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1、WindEnergy--EnergyfromMovingAirWindissimpleairinmotion.Itiscausedbytheunevenheatingoftheearthsurfacebythesun.Sincetheearthsurfaceismadeofverydifferenttypesoflandandwater,itabsorbsthesunheatatdifferentrates.Duringtheday,theairabovethelandheatsupmorequick
2、lythantheairoverwater.Thewarmairoverthelandexpandsandrises,andtheheavier,coolerairrushesintotakeitsplace,creatingwinds.Atnight,thewindsarereversedbecausetheaircoolsmorerapidlyoverlandthanoverwater.Inthesameway,thelargeatmosphericwindsthatcircletheeartha
3、recreatedbecausethelandneartheearth'sequatorisheatedmorebythesunthanthelandneartheNorthandSouthPoles.Today,windenergyismainlyusedtogenerateelectricity.Windiscalledarenewableenergysourcebecausethewindwillblowaslongasthesunshines.TheHistoryofWindSinceanci
4、enttimes,peoplehaveharnessedthewindsenergy.Over5,000yearsago,theancientEgyptiansusedwindtosailshipsontheNileRiver.Later,peoplebuiltwindmillstogrindwheatandothergrains.TheearliestknownwindmillswereinPersia(Iran).Theseearlywindmillslookedlikelargepaddlewh
5、eels.Centurieslater,thepeopleofHollandimprovedthebasicdesignofthewindmill.Theygaveitpropeller-typeblades,stillmadewithsails.Hollandisfamousforitswindmills.Americancolonistsusedwindmillstogrindwheatandcorn,topumpwater,andtocutwoodatsawmills.Aslateasthe19
6、20s,Americansusedsmallwindmillstogenerateelectricityinruralareaswithoutelectricservice.Whenpowerlinesbegantotransportelectricitytoruralareasinthe1930s,localwindmillswereusedlessandless,thoughtheycanstillbeseenonsomeWesternranches.Theoilshortagesofthe197
7、0schangedtheenergypictureforthecountryandtheworld.Itcreatedaninterestinalternativeenergysources,pavingthewayforthere-entryofthewindmilltogenerateelectricity.Intheearly1980swindenergyreallytookoffinCalifornia,partlybecauseofstatepoliciesthatencouragedren
8、ewableenergysources.Supportforwinddevelopmenthassincespreadtootherstates,butCaliforniastillproducesmorethantwiceasmuchwindenergyasanyotherstate.ThefirstoffshorewindparkintheUnitedStatesisplannedforanareaoffthecoastofCapeCod,Massa
