Geography

Concepts to cover

1. Permanent and variable gases; ozone and carbon dioxide as absorbers
2. Water vapour: decreases with altitude, maximum in the warm humid tropics, least at poles and deserts
3. Dust particles: concentration in subtropical and temperate dry-wind regions
4. Troposphere: thickness greater at the equator (convection), lapse rate, tropopause
5. Stratosphere, ozone layer, mesosphere, thermosphere and ionosphere, exosphere