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2022年英語六級考試沖刺練習(xí)：閱讀篇45Rainmaking

Theideaofrainmakingisalmostasoldasman,butitwasnotuntil1946thatmansucceededinmakingrain.Inancienttimes,rainmakershadclaimedtobringrainbymanymethods:dancing,singing,killingvariouskindsoflivingcreatures(includinghumans),andblowingastreamofwaterintotheairfromakindofpipe.

Morerecently,somerainmakersclaimedtomakerainbyshootingguns,causingexplosions,orburningchemicals,thesmokeofwhichwassupposedtocauseraintofall.Theserainmakersaskedforasmuchas1,000dollarstomakeaninchofrain.Onewassoeffectivethathewasalmosthanged.Hewasbelievedtohavecausedatwenty-inchraininsouthernCaliforniathatfloodedtheland,killedseveralpeople,anddidmillionsofdollars”worthofdamage.

Before1946,rainmakerswereeitherliarsorhonestpeoplewhohappenedtohavegoodluck.ScientificrainmakingwasstartedinthatyearbyVincentJ.Schaefer,ascientistatthelaboratoriesoftheGeneralElectricCompanyinNewYorkState.Hissuccesswastheresultofaluckyaccidentthatchangedyearsoffailureintovictory.

Foralongtime,menhaveunderstoodwhereraincomesfrom.Waterfromthesurfaceofoceansandlakesbecomespartoftheair,whereitformscloudsfromwhichrainfalls.Butexactlywhatstartstheformationofraindropswasnotknownuntilquiterecently.AmannamedJohnAitkenprovedthatdropsofwatergatheraroundtinybitsofdustorothermatter.Thecentersofthedropsaresosmallthatthehumaneyecannotseethem.Withoutsuchcenters,itseems,raindropsdonotform.

DuringWorldWarII,Dr.IrvingLangmuir,ascientist,washiredbytheGeneralElectricCompanytostudyhowandwhyiceformsonthewingsofairplanes.HeandayoungassistantnamedSchaeferwenttoamountaininthestateofNewHampshire,wheresnowstormsarecommonandcoldwindsblow.

WhileinNewHampshire,LangmuirandSchaeferweresurprisedtolearnthatoftenthetemperatureofthecloudssurroundingthemwasfarbelowthefreezingpoint,andyeticedidnotformintheclouds.AftertheWar,Schaeferexperimentedwithamachinethatcreatedcold,moistairsimilartotheairfoundinclouds.Toimitatethemoistairofacloud,Schaeferwouldbreatheintothemachine.Thenhewoulddropintothefreezerabitofpowder,sugar,orsomeothersubstance.Forweeksandmonthshetriedeverythinghecouldimagine.Nothinghappened.Nocrystalsoficewereformed.Noneofthesubstanceswouldserveasthecenterofasnowcrystalorraindrop.

OneJulymorning,Schaeferwasdroppinginbitsofvarioussubstancesandwatchingtheunsuccessfulresults.Finally,afriendsuggestedthattheygoto

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