ES 2.1: The Thin Blue Blanket Earth by the force of gravity.images.pcmac.org/SiSFiles/Schools/AL/MobileCounty/DavidsonHigh... · Environmental Science Brewer 1 ES 2.1: The Thin Blue

EnvironmentalScience

Brewer 1

ES2.1:TheThinBlueBlanket

atmosphere:amixtureagasesthatsurroundstheplanetEarth.

78%nitrogen

21%oxygen

theatmosphereisheldtotheEarthbytheforceofgravity.

DuetothesmallermassofplanetslikeMercury,lessatmospherecanbeheldinplace.

Thinneratmospheremeanslessinsulation.

Therefore,Mercuryhasgreatertemperatureextremes(840to275Fahrenheit)


Brewer 2


ConsidertheplanetVenus

approximatelythesamesizeandmassasEarth

96%oftheatmosphereiscomposedofthegreenhousegascarbondioxide.

temperaturesareneverbelow750Fahrenheit

ConsiderUranus

gasgiantwiththickcloudsofdeadlymethanegas

temperaturesaverage360Fahrenheit

NotehowmuchlargerUranusisthantheEarth.

WhateffectwouldtherelativesizeofUranushaveonthetotalatmosphereoftheplanet?


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TherelativethicknessoftheEarth'satmospheretotherestoftheEarthcanbecomparedtotheskinofanapplecomparedtotherestofanapple


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TheEarth'satmospherebecomesthinnerwithincreasingelevation.

Thisisduetoadecreaseintheforceofgravitywithincreasingdistancefromacenterofmass(i.e.centeroftheEarth)

mountainclimberw/O2tank

warmclothingduetolowtemperaturescausedbythinningatmosphere


Brewer 5


TheOzoneShieldaNaturalSunscreen

Recallapproximately21%oftheatmosphereisO2

O2moleculescanbesplitbyultravioletlightandlightning.

ThesefreeOatomsthencombinewithotherO2moleculestoformozone,O3

MoleculeBuildingactivity


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TheOzoneShieldaNaturalSunscreen

Ozoneismeasureinpartspermillion(ppm)byvolume

Thecycleofozonecreation(UVlight)anddestruction(nitricoxide)iscontinuousandnatural.

OzoneformationdependsontheamountofUVlightandtemperature

Equilibriumisachievedwhentherateofcreationequalstherateofdestructionofozone.

Ozonedepletionoccurswhentherateofdestructionisgreaterthanthatofcreation.


Brewer 8


CFCsTheRisksandBenefitsofTechnology

Beginninginthe1970's,scientistsbegantostudytheeffectofchemicalsproducedbyhumanactivitiesontheozoneshield

PaulCrutzendiscoveredthatnitrogenoxidesfromsupersonicjetscoulddamagetheozonelayer.


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chlorofluorocarbons(CFC's):compoundscontainingcarbon,fluorine,andchlorinethatcandestroytheozonelayer

WhenCFCsmeetOzone.mpeg

CharacteristicsofCFC's:1)nontoxic2)nonflammable3)inexpensivetoproduce

Usedasareplacementcoolantinrefrigeratorsandairconditionersbecausethemethylchlorideusedwastoxic.

Extremelystableinthetroposphere,whereUVlightsplitschlorinefromCFC's.AsingleClatomcanthendestroy100,000ozonemolecules.

CFC'seventuallyreturntotheloweratmosphereandarewashedoutbyrain.

SMART Notebook


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OzoneReactions

FormationofOzone

O2+UVlight>O+O

O+O+2O2+catalyst>2O3

Net:3O2>2O3

NaturalDestructionofOzone

O3+NO>O2+NO2

O3+UVlight>O2+O

NO2+O>NO+O2

Net:2O3>3O2

OzoneAccumulation

3O2>2O3

3O2


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CFC'sAttackonOzoneReaction

CFCl3+UVlight>CFCl2+Cl

Cl+O3>ClO+O2

O3+UVlight>O2+O

ClO+O>Cl+O2

Cl+O3>ClO+O2

Result2O3>3O2


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BiologicalEffects

OzoneprotectslifefromharmfulUV(blacklight)

UVtypes(bywavelength)

UVA:necessaryforsynthesisofvitaminDintheskin

UVB:causesagingoftheskin,skincancers,cataracts,andmayimpairimmunesystemresponse

notnecessaryforphotosynthesis,andcanbeharmfultoplantsandmicrobes

plantsbecomemoresusceptibletoinsectsandpathogens

UVC:mostdeadlyformofUV,butabsorbedbyozoneandoxygeninatmosphere


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BiologicalEffects

CO2,H2O,nutrientsandheatarefactorsinhowmucheffectUVradiationwillhaveonplants

UVmayalsoreducetherateofphotosynthesisofphytoplanktonintheocean.

FrogeggsandcoralreefsarealsosensitivetoUVlightandinterfereswiththeirdevelopment.

Marineecosystemsnearthepolesexperiencethegreatesteffects.


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WarningNotHeeded

ScientistsfirstdiscoveredthelinkbetweenCFC'sandozonedepletionin1974.

In1977theU.S.,Canada,andothersbannedtheuseofCFC'sinaerosols

Althoughothersourcesexistedatthattime,industrylobbyistsenticedpoliticianstoallowindustrialuseofCFC's.

Presently,theozoneisbeingdestroyedatafasterratethanitisbeingproduced.

OzonedepletionisgreatestoverAntarctica.Duringthespring,Antarctica'suniqueweatherpatterns furtherthedepletion.

Contrarytopopularbelief,thereisnophysical"hole"intheozonerather,theozonelayerisverythinintheseregions.


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TheMontrealProtocol

ThemajorcauseofozonedestructionischlorinefromCFC's

Solutions:

1.StopproductionofCFC's

2.PreventthereleaseofCFC'sintheatmosphere

ProtocolnowseekstotaleliminationofCFC's

Theglobalnatureofozonerequiresinternationalcooperationinordertoprovideprotection

Ozonewillnotreturntopre1980levelsuntil2065.


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FindingAlternatives

CFC'sarebannedinindustrializedcountries

exceptions:whennootheroptionisavailable

DevelopingcountriesstilluseCFC's

RecycledCFC'scanbeusedforequipment

HighcostofreplacementsencouragesillegaluseofCFC's

HCFC'sarelessstableandfewermoleculesreachtheatmosphere

productionmuststopby2030

replacementchemicalmustbe:

1.nonflammable

2.noncorrosive

3.lowtoxicity

4.reasonablypriced

Halonsareusedinfireexstinguishers

replacementbyCO2

CO2onlyworksforcertainkindsoffires

CO2weighsmore(impracticalforairplanes)

HCFCmolecule

CFCmolecule


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WhatYouCanDo

Recycleyourrefrigerants(don'tforgetyourcar)

Avoidthesunbetween10and3

UsesunscreenthatblocksUVAandUVB

WearsunglassesthatblockUVradiation

Attachments

WhenCFCsmeetOzone.mpeg

SMART Notebook

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ES 2.1: The Thin Blue Blanket Earth by the force of gravity.images.pcmac.org/SiSFiles/Schools/AL/MobileCounty/DavidsonHigh... · Environmental Science Brewer 1 ES 2.1: The Thin Blue