10 4. Layers of the atmosphere
- The atmosphere is divided into layers according to the way temperature changes with height (see the temperature graph in the book: falls, rises, falls, rises).
- From the Earth's surface upward:
1Troposphere
Approximate height
- 0 – 10 km (≈ 11 km at the tropopause)
Temperature trend
- decreases with height (6.5 °C/km)
Key features
- weather, life, densest layer
2Tropopause
Approximate height
- ≈ 10–11 km
Temperature trend
- constant
Key features
- boundary
3Stratosphere
Approximate height
- ≈ 10 – 50 km
Temperature trend
- constant to 20 km, then increases
Key features
- ozone layer; stable air; aircraft
4Mesosphere
Approximate height
- 50 – 80 km
Temperature trend
- decreases to about −93 °C
Key features
- coldest layer; meteors burn
5Thermosphere
Approximate height
- 80 – 700 km
Temperature trend
- increases to over 2000 °C
Key features
- contains the ionosphere; aurora
6Exosphere
Approximate height
- 700 – 1000 km
Temperature trend
- very high
Key features
- outer edge; satellites; escape of gases