearsofdatafromtheUpperAtmosphere

 ResearchSatellite（UARS）HalogenOccultationExperiment（HALOE）withdata

 collectedonthegroundtopaintacompletepictureoftheupperatmosphere.

 NASA'sHALOEwasaboardtheUARSspacecraftwhenitwaslaunchedSeptember12,

 1991aspartoftheEarthScienceEnterpriseProgram.Thespacecraft'smission

 atlaunchwastoimproveunderstandingofstratosphericozonedepletionby

 analyzingverticalprofilesofozone,hydrogenchloride,hydrogenfluoride,

 methane,watervapor,nitricoxide,nitrogendioxide,andaerosols.

 Fourteenyearsoflowerstratosphericmeasurementshaverevealedlarge

 increasesinwatervapor.Thoughsomeolderstudiesconflictwithlower

 stratosphericobservationsofwatervaportrends,newstudiesagreewiththe

 increases,showingtheyhavebeentakingplaceformorethanfourdecades. 

 WhatIsAnOzoneHole?

 Ozonemoleculesaremadeupofthreeatomsofoxygen.Theycompriseathin

 layeroftheatmospherethatabsorbsharmfulultravioletradiationfromthe

 Sun.

 Mostatmosphericozoneisfoundbetweenapproximatelysixmilesand18miles

 abovetheEarth'ssurface.

 Anozone"hole"iswhatscientistscallan"ozonedepletionarea"ofinthat

 regionofEarth'satmosphere.

 Reallybighole.Thelargest-everozoneholewasdetectedonSeptember6,

 2000,bytheTotalOzoneMappingSpectrometer（TOMS）aboardaNASAsatellite

 knownasEarthProbe（TOMS-EP）.

 TheAntarcticozoneholeisthreetimeslargerthantheentirelandmassof

 theUnitedStates,makingitthelargestsuchareaeverobserved.

 Theholehadexpandedtoarecordsizeof11millionsquaremiles.The