Evolution of Earth's Atmosphere: Past, Present & Future

1. MADISON’S CURRENT WEATHER Madison Weather at Madison Weather at 1000 AM CDT WED JUN 18 2003Updated twice an hour at :05 and :25Sky/Weather: MOSUNNY Temperature: 79 F (26 C) Dew Point: 63 F (17 C) Relative Humidity: 57% Wind: W7 MPH Barometer: 29.89F (1012.2 mb)

2. Current Surface Weather Map with Isobars (“iso” = equal & “bar” = weight), Fronts & Radar Isobars

3. Current Surface Weather Map with Isobars (“iso” = equal & “bar” = weight), Fronts & Radar Isobars

4. Clouds Current Visible Satellite Image Current Visible Satellite Image

5. Current Temperatures (°F) & Isotherms(“iso” = equal +”therm” = temperature)

6. Yesterday’s Surface Weather Map with Isobars (“iso” = equal & “bar” = weight), Fronts & Radar Isobars

7. Current Surface Weather Map with Isobars (“iso” = equal & “bar” = weight), Fronts & Radar Isobars

8. Tomorrow AM Forecast Map

9. ATM OCN 100 – Summer 2004LECTURE 2A PHYSICAL & CHEMICAL COMPOSITION of EARTH’S ATMOSPHERE • A. PRACTICAL QUESTIONS • What makes Planet Earth special? • How has the atmosphere evolved?

10. Earth-Rise (Apollo Mission)

11. SUNRISE FROM SPACEFrom STS-52 (JSC-NASA)

12. B. PRESENT EARTH’S ATMOSPHERE • Background • Early Greek Thought • The 4 Elements: Earth, Air, Water, Fire. • “Modern” Chemistry (since 18th century) • Element • Compound • Mixture • Chemical Composition • Air is a mixture • With the following gases:

13. Atmospheric Gases isolated by 18th Century Chemists • Nitrogen (N2) D.Rutherford 1772 • Oxygen (O2) J.Priestley & A. Lavoisier 1774 • Carbon Dioxide (CO2) J. Black 1756

14. See Table 2.1 Moran (2002)

15. B. PRESENT EARTH’S ATMOSPHERE (con’t.) • Vertical Variations of Atmospheric Composition • Criterion • Chemical • Divisions • HOMOSPHERE • HETEROSPHERE • Where ...

16. VERTICAL COMPOSITION VARIATIONS (con’t.) • HOMOSPHERE • “Homo” = same (percentage composition); • Turbulent mixing; • Below 80 km altitude. • HETEROSPHERE • “Hetero” = different (composition); • Fractional diffusion (by molecular weight); • Above 80 km altitude.

17. CONSTITUENTS OF AIR in the HOMOSPHERE(Below 80 km) • Principal Permanent Gases of “Dry Air” • Principal Variable gases • Anthropogenic Gases • Aerosols • Liquids or solids suspended in Atmosphere • Clouds • Liquid droplets or ice crystals in Atmosphere

18. PRINCIPAL FIXED GASESin the “Dry” Homosphere • Nitrogen (N2) • Importance in Food Chain (Nitrogen Fixation) • Oxygen (O2) • Critical Importance for Life (Respiration) • Argon (Ar) • Unknown Importance • Carbon Dioxide (CO2) • Critical Importance for Life (Photosynthesis) (also Asphyxiation)

19. See Table 2.1 Moran (2002)

20. PRINCIPAL VARIABLE GASESin the Homosphere • Water Vapor (H2O) <4% by volume • Carbon Dioxide (CO2) 360 ppm = 0.036% • Methane (CH4) < 1700 ppb = 0.00017% • Ozone (O3) < 8 ppm = 0.0008%

21. Recent Atmospheric CO2 ConcentrationsSee Fig. 3.24, Moran (2002)

22. Mauna Loa Observatory, HI

23. Ozone • A paradox • Good and Bad • Natural production & destructionwhere…

24. Ozone FormationFigure 3.18 Moran (2002)

25. Ozone Destruction (Natural)Figure 3.18 Moran (2002)

26. Ozone • A paradox • Natural production & destruction • Location in Atmosphere

27. 8 ppmv = 0.0008%

28. ANTHROPOGENIC SUBSTANCES • Chlorofluorocarbons (CFCs) • Volatile Organic Compounds • (Hydrocarbons) • Oxides of nitrogen (NO, NO2) • Oxides of carbon (CO, CO2) • Sulfur compounds (H2S, SO2,SO3) • Suspended particulates

29. AEROSOLS • What they are • Suspended solid particles or liquid droplets in atmosphere. • Sources • Natural • Human activity • Where….

30. Aerosols from Wildfires11 May 2000(NOAA-15)

31. Aerosols from Colorado Wildfires10 June 2002(SSEC - MODIS)

32. Aerosols from VolcanoesMt. St. Helens, WA May 1980

33. Volcanic Plume from Mt. Etna23 July 2001(NOAA-14)

34. Aerosols-Dust from Mongolia10 Apr 2001

35. Aerosols from Blowing Dust

36. Aerosols from Sea Spray (Calif. Coast)

37. Aerosols from Natural Vegetationin Great Smoky Mtn. Nat'l Park, NC-TN

38. Aerosols from Urban PollutionMadison (from Space Science & Eng. Center)

39. Relative sizes of dust • Coarse sand 2 mm • Beach sand 0.5 mm • Granulated sugar 0.4 mm • Table salt 0.1 mm • Typical Mideast particles • Fine sand 0.06 mm • Silt, dust 0.05 mm or less • Talcum powder 0.01 mm

40. PRINCIPAL VARIABLE GASESin the Heterosphere(above 80 km) • Diatomic nitrogen (N2) 85 to 200 km • Monatomic oxygen (O) 200 to 1100 km • Helium (He) 1100 to 3500 km • Atomic hydrogen (H) 3500 to 11,000 km

41. C. ORIGIN & EVOLUTIONof Earth’s Atmosphere • How did our current atmosphere evolve? • General History of the Atmosphere • 4.5 billion yr ago - Solar System formed • And then…

42. Early Atmospherebefore 3 billion years BP Outgassing ofH2O CO2 CH4 NH3 Formation of Oceans

43. Fossil algae 2 billion yrs old vs. living algae Photosynthesis Water + Carbon Dioxide + Sunlight ---> Sugar + Oxygen 6H2O + 6CO2 + Sunlight ---> C6H12O6 + 6O2

44. C. ORIGIN & EVOLUTION of Earth’s Atmosphere

45. ATMOSPHERIC ORIGIN & EVOLUTION (con’t) • Rationale • Planet Earth is special because of large amounts of O2; • Atmosphere & Life Co-evolved. • Human Intervention • Humans could possibly affect concentrations of some gases, with following…

46. Enhanced “Greenhouse Effect” • Background

47. Enhanced “Greenhouse Effect” • Increases in “Greenhouse Gases” • CO2 and CH4 • Why more CO2? • Burning of fossil fuels • Deforestation • Changes in Sea Surface Temperature

48. Global CO2 EmissionsMarland, et.al. 2001Carbon Dioxide Information Analysis Center

50. CO2 measurements at Mauna Loa, HI See Fig. 3.24 Moran (2002)