1. Mrs. K. S. K. College , Beed DEPT OF GEOGRAPHY. Dr. Awadhal Chanda
Mrs. K.S.K. College , Beed DEPT OF GEOGRAPHY Dr. Awadhal Chanda Assit.Professor

2. Definitions
Atmosphere: The thin envelope of gases surrounding the earth
Highly compressible
Density decreases rapidly with height
Air: A mechanical mixture of gases and aerosols

4. Vertical Structure of Atmosphere
Troposphere (surface to 8-20 km)
Upper boundary varies from about 8 km (poles in winter) to about 20 km (tropics)
Weather and climate layer
Most of atmosphere’s mass; all of its water

5. Vertical Structure of Atmosphere
Troposphere (surface to about 8-20 km)
Upper boundary varies from about 8 km (poles in winter) to about 20 km (tropics)
Weather and climate layer
Most of atmosphere’s mass; all of its water
Stratosphere (8-20 km up to about 50 km)
Ozone (O3) Layer
Temperature inversion

6. Vertical Structure (ctd.)
Mesosphere (50-80 km)
Temperature decreases with height. Why?
Thermosphere (80-? km)
Temperature inversion. Why?

7. Vertical Structure (ctd.)
Homosphere vs. Heterosphere

8. Vertical Structure (ctd.)
Homosphere vs. Heterosphere
Transition zones between layers
Tropopause
Stratopause
Mesopause

9. Defining Layers by Function – the Ozonosphere
Roughly corresponds to the stratosphere
How does the ozone layer work?
Why is there a “hole” in the ozone layer?
Why no “hole” where the pollution is produced?

10. Defining Layers by Function – the Ionosphere
Upper mesosphere + thermosphere
Produces the aurora borealis and aurora australis
D Layer – absorbs AM radio waves; disappears at night
E Layer – weakens at night
F Layer – reflects AM radio waves

11. Composition of the Air Uniform gases Nitrogen (N2) 78%, (O2) 21%,
Argon (Ar) 1%, trace gases (Neon, Helium, Methane (CH4), etc.)
Variable gases
Water Vapor (H2Ov), O3, CO2