职称英语理工A考前集训练习题2017年职称英语理工A考前集训练习题thenindeedyoustandonshakyground.以下是小编为大家搜索整理的2017年职称英语理工A考前集训练习题，希望能给大家带来帮助!更多精彩内容请及时关注我们应届毕业生考试网!TheNorthernLightsTheSunisstormyandhasitsownkindofweather.ItissohotandactivethateventheSun’sgravitycannotholditsatmosphereincheck1!EnergyflowsawayfromtheSuntowardtheEarthinastreamofelectrifiedparticlesthatmoveatspeedsaroundamillionmilesperhour2.Theseparticlesarecalledplasma,andthestreamofplasma3comingfromtheSuniscalledthesolarwind.ThemoreactivetheSun,thestrongerthesolarwind.ThesolarwindconstantlystreamstowardtheEarth,butdon’tworrybecauseaprotectivemagneticfieldsurroundsourplanet.ThesamemagneticfieldthatmakesyourcompasspointnorthalsosteerstheparticlesfromtheSuntothenorthandsouthpoles.ThechargedparticlesbecometrappedinmagneticbeltsaroundtheEarth.WhenalargeblastofsolarwindcrashesintotheEarth’smagneticfield,themagneticfieldfirstgetssqueezedandthenthemagneticfieldlinesbreakandreconnect.4ThebreakingandreconnectingofthemagneticfieldlinescancauseatomicparticlescalledelectronstrappedinthebeltstofallintotheEarth’satmosphereatthepoles.AstheelectronsfalltotheEarth,theycollidewithgasmoleculesintheatmosphere,creatingflashesoflightinthesky.Eachatmosphericgasglowsadifferentcolor.Oxygenandnitrogenglowsredandgreenandnitrogenglowsviolet-purple.Asthesevariouscolorsglowanddanceinthenightsky,theycreatetheNorthernLightsandtheSouthernLights.Watchingaurorasisfunandexciting,butnormallyyoucanonlyseetheminplacesfarnorthlikeAlaskaandCanada.Themovementoftheauroraacrosstheskyisusuallyslowenoughtoeasilyfollowwithyoureyesbuttheycanalsopulsate,flicker,orevenmovelikewaves.Duringsolarmaximum,5aurorasareseenasfarsouthasFlorida,evenMexico!6Aurorasoftenseemtobeveryclosetotheground,butthelowestauroraisstillabout100kilometersabovetheground,adistancemuchhigherthancloudsareformedorairplanescanfly.Atypicalaurorabandcanbethousandsofkilometerslong,afewhundredkilometershigh,butonlyafewhundredmetersthick.Wehopeyouareabletotraveltofar-northplaceslikethe