power point presentation in atmospheric chemistry

this will provide quick discussion on atmospheric chemistry and some other details on atmosphere including layers of the atmosphere and environmental problems in the atmosphere

1. Atmospheric Chemistry
•AtmosphericchemistryisabranchofAtmospheric
ScienceinwhichChemistryoftheEarth’satmosphere
andthatofotherplanetsisstudied.
•Itisamultidisciplinaryapproachofresearchanddraws
on:
oEnvironmental Chemistry
oPhysics
oMeteorology
oComputer Molding
oOceanography
oGeology and
oVolcanology and other discipline

2. Topic-ATMOSPHERE CHEMISTRY

3. EARTH’S ATMOSPHERE
Earth’s atmosphere has a series of layers, each with its
own specific traits.
Moving upward from ground level, these layers are named
oTroposphere
oStratosphere
oMesosphere
oThermosphere and
oExosphere.
The exosphere gradually fades away into the realm of
interplanetary space.

4. Atmospheric Chemistry
EARTH’S
ATMOSPHERE
Exosphere
o1600 km; Very high Temp.,
oH
2, HE, Outer Space
Thermosphere
o90-500 km; -92 to 1200
o
CTemp.,
oO
2, NO+
Mesosphere
o50-90 km; -2 to -92 oCTemp,
o(Ionoshere: O
+
2, O+ , NO+ , e-)
Stratosphere
o11-50 km; -56 to -2
o
CTemp,
oO
3 (Ozone Layer: 15 km)
Troposphere
o0-11 km; 15 to -56
o
CTemp,
oN
2, O
2, CO
2, H
2O

5. Troposphere
Thetroposphereisthelowestlayer
ofouratmosphere.
Startingatgroundlevel,itextends
upwardtoabout10km(6.2miles
orabout 33,000feet)abovesea
level.
Wehumansliveinthetroposphere,
andnearlyallweatheroccursinthis
lowestlayer.

6. Mostcloudsappearhere,mainly
because99%ofthewatervaporin
theatmosphereisfoundinthe
troposphere.
Air pressuredrops and
temperaturesgetcolder,asyou
climb higher in the
troposphere.
Troposphere

7. Stratosphere
Thestratosphereextendsfromthe
topofthetropospheretoabout50
km(31miles)abovetheground.
Theinfamousozonelayerisfound
withinthe stratosphere.
Ozonemoleculesinthislayerabsorb
high-energyultraviolet(UV)light
fromtheSun,convertingtheUV
energyintoheat.
Unlikethetroposphere,the
stratosphereactually gets
warmerthehigheryougo!

8. Stratosphere
Thattrendofrisingtemperatures
withaltitudemeansthatairinthe
stratosphere lacks the
turbulenceandupdraftsofthe
tropospherebeneath.
Commercialpassengerjetsflyinthe
lower stratosphere,partly
becausethisless-turbulentlayer
providesasmootherride.
Thejetstreamflowsneartheborder
betweenthe troposphereandthe
stratosphere.

9. Mesosphere
Abovethestratosphereisthe
mesosphere.
Itextendsupwardtoaheightof
about85km(53miles)aboveour
planet.
Mostmeteorsburnupinthe
mesosphere.Unlikethestratosphere,
temperatures onceagaingrow
colderasyouriseup through
themesosphere.

10. Mesosphere
ThecoldesttemperaturesinEarth's
atmosphere,about-90°C(-130°F),
are foundnearthetopofthis
layer.
Theairinthemesosphereisfartoo
thintobreathe;airpressureatthe
bottomofthelayeriswellbelow1%
ofthepressureatsealevel,and
continuesdroppingasyougo
higher.

11. Thermosphere
Thelayerofveryrareairabovethe
mesosphere iscalledthe
thermosphere.
High-energyX-raysandUV
radiationfromthe Sunare
absorbedinthethermosphere,
raisingitstemperaturetohundreds
orattimesthousandsofdegrees.
Theairinthislayerissothinthatit
wouldfeelfreezingcoldtous!

12. Thermosphere
Thethermosphereismorelikeouter
spacethanapart ofthe
atmosphere.Manysatellitesactually
orbit Earth within the
thermosphere!
Thetopofthethermospherecanbe
found anywherebetween
500and1,000km(311to621miles)
abovetheground.

13. Thermosphere
Temperaturesinthe upper
thermospherecanrangefromabout
500°C(932°F)to2,000°C(3,632
°F)orhigher.
Theaurora,theNorthernLightsand
Southern Lights,occurinthe
thermosphere.

14. Exosphere
Althoughsomeexpertsconsiderthe
thermospheretobetheuppermost
layerofouratmosphere, other
considertheexospheretobethe
actual "finalfrontier"ofEarth's
gaseousenvelope.
Asyoumightimagine,the"air"in
theexosphereisvery,very,verythin,
makingthislayerevenmorespace-
likethanthethermosphere.

15. Exosphere
Infact,airintheexosphereis
constantly-thoughverygradually-
"leaking"out of Earth's
atmosphereintoouterspace.
Thereisnoclear-cutupper
boundarywherethe exosphere
finallyfadesawayintospace.

16. Exosphere
Differentdefinitionsplacethetopof
theexospheresomewherebetween
100,000km(62,000miles)and
190,000km(120,000miles)above
thesurfaceofEarth.
Thelattervalueisabouthalfwayto
theMoon!

17. Theionosphereisnotadistinctlayer
liketheothermentionedabove.
Theionosphereisaseriesofregions
in partsofthemesosphereand
thermospherewherehigh-energy
radiationfromtheSunhasknocked
electronsloosefromtheirparent
atomsandmolecules.
Ionosphere

18. Theelectricallychargedatomsand
moleculesthatareformedinthisway
are calledions,givingthe
ionosphereitsnameandendowing
thisregionwithsome special
properties.
Ionosphere

19. Atmospheric Chemistry
ThecompositionandchemistryoftheEarth'satmosphere
isofimportanceforseveralreasons.
But,primarilybecauseoftheinteractionsbetween
oAtmosphereand
oLivingorganisms.
ThecompositionoftheEarth'satmospherechangesas
resultofnaturalprocessessuchas:
oVolcanoemissions
oLightningand
oBombardmentbysolarparticlesfromcorona.

20. Atmospheric Chemistry
Ithasalsobeenchangedbyhumanactivityandsomeof
thesechangesareharmfulto:
oHumanhealth
oCropsand
oEcosystems.
Examplesofproblemswhichhavebeenaddressedby
atmosphericchemistryinclude:
oAcidrain
oOzonedepletion
oPhotochemicalsmog
oGreenhousegasesand
oGlobalwarming.

21. Acid rain
This phenomenon came to attention in the
1970s
Burningcoal,oilandnaturalgasinpower
stationsmakeselectricity,givingoff
Sulphurdioxidegas.
Burningpetrolandoilinvehicleengines
givesoffNitrogenoxidesasgases.
PresenceofH
2SO
4(relatedtoSO
2from
coalcombustion)andHNO
3(fromNO
2)

22. Acid rain
Inthepresenceoflightningandthunderstorm,the
nitrogenoftheatmospherecombineswithoxygento
formnitricoxide(NO),whichinturncombineswith
oxygentogivenitrogendioxide.
N
2 + O
2 ————→2 NO
2 NO + O
2———— →2 NO
2
Intheatmosphere,nitrogendioxidereactswithwater
vapourproducingnitricacid,whichiswasheddownas
acidrain.
3 NO2 + H
2O ————→2 HNO
3 + NO
TheformationofNitricacidandSulphuricacidas
secondarypollutantsintheatmosphereleadstoacid
rain.

23. Acid rain
Allrainisacidicwithorwithoutairpollution.
Thisisduetothenaturalpresenceofcarbon
dioxideinthe atmospherewithdissolvesin
raindropsofrainwater(evenmoisturepresent
intheatmospheredoesthesamefunction)to
formCarbonicacid.
CO2 + H2O →H2CO3

24. Acid rain
Duetotheabovereactioncarbondioxidecandissolvein
wateruntilthesolutionbecomessaturated.
ThisresultsintherainwaterattaininganacidicpHof
5.6
Duetothis,thepurestformofrainreachestheearthas
anacidicsolutionofpH5.6
AciditycausesEnvironmentalproblemslike
oDestructionofvegetation
oMarinelife
oCorrosionand
oEtchingofbuildingsthatareexposedtoatmosphere.

25. Howozoneisformed?
Ozonedepletion

26. Man-made causes of depletion of ozone layer:
•Themaincauseforthedepletionof
ozoneisdeterminedasexcessive
releaseofchlorineandbromine
fromman-madecompoundssuchas
chlorofluorocarbons(CFCs).
•CFCs(chlorofluorocarbons)
•Halogens
•CH3CCl3(Methylchloroform)
•CCl4(Carbontetrachloride)
•HCFCs (hydro-
chlorofluorocarbons)
•Hydrobromofluorocarbonsand
•Methylbromidearefoundto
havedirectimpactonthe
depletionoftheozonelayer.
Ozonedepletion

27. Man-made causes of depletion of ozone layer:
•ThesearecategorizedasOzone-
DepletingSubstances(ODS).
•Chlorofluorocarbonsarereleased
intotheatmospheredueto:
oCleaningAgents
oCoolantsinrefrigerators
oPackingmaterial
oAirconditioning
oAerosolspraycansetc.
Ozonedepletion

28. Why is the ozone layer important?
UV-Radiation DNA -damage
Skin Cancer
Ozonedepletion

29. Greenhouse gases & Global warming
•Theatmosphereistheairaroundthesurface
oftheearth.Itismadefromamixtureof
gases.Weneeditforanimalsandplantsto
survive.
•Someofthegasesactlikeablanket,trapping
heat.Thesegasesarecalled‘Greenhouse
gases’.
•Themaingreenhousegasesare:
oCarbon dioxide
oMethane
oNitrous oxide
oOzone
oWater vapour
oHalocarbons

30. Greenhouse gases & Global warming
•Thisisknownasthe‘Natural
GreenhouseEffect’.
•Withoutit,theearthwouldbemuch
colder.
•Theheatingoftheearththroughhuman
activitiesiscalledthe‘Enhanced
GreenhouseEffect’andthisiscausing
theearthtoheatup,orGlobalwarming.
•Globalwarmingdoesn’tjustmeanthat
theearthgetshotter,itmeansthatthe
wholeclimateischanging.

31. Natural
Greenhouse
effect
Moreheatis
trapped and
causesglobal
warming
Atmosphere traps
some heat
Some heat
goes out to
space
Quitealotofheat
istrappedandthe
earthiswarm
enoughforlife.
Enhanced
Greenhouse
effect
Heat radiates
from the earth
Heat radiates
from the earth
Atmosphere
has more
greenhouse
gases
Atmosphere traps
more heat
Less heat
goes out
to space