Layers of the Atmosphere


There are four main layers to Earth’s Atmosphere:


1)   Troposphere

a)   This is the layer that touches the Earth (we live in)

b)   The temperature decreases 6.5°C every kilometer you go up.  It stops rising at 12 km.

c)   The altitude of the troposphere is from 0 km to 12-17 km.

d)   Two features are:

i)      Almost all weather exists here

ii)    Convection currents carry streams of warm air upward

e)   The Tropopause separates the Troposphere from the Stratosphere



2)   Stratosphere

a)   The temperature of the lower stratosphere remains a constant -60°C

b)   The temperature of the upper stratosphere rises to +18°C, because of the hot ozone layer.

c)   The altitude of the stratosphere is from 17-50 km.

d)   Two features are:

i)      Jet streams – horizontal movement of air-very strong winds.

ii)    Ozone Layer – Protective layer of earth – holds in heat and protects from UV rays.  Ozone smells clean and sharp – Ozone is released during lightening.

e)   The stratosphere contains the most oxygen in the atmosphere.

f)      The Stratopause separates the Stratosphere from the Mesosphere.

  • The troposphere is 10 miles deep and has 75% of the mass of the atmosphere
  • The stratosphere is 20 miles deep and has 24% of the mass of the atmosphere

This means that the lowest 30 miles of the atmosphere has 99% of the mass of the molecules! However, the atmosphere goes out to 40,000 miles. It makes sense, then, that the atmospheric molecules get farther and farther apart from each other as they go up the remaining 39,970 miles, and that is just what they do. Although there are some atmospheric molecules up here, they are scattered and occasional, not like our thick ocean of air close to the surface.

3)   Mesosphere

a)   The temperature of the Mesosphere decreases to          


b)   It is the coldest region of the atmosphere.

c)   The altitude of the mesosphere is from 50-80 km.

d)   The feature of this region is that it protects Earth from meteors by burning them up before they hit Earth. The heat is caused by friction as they travel through this layer.

e)   The mesopause is the layer that separates the mesosphere from the thermosphere.



4)   Thermosphere

a)   The temperature of the thermosphere is +2000°C.  So hot it can’t be registered on a thermometer. (It is hot because it is exposed to constant UV radiation from the Sun.

b)   It is the hottest region of the atmosphere.

c)   It is broken into two smaller regions:


i)      Ionosphere

(1)     The altitude of the ionosphere is from 80-550 km.

(2)     Ions are present here (charged particles)

(3)     Responsible for radio communication


ii)    Exosphere

(1)     The altitude of the exosphere is from 550-3200 km.

(2)     Air so thin there is great visibility.

(3)     Satellites orbit there – to transmit television and telephone communication.