Average Atmospheric Composition Permanent Variable SOURCE to atmosphere SINK removal from atmosphere N 2 Fixed by soil bacteria Fixed by ocean phytoplankton Lightning Denitrification by anaerobic ID: 1025835
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1. EVSC 3300ATMOSPHERIC COMPOSITION
2. Average Atmospheric CompositionPermanentVariable
3. SOURCE(to atmosphere)SINK(removal from atmosphere)N2Fixed by soil bacteriaFixed by ocean phytoplanktonLightningDenitrification by anaerobic bacteria in decaying plants/animalsO2Aerobic bacterial processesCombustionRespiration (oxidation: food to energy)Ocean phytoplanktonPhotosynthesis6 CO2 + 6 H2O C6H12O6 + 6 O2Vis. lightCO2PhotosynthesisFixation by ocean phytoplanktonDissolved directly into ocean surfaceRespirationCombustionSTORAGE: limestone sediments, marine shells, fossil fuels
4. Mauna Loa Carbon Dioxide RecordPre-industrial background 280 ppmCurrent level 412 ppm
5. https://www.esrl.noaa.gov/gmd/ccgg/covid2.html mean seasonal cycle(gray=1 standard deviation)2020 so far
6. SOURCE(to atmosphere)SINK(removal from atmosphere)CH4Interaction with hydroxyl in atmosphereSoilsAnaerobic processes(wetlands, rice paddies) Bovine flatulenceTermitesBiomass burning N2OStratospheric photochemistry (converted to NOx)Bacteria in soils/oceans(nitrification)Combustion (cars, biomass)FertilizersO3Also chlorine, bromine, NOxCH4 + OH CH3 + H2O O2 + OO3O3 + uvO2 + OH2OCondensation onto surfacesPrecipitationDepositionEvaporation from open waterSublimation (from ice)Transpiration (through plants)
7. Greenhouse Gas Trends Since 1979(NOAA: Earth System Research Laboratory)Montreal Protocol
8. Average Atmospheric CompositionPermanentVariableCF2Cl2; CFCl3
9. Aerosols
10. If you are reading along in the textbooks, I will periodically provide updates in the slideshowsregarding the sections that have just been covered: N = Neiburger A = AhrensThe previous material on atmospheric compositionis N (pp. 32–36), A (pp. 4–10)
11. Vertical Structure of the AtmosphereNewton’s Second Law of Motion: = resultant force [Newtons, N = kg m/s2] = mass [kg] = acceleration [m/s2]Pressure (p) is weight of air (force) acting per unit area (A) = Pa (Pascals)
12. Mercury Barometer
13. Variation of Pressure/Density with Height
14. Stationvs.Sea-levelPressurestation pressure—barometer measurementcorrection for station elevationresulting map of sea-levelpressure variations (surface map)
15. “Tawny” Kitten(a.k.a. “Tawny Mocha Chip Marshmallow Paws”)
16. How thick is Earth’s atmosphere? (Or how high is the top?)Light is not scattered (sky isdark) at 80 km (50 miles)99% of the total mass of the atmosphere can be found below 31 kmAtmospheric gasses are well-mixed below 100 km (60 miles) = homosphere(above homosphere, separated by molecular weight = heterosphere)
17. VARIATION OF PRESSURE/DENSITY WITH HEIGHT
18. Mean Sea-level Pressure in Various UnitsVALUE UNITS101.325 kPa kiloPascals1013.25 hPa** hectoPascals101,325 Pa Pascals101,325 Nm–2 Newtons per square meter101,325 kgm–1s–2 kg-mass per meter per second squared1.033227 kgcm–2 kg-force per meter per second squared1013.25 mb** millibars1.01325 bar bars1.033227 atm atmosphere14.69595 psi pounds-force per square inch2116.22 psf pounds-force per square foot760 Torr TorrMeasured in a liquid in glass barometer:29.92126 in Hg inches of mercury760 mm Hg millimeter of mercury33.89854 ft H2O feet of water10.33227 m H2O meters of waterNote: 100 Pa = 1 mb**know this one!
19. Pressure can be used as a meaningful vertical scale.Variation of Pressure with HeightN (94–96, 99–101)A (202–206)
20. AverageVerticalTemperatureStructureof AtmosphereABA: HomosphereB: Heterosphere
21. Lapse rate: rate of temperature decline with height troposphere: g =6.5°C/km (5.5°F/1000 feet)Inverted lapse rate (“inversion”): temperature increaseswith heightIdeal Gas Law: rRT r (density) = At a given pressure, cold air is denser than warm air==ht.coldwarmSTABLEcoldwarmUNSTABLE
22. AverageVerticalTemperatureStructureof AtmosphereABA: HomosphereB: Heterosphere
23. 250250250250250230230230230230230250230230250250250230210210210210202210210201284272270270250230230250270290290270270270270210tropopausestratopausestratopausetropopauseNorthern Hemisphere Temperature, by Latitude and AltitudeN (36–47); A (10–17)
24. Scales of Motion