1. Composition of the Atmosphere

2. Carbon Dioxide Water Vapor 0-4% by volumn Variable Components of the atmosphere

3. Aerosol - fine solid or liquid particles suspended in the air (0.001 to 10 )

4. Formation of Ozone Ozone Sustaining Ozone Depletion of Ozone 10-50 km (stratosphere)

5. Ozone Depletion Ozone

6. The Ozone Hole Ozone concentration drops sharply over Antarctica

7. The Ozone Hole Polar vortex Cold air -80C 1. Polar winter leading to the formation of circumpolar winds to develop the polar vortex which isolates the air within it. 2. Cold temperatures; cold enough for the formation of Polar Stratospheric Clouds. As the vortex air is isolated, the cold temperatures persist. 3. The chlorine reservoir species HCl and ClONO2 become very active on the surface of the polar stratospheric clouds. The most important reactions are:

8. Global Ozone Recovery Predictions Protecting the atmosphere’s ozone layer An international agreement known as the Montreal Protocol on substances that deplete the Ozone Layer was concluded under the auspices of United Nations in late 1987.

9. Pressure Decreases with Altitude Atmospheric pressure P: Force F acting on unit area due to the weight of the atmosphere. Extent of the Atmosphere International System (SI) of units or Metric system

10. Temperature Thermal Structure of the Atmosphere Thermal Structure of the Atmosphere Temperature measures the average kinetic energy of molecules and atoms as they move.

11. Troposphere Height of the tropopause varies with latitude Averaged Surface temperature is 288.16K, or 15C. Decreases 6.5C per km up to 11 km (lapse rate) Nearly all weather happens in this layer Inversion: negative lapse rate. Temperature increase with height.

12. Stratosphere The temperature at first remains nearly constant to a height of about 20km, and then, increases sharply until the stratopause.

13. Mesosphere -90C (-130F) The coldest layer of the atmosphere Thermosphere Contains only a minute fraction of the air mass. The temperature rises owing to the absorption of very shortwave solar radiation by atoms of O and N.

14. Homosphere: The makeup of the air is uniform in terms of the proportions of its component of gases. (0 – 80/90 km) Heterosphere: (from lowest to highest) N2, O, He, H. (80/90 km above) Vertical Variations in Composition Ionosphere: (80/90-400km) Molecules and atoms are ionized by shortwave solar radiation into ions and electrons.

15. Aurora Borealis from AlaskaAustralis from Space Aurora results from the interaction between solar flare activity and Earth’s magnetic field. Solar flare are massive magnetic storms emitting fast-moving atomic particles (protons and electrons). As they approach the Earth, they are captured by Earth’s magnetic field, which guides them toward the magnetic poles. They impinge on the ionosphere and energize the atoms of oxygen and nitrogen molecules to cause them to emit light.

16. Structure of the Atmosphere Troposphere: Lowest 10 (mid-lat) to 16 km (tropics). Where the weather happens. Tropopause is top boundary, ~75% of the atmosphere Lapse rate: Temperature decrease with height in the Troposphere, standard = 6.5C per kilometer in the troposphere. Inversion: Negative lapse rate, temperature increases. Stratosphere: Temperature constant at about –55C then increases with height to 45-50 km where it is about –5 to 0 C. Warmed by O3 absorption (30-60 km) of solar UV. Stratopause is top boundary, ~ 99% of the atmosphere Mesosphere: Temperature decreases with height reaching < -85C. Mesopause is top boundary, above 99.9% of the atmosphere at 80-85 km. Thermosphere: Above the mesosphere. Temperature increases greatly because air absorbs sunlight, but radiates inefficiently. Boundary of Space: 100 km Ionosphere: Overlaps Meosphere and thermosphere. Reflects AM radio at night but during the day extends lower (100 km  60 km) and absorbs most AM radio energy. Ozone layer: 10-50 km, produced by sunlight breaking up oxygen Protects us from solar UV.