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- 2. Formation of the Earth Apollo Space Program (1960’s) Otto Schmidt Cosmic Dust Planet (100 million years)
- 3. Thermal Consequences Earth’s Core Molten Fe ( Density 7.86 g/cc) Ni ( Density 8.9 g/cc) Outer
- 4. Formation of the Mantle The less dense material will go toward the surface (Polar Oxides of
- 5. Isotope Distribution of the Earth Investigation of the History of the Earth primarily relied on isotope
- 6. Appearance of the Atmosphere Did the atmosphere suddenly appear ? Isotope Analysis gives a clue Claude
- 7. Isotopes of Xe Xenon has 9 isotopes With the following distribution 124Xe 0.1% , 126Xe 0.09%,
- 8. Distribution of Xe isotopes Nucleosynthesis gives rise to 129Xe β- Decay of 129I 129Xe (t1/2 =
- 9. Differentiation The Atmosphere was formed due to OUT GASSING of the mantle (Heat) & Volcanic Activity
- 10. Age of differentiation From the ratio of 129 Xe in the Mantle to that of 129
- 11. Ratios of Isotopes The Argon trapped in Mantle evolved from the radioactive decay of 40K 40K
- 12. Conclusions from Isotope Analysis ∴ If outgassing occurred at the beginning the atmosphere would not contain
- 13. Collecting the evidence The other 15% has arisen due to slow release over 4.4 billion years
- 14. Early Atmosphere Majors: CO2, N2, H2O (Water Vapour) Traces: CH4, NH3, SO2, HCl Water Vapour Oceans
- 15. Origin of Life Stanley Miller (1950) “ Early Earth ” Experimental Setup CH4, NH3, H2, H2O(g)
- 16. Formation of Simple Amino Acids Glycine was found How Glycine (NH2CH2COOH) Formed HCOH + NH3 +
- 17. Murchison Meteor A number of the compounds discovered in the discharge fractions are precursors to life.
- 18. Early Energy System The first living organisms gained their energy by a fermentation of the organic
- 19. Role of Blue Green Algae Blue Green Algae & Photosynthetic Bacteria developed to use water as
- 20. Decline of Anaerobic Bacteria Problem for Anaerobic Organisms Evidence of the appearance of Oxygen is indicated
- 21. Oxygen Rich Planet Oxygen Rich Planet The build up of Oxygen in the atmosphere led to
- 22. Oxygen Rich Planet Respiration utilized the photosynthetic Compounds (Sugar ) to produce Energy (CH2O)n + nO2
- 23. The trouble with oxygen The ultilization of oxygen in producing energy resulted in emergence Eukarotic cells
- 24. The present atmosphere The present atmosphere has arisen from (1) The distance of the earth from
- 25. Distance from the Sun The distance from the Sun determines the kinetic energy (KE) of the
- 26. Influence of Earth’s Mass The ability of molecules to remain in the atmosphere is also related
- 27. Escape Velocity Escape Velocity (Ve) Ve = (2Gm/R)1/2 m = Mass of the Planet G= Universal
- 28. Escape Velocity The ability of molecules to remain in an atmosphere is related to the mass.
- 29. No H or He in Earth’s Atmosphere At 600 K (Upper Atmosphere ) For H atoms
- 30. Little CO2 in atmosphere For Oxygen only 1 in 1084 atoms exceeds the escape velocity .This
- 31. Earth ,Venus & Mars Surface Characteristics of Planets Temperature Pressure (bar)* Venus 732 K (459oC) 90
- 32. Distribution of Gases on Earth Venus & Mars Composition of Planet’s Atmospheres in % CO2 N2
- 33. Role of Shellfish Presence of Life on Earth has removed Carbon dioxide from the Atmosphere and
- 34. Triple point of H2O P(H2O) in Atmospheres Temperature K Venus Earth Mars ICE WATER VAPOUR Triple
- 35. Water ( Solid,Liquid, Gas) The Surface temperature of the Earth at 1 atmosphere Pressure is close
- 36. Super Greenhouse & Acid Rain On Venus ,the high level of CO2 and its distance from
- 37. Current Atmosphere Composition of Current Atmosphere %Vol N2, O2, Ar, CO2, H2O 78.08 20.95 0.93 0.03
- 38. Present Level of Oxygen The present level of Oxygen in the atmosphere is balanced at a
- 39. Structure of Atmosphere Earth’s Atmosphere Earth’s Surface Troposphere Stratosphere Mesosphere Thermosphere REGION 10-16 km (-56oC) 50
- 40. Ozone Layer Ozone in the Stratosphere ≈ 16 - 50km above the Earth’s Surface acts as
- 41. Ozone and Radiation Oxygen that lies above the stratosphere filters out UV light 120nm - 220nm
- 42. Effects of Reduction in Ozone (Effects of Reduction) 1% Reduction In O3 2% increase in UV-B
- 43. Chlorofluorocarbons & Ozone Destruction of the Ozone Layer discovered in 1970’s by CFC’s ( Chlorofluorocarbons) First
- 44. Ozone Protection Protection O2 + hν 2O. O. + O2 O3 O3 + hν O. +
- 45. Ozone Destruction Destruction CFCl3 Cl. Chlorine (UV-C, UV-B) Radical Cl. + O3 O2 + ClO. ClO.
- 46. Control of CFC’s CFC’s are now under strict control and their use has been curtailed. Australia
- 47. Uses of CFC’s Compound Use CFC- 11 CFCl3 Refrigeration, aerosol, foam CFC-12 CF2Cl2 sterilization, cosmetics food
- 48. Lifetime of CFC’s Compound Ozone Depleting Lifetime(yrs) Potential CFC- 11 1.0 65 -75 CFC-12 1.0 100
- 49. Naming of CFC’s ( 90 Rule) CFC’s name is related to its Formula. CFC 123 123
- 50. Chloromonoxide Evidence for the destruction has been linked to the catalytically active Chloro monoxide ClO. &
- 51. Relationship between ClO. & O3 Ozone Layer Ozone (O3) Chlorine monoxide ClO. Chlorine monoxide ,ppb Ozone,
- 52. Thickness of Ozone Layer The thickness of the Ozone Layer is expressed in Dobson units (DU)
- 53. Other Ozone Depleters But has the reduction and removal of CFC’s solved the problem of the
- 54. Interactive Catalytic Forms Destruction: Halide Radicals destroy Ozone. The majority of Chlorine does not exit as
- 55. Interactive Catalytic Forms Formation of nonradical chlorine species. ClO. + NO2. ClONO2 Cl. + CH4 HCl
- 56. Origin of Ozone Hole The major destruction of the hole in the lower atmosphere occurs as
- 57. Ice crystal formation Nitric acid in the atmosphere forms from the reaction between OH.& NO2. Catalytically
- 58. Possible Role of CO2 “ CO2 acts as a blanket in the lower atmosphere,” says Salawitch.
- 59. Impenetrable Vortex formation The usual warming mechanism from of O + O2 O3 + Heat is
- 60. PSC’s Matter cannot readily enter this vortex and the air inside is isolated and remains cold
- 61. HCL attachment Gas phase HCl attaches to the ice particle Crystal HNO3.3H2O of HCl HCl HCl
- 62. Role of ClONO2 Ozone Layer (Radicals in PSC) Crystal HNO3.3H2O of HCl HCl HCl HCl HCl
- 63. Formation of Cl. Radicals Ozone Layer (Radicals in PSC) Crystal HNO3.3H2O of HCl HCl HCl HCl
- 64. Hole Closure ClONO2(g) also reacts with water H2O(s) + ClONO2(g) HOCl(g) +HNO3(s) HOCl + UV light
- 65. Dimer ClOOCl ClO. also builds up in the dark and this dimerizes to for a relatively
- 66. Antarctic and Arctic Vortexes Ozone Layer (PSC’s) The Antarctic vortex is more intense than the Arctic
- 67. Possible Link Ozone Layer “But PSC’s were here long before any one had the bright Idea
- 68. Further Reading Ozone Layer “The Hole Story” by G.Walker New Scientist, p24 , March 2000 Websites
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