Structure of Atmosphere (NCERT Notes for Geography)

Our atmosphere is composed of many components. But the structure of the atmosphere is a combination of various layers.

Structure of Atmosphere (UPSC Notes):- Download PDF Here

The structure of the atmosphere is represented in a pictorial form below:

Structure of the Atmosphere

There are five layers in the structure of the atmosphere depending upon temperature. These layers are:

  • Troposphere
  • Stratosphere
  • Mesosphere
  • Thermosphere
  • Exosphere

This is an important topic in the Geography syllabus for UPSC 2022 Exam.


  • It is considered as the lowest layer of Earth’s atmosphere.
  • The troposphere starts at the surface of the earth and goes up to a height of 8 kms (poles) to 18 kms (equator). The main reason of higher height at the equator is due to presence of hot convection currents that push the gases upward.
  • All kinds of weather changes occurs within this layer.
  • This layer has water vapor and mature particles.
  • Temperature decreases with increasing height of atmosphere at the rate of 1 degree Celsius for every 165 m of height. This is called Normal lapse rate.
  • Tropopause, the transitional zone, separates Troposphere and Stratosphere.


  • It is the second layer of the atmosphere found above the troposphere.
  • It extends up to a height of 50 km from the earth’s surface.
  • This layer is very dry as it contains little water vapour.
  • This layer provides some advantages for flight because it is above stormy weather and has steady, strong, horizontal winds.
  • The ozone layer is found in this layer.
  • The ozone layer absorbs UV rays and safeguards earth from harmful radiation.
  • Stratopause separates Stratosphere and Mesosphere.


  • The Mesosphere is found above the stratosphere.
  • It is the coldest of the atmospheric layers.
  • The mesosphere starts at 50 km above the surface of Earth and goes up to 80 km.
  • The temperature drops with altitude in this layer.
  • By 80 km it reaches -100 degrees Celsius.
  • Meteors burn up in this layer.
  • The upper limit is called Mesopause which separates Mesosphere and Thermosphere.


  • This layer is found above Mesopause from 80 to 400 km.
  • Radio waves that are transmitted from the earth are reflected by this layer.
  • The temperature starts increasing again with increasing height in this layer.
  • Aurora and satellites occur in this layer.


  • The lower Thermosphere is called the Ionosphere.
  • The ionosphere consists of electrically charged particles known as ions.
  • This layer is defined as the layer of the atmosphere of Earth that is ionized by cosmic and solar radiation.
  • It is positioned between 80 and 400 km above the Mesopause.


  • It is the outermost layer of the atmosphere.
  • The zone where molecules and atoms escape into space is mentioned as the exosphere.
  • It extends from the top of the thermosphere up to 10,000 km.

Structure of Atmosphere (UPSC Notes):- Download PDF Here

Also, See:

General circulation of the atmosphere
Composition of the atmosphere
Heating and Cooling of Atmosphere

Relevant Links

UPSC Mains General Studies Paper 1 Syllabus, Strategy & Structure 100 Difference between Articles
Previous Years Geography Questions in UPSC Mains General Studies Paper- 1 Topic-Wise General Studies Paper-1 Questions in UPSC Mains

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