EARTH'S ATMOSPHERE

Atmospheric Layers

1. Troposphere- Closest to the Earth’s surface; contains most of the mass of the atmosphere; weather occurs here

   • Tropopause- that altitude at which the temperature stops decreasing (9 - 16 km above the Earth’s surface)

2. Stratosphere- the air temperature mainly increases with altitude and contains the ozone layer

   • Lower Stratosphere- temperature stays constant with altitude

   • Starting at the bottom of the ozone layer, the temperature increases as altitude increases

     • This is caused by the ozone molecules absorbing UV radiation from the Sun

   • Stratopause- ~50 km above Earth’s surface

3. Mesosphere- 50 - 85 km above Earth’s surface; air temperature decreases with altitude due to low solar radiation absorption in this layer

   • Mesopause- temperatures stop decreasing with altitude

4. Thermosphere- 85 - 600 km above Earth’s surface; extremely low density of air causes the temperature to rise; temperatures can be up to 2000 Celsius; absorbs solar radiation

   • Ionosphere is part of the thermosphere; made up of electrically charged particles - CAUSES THE AURORA BOREALIS

5. Exosphere- outermost layer of Earth’s atmosphere; 600 - 10,000+ km above Earth’s surface

   • Molecules are so far apart that they rarely collide with each other