3.3 Structure of the Atmosphere

Last updated at August 31, 2026 by

Is the atmosphere the same all the way up, or does it change as we go higher?
Layer Altitude Key Feature
Troposphere Surface–12 km All our weather happens here
Stratosphere Up to 50 km Contains the ozone layer
Mesosphere Up to 80 km Most meteors burn up here
Thermosphere 80–700 km Home to auroras and radio waves
Exosphere Outermost Very thin air fading into space

Temperature decreases with altitude only in the troposphere and mesosphere.

  • The atmosphere has a layered structure .
  • Layers are defined by changes in temperature and density .
  • Air density is highest near the Earth’s surface.
  • It decreases with altitude.
  • The five main layers are the troposphere, stratosphere, mesosphere, thermosphere and exosphere .
Fig. 3.3. The five layers of the atmosphere, from the surface up to space.
Definition — Altitude
The height of a location above mean sea level.
Usually measured in metres or feet.
The mean sea level is considered zero.
Altitude is measured from mean sea level, and the air grows thinner the higher we go.
💡 DON’T MISS OUT
Temperature decreases with altitude only in the troposphere and mesosphere . In the stratosphere and thermosphere, it actually increases instead.
Temperature decreases with altitude only in the troposphere and mesosphere — elsewhere it rises.
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