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  1. 1. Chapter 21: The Atmosphere
  2. 2. <ul><li>The atmosphere is a collection of gases that gravity holds in a thin envelope around earth. </li></ul>
  3. 3. <ul><li>The troposphere are responsible for moderating the flow of energy to the earth. It extends up to 10 miles in the tropics and 5 miles in higher latitudes, and contains most of the watervapor and clouds. </li></ul><ul><li>Capping the troposphere is the tropopause, and above the tropopause is the stratosphere, a layer that increases with altitude. It increases because of ozone. </li></ul><ul><li>Beyond this stratosphere are two more layers the mesosphere and the thermosphere. </li></ul>
  4. 4. Weather is the day to day variations in temperature, air pressure, wind, humidity, and precipitation. Climate is the average temperature and precipitation in a given region. Oceans play an importante role in determining our climate, with the ability to absorb energy. The scientific study of the atmosphere, both weather and climate, is meteorology. Oceanic currents bring us the day to day changes in our weather as they move in a general pattern of west to east. Conveyor system: water masses move according to density from surface to deep oceans and back again.
  5. 5. Global Climate Change <ul><li>Warming process </li></ul><ul><li>The greenhouse effect is the rise in temperature that the Earth experiences because certain gases in the atmosphere (water vapor, carbon dioxide, nitrous oxide, and methane, for example) trap energy from the sun. </li></ul><ul><li>Global Cooling is the Planetary Albedo , the reflection of sunlight by clouds. </li></ul><ul><li>Greenhouse Gases </li></ul><ul><li>Water Vapor </li></ul><ul><li>Methane </li></ul><ul><li>Nitrous Oxide </li></ul><ul><li>CFC </li></ul>
  6. 6. Anthropogenic atmospheric warming vs. Cooling
  7. 7. It is certain that levels of CO2 and the other greenhouse gases are increasing in te troposphere as a result of human activities. Impacts of global warming Rising global temperatures are linked to two major impacts: regional climatic changes and a rise in the sea levels. This will affect rainfall and agriculture, it will become very evident in a few decades. Weather change: winters in Europe, El Niño events are becoming more frequent and intense IMPACTS IN FUTURE warming and its probable effects
  8. 8. <ul><li>Our Knowledge of the workings of the atmosphere has been appallingly poor, and one consequence of that lack of understanding is the strong possibility that UV radiation will increase in intensity all over Earth. </li></ul>Depletion of the ozone layer
  9. 9. <ul><li>On penetrating the atmosphere and being absorbed by biological tissues, UV radiation damages protein and DNA molecules at the surfaces of all living things. </li></ul>Radiation and importance of the shield
  10. 10. <ul><li>Halogens in the Atmosphere Chlorofluorocarbons </li></ul><ul><li>Replace hydroatoms </li></ul><ul><li>Gases at room temp. </li></ul><ul><li>Heat transfer fluid, plastic foams, cleaning computers parts, pressure </li></ul><ul><li>Damage ozone </li></ul><ul><li>CFCl 3 + UV -> Cl + CFCl 2 </li></ul><ul><li>Cl + O 3 -> ClO + O 2 </li></ul><ul><li>ClO + ClO -> 2 Cl + O 2 </li></ul>
  11. 11. <ul><li>The Ozone “Hole.” </li></ul><ul><li>Chlorine Reservoirs </li></ul><ul><li>Nasa Discovery </li></ul><ul><li>no “hole” yet </li></ul><ul><li>consequences: arctic air spreads over muchof the densely populated Northern Hemisphere </li></ul><ul><li>Controversy over Ozone Depletion </li></ul><ul><li>More Ozone Depletion </li></ul><ul><li>Coming to Grips with ozone Depletion </li></ul>