Materialcomposition
Theatmosphereontheearthhasconstantgascomponentssuchasnitrogen,oxygen,andargon,aswellasgascomponentswithrelativelyfixedcontentsuchascarbondioxideandnitrousoxide.Therearealsohighlyvariablegascomponentssuchaswatervapor,carbonmonoxide,sulfurdioxide,andozone.Solidandliquidaerosolparticlessuchasdust,smokeparticles,saltparticles,waterdroplets,icecrystals,pollen,spores,bacteria,etc.areoftensuspended.
Gascomposition
Nitrogen(78.084%),oxygen(20.946%),argon(0.934%),watervapor(0.25%),carbondioxide(0.032%),neon(0.0018%)),helium(0.00052%),methane(0.0002%),krypton(0.0001%),hydrogen(0.00005%),xenon(0.000008%),ozone(0.000001%),others(0.001421%).
Mostofthemareneutralmoleculesbelow60km;from60kmupwards,theybegintoionizeundertheactionofsolarradiationduringtheday,andmostofthemareionizedabove90km.Intheupperatmosphere,somecomponentsarestilldecomposedintoatomicstates.
Evolutionofcomposition
Theearth’satmosphereisconstantlyevolvingwiththedevelopmentoftheearth,andittookalongtimetoformtoday’ssituation.
Accordingtoinference,themainelementsthatmakeuptheearth’sprimitiveatmospherearehydrogen,helium,carbon,nitrogen,oxygenandsoon.Undertheactionofgravity,theheavierelements(carbon,nitrogen,oxygen,etc.)areeasiertobepreservedbytheearth,andthelighterelementsareeasiertoescape.Atthesametime,elementswithrelativelyactivechemicalpropertiesarelikelytoformcompoundsandbepreserved(suchashydrogen,carbon,nitrogen,oxygen,etc.).Theinertandlightheliumisnoteasilypreservedbytheearth'satmosphere.Intheprocessofcompoundformation,firstly,hydrogenandcarboncombinetoformmethane,andmethanereactswithoxygentoformwaterandcarbondioxide.Inaddition,nitrogencombineswithhydrogenationtoproduceammonia,whichoxidizestoproducewaterandnitrogen.Therefore,theinitialcomponentsoftheearth’satmospherearemainlymethane,watervapor,carbondioxideandnitrogen.
About300millionyearsago,thecompositionoftheearth’satmospherechangeddramatically,namelythereductionofcarbondioxideandtheincreaseofoxygen.Theincreaseofoxygenintheatmospherehasacounterproductiveeffectonlifeactivities,whichpromotesthefurtherdevelopmentoforganisms.Respirationisalsotakingplaceinthelifeactivitiesoforganisms,thatis,absorbingoxygenandexpellingcarbondioxide.Duetothelargenumberofgreenplants,ontheonehand,thereductionofcarbondioxideintheatmosphereandtheincreaseofoxygenarecaused,ontheotherhand,anewcycleofoxygenandcarbondioxideintheatmosphereisgraduallyrealized.Thisprocesshasalong-termdevelopmentbetweentheatmosphereandorganisms.Intheprocess,mutualinfluenceandmutualrestraintareestablished,andthedynamicequilibriumstateofoxygenandcarbondioxideisestablished,andthecontentofoxygenandcarbondioxideintheatmospherealsostabilizes.
Thereductionofozoneinthemiddleatmospherecontinuestodevelop,andcontinuesfromthelastcenturytothiscentury.
Emissionsofgreenhousegases(carbondioxide,methane,freon,etc.)causedbyhumanactivitiesarealsocausingseriousglobalwarmingconcerns.
Impactsofhumanactivities
Destructionofprimevalforests
Forestsarethemainconsumersofcarbondioxideingreenplants,aswellasThemakerofoxygen.Itisestimatedthatduringthegrowingseason,thegeneralbroad-leavedforestcanabsorbaboutonetonofcarbondioxideperhectareperdayandproduce730kgofoxygen.Ifthetotalcarboncontentoftheworld’sforestsisestimatedtobe450tons,iftheaverageannualtreeis30years,thenabout55billiontonsofcarbondioxideareconsumedeveryyear.Itcanbeinferredthatsincetheprimevalforestisreducedby1/2,theannualcarbondioxideconsumedbytheforestisreducedbyapproximately55billiontons.Asaresult,thecarbondioxidecontentintheatmosphereincreases.
Themassivecombustionofcoal,petroleumandotherfuels
Thefossilfuelsformedinthepasthundredsofmillionsofyearshavebeenexploitedinlargequantities,andtheconsumptionofoilisevenmoreintense.increase.Accordingtostatistics,theworld'scoalandoilproductionwas1.8billiontonsand500milliontonsrespectivelyin1950,andbothreached2.7billiontonsin1975,anincreaseof50%andnearlyfourtimesrespectively.Becausetheconsumptionofmaterialscannotberecoveredbycombustion,theburningofalargeamountoffuelisincreasingdaybyday,resultingintheconsumptionofoxygenintheatmosphereandtheincreaseofcarbondioxide,makingthenaturalcarbonandoxygencycleimbalance.Theincreaseincarbondioxideintheatmosphereandtheconsumptionofoxygenareaseriousprobleminthelongterm.
Developmentofagriculture
Therapiddevelopmentofagriculturalproductionhascausedcropphotosynthesistoproceedonanunprecedentedscale.Circulationplayedapositiveroleinpromoting.Thishasmadecertainadjustmentstotheimbalanceofthenaturalmaterialcirculationprocesscausedbythedestructionofalargenumberofvirginforests.Intheprocessofagriculturaldevelopment,theroleoflegumerhizobiaandtheincreaseofsyntheticnitrogenfertilizersaresignificant,whichalsopromotesthenitrogencycle.
Otherimpacts
Leadandhigh-octanedecompositionproductsemittedbyjetaircrafthaveanimpactontheozonelayer.Ifnotcontrolled,itwilldestroyTheozonelayer,organismsonthesurfacewillbeexposedtoharmfulultravioletradiation.Inaddition,high-altitudeflightalsocausedanincreaseinhigh-altitudecirrusclouds.
Asfarasthesituationisconcerned,themoreprominentmanifestationoftheimpactofhumanactivitiesontheatmosphereistheincreaseincarbondioxide,dustandpollutants.Althoughhumanactivitiesalsohaveacertainimpactonthecycleofnitrogenandoxygeninnature,thecontentofnitrogenandoxygenintheatmosphereisabsolutelydominant.Relativelyspeaking,thisimpactisextremelysmall.Itcanbeconsideredthatithasbeenformedinnatureforalongtime.Thedynamicbalanceofnitrogenandoxygenhasnotbeenseverelydestroyed.
PlanetsoftheSolarSystem
The8planetsofthesolarsystemcanberoughlydividedintotwocategories:the4innerplanets(Mercury,Venus,Earth,Mars)closetothesunaresolidplanets.Theirsizeandmassarerelativelysmall.Theouterfourplanets(Jupiter,Saturn,Uranus,Neptune)aregaseousplanets,andtheirvolumeandmassaremuchlargerthantheinnersolidplanets.
Solidplanetsandgaseousplanetsinthesolarsystemhavecompletelydifferentatmosphericcompositions.Amongthesolidplanets,theatmosphereofMercuryisverythin,basicallynegligible.ThemainatmosphericcompositionofVenusandMarsisCO2,whilethemainatmosphericcompositionoftheEarthisnitrogen(N2)andoxygen(O2).Themainatmosphericcomponentsofthesurroundingfourgaseousplanetsarehydrogen(H2)andhelium(He).
Exoplanetatmosphere
Duetothelongdistance,theexistingastronomicalobservationtechnologycanprovideuswithinformationaboutthechemicalcomposition,thermalstructureandatmosphericcirculationcharacteristicsoftheexoplanetatmosphere.Verylimited.However,itcanbeinferredthattheatmosphericchemicalcompositionofexoplanetscanberoughlydividedintothefollowingtypes:
ExoplanetswhosemassismuchlessthanthemassoftheEartharesolidplanets,andtheyprobablydonothaveanatmosphere.Thisisbecausethegravitationalforceofaplanetwithasmallermassisalsosmaller,andthethermalmotionspeedofthegasmoleculesinitsatmospherecaneasilyreachtheescapespeedoftheplanet,causingthegasmoleculestoescapeintospace.Moreover,thesolarwindeasilyerodestheatmosphereandblowsgasmoleculesintospace.
However,ifexoplanetswithsmallermassesarefartherawayfromthestar,thetemperatureoftheatmosphereislower,thethermalspeedofgasmoleculesisslow,andgasmoleculesarenoteasytoescape,theseasteroidsmaystillhaveanatmosphere.
ExoplanetswhosemassismuchgreaterthanthemassoftheEarth,especiallytheJupiter-likeplanetswhosemassismorethan30timesthemassoftheEarth,shouldhavesimilaratmosphericcomponentstothoseofthesolarsystemJupiterandSaturn.HThemassesof2andHeaccountformorethan99%ofthetotalmassoftheatmosphere(theproportionsofH2andHeareabout89%and10%),thesetwocomponentsaretheBigBangThemaincomponentoftheprimitivenebulaleftbehindisalsothemostabundantmatterintheuniverse.
Exoplanetswithamassbetween10and30timesthemassoftheEarthshouldalsohaveatmosphericcompositionbasedonH2andHe,similartothesolarsystem'sUranusandNeptune.ButintheatmospheresofUranusandNeptune,theproportionofH2islowerthanthatofJupiterandSaturn,about80%,whiletheproportionofHeisrelativelyhigher,about18%.Thecontentofmethaneandammoniaintheatmosphereoficyplanetsishigherthanthatofgiantgaseousplanets.