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 2020 Exam.

Troposphere

  • 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 7 to 20 km.
  • All-weather occurs within this layer.
  • This layer has water vapor and mature particles.
  • Temperature decreases at the rate of 1 degree Celsius for every 165 m of height.
  • Tropopause separates Troposphere and Stratosphere.

Stratosphere

  • It is the second layer of the atmosphere found above the troposphere.
  • It extends up to 50 km of height.
  • 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.

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 85 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.

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 increases with height.
  • Aurora and satellites occur in this layer.

Ionosphere

  • 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.

Exosphere

  • 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

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