Layers of the Atmosphere

Definition

The vertical structure of the Earth's atmosphere, divided into layers by how temperature changes with height: the troposphere, stratosphere, mesosphere, thermosphere, and exosphere.

Key points

• Troposphere (surface to about 8 to 18 km, lowest at the poles, highest at the equator): temperature falls with height; holds almost all weather, clouds, and water vapour; the top is the tropopause.
• Stratosphere (up to about 50 km): temperature rises with height because the ozone layer here absorbs ultraviolet radiation; it is stable, so jet aircraft cruise here.
• Mesosphere (up to about 80 km): temperature falls again and is the coldest layer; meteors burn up here.
• Thermosphere (up to about 400 km and beyond): temperature rises sharply; the ionosphere within it reflects radio waves and gives the auroras.
• Exosphere: the outermost, merging into space; satellites orbit in this region.

Why it matters for CAPF

The order of the layers, the location of the ozone layer (stratosphere) and weather (troposphere), the coldest layer (mesosphere), and the radio-reflecting ionosphere (thermosphere) are direct objective facts.

Common confusion

Troposphere (weather, temperature falls) versus stratosphere (ozone, temperature rises); the ozone layer is in the stratosphere, not the troposphere; the mesosphere is the coldest, the thermosphere the hottest.

Parent note

climatology atmosphere and winds