Composition and Structure of Atmosphere

Composition and Structure of Atmosphere – Class 11

Composition and Structure of Atmosphere

  • About 78.08% of atmospheric gasses are Nitrogen (N2).
  • The amount of Oxygen (O2) in atmosphere is 20.95%.
  • Amount of Helium (He) in atmosphere is 0.0005%.
  • The amount of Hydrogen (H2) in atmosphere is 0.00005%.
  • 99% of the total atmospheric mass lies within 32 kilometers above the earth surface.
Q. Discuss about different layers of the atmosphere with proper explanation.

Answer: There are generally five layers of the atmosphere. Troposphere, stratosphere, mesosphere, ionosphere/thermosphere and exosphere.

Troposphere: Several characteristics of this layers are –
  • This is the lower most part of the atmosphere extend up to average 13 km. Generally this layer in the tropical region extends up to 18 km and about 5 km in the polar region. 
  • All the atmospheric phenomenon like cloud, rainfall, dust particles and moisture content etc. are present in this layer.
  • In this layer temperature gradually decrease with the increasing of height at the rate of 1 degree per 165 meters.
  • Temperature of the upper part of the atmosphere is about minus 80 degree (-80º).
  • This layer is divided from the stratosphere with a constant temperature zone, known as tropopause.
  • This layer is important for different kinds of weather phenomenon.
Stratosphere: This layer extends up to 50 km from the surface of the earth. Main characteristics of this layer are as follows:
  • This layer is very significant for the human beings. Because in this layer ozone (O3) layer protect our all living beings on the earth from the dangerous ultra-violet rays of the sun.
  • In this layer temperature gradually decrease with the increasing height.
  • Generally all Aeroplanes travel through this layer because, this layer is free from any kind of atmospheric disturbances.
  • This layer separates from the mesosphere by stratopause.
Mesosphere: This is the coolest layer of the atmosphere. Other characteristics are as follows:
  • This layer is extends up to 80 km above the surface.
  • The upper most part of this layer contains about minus 100 degree of temperature.
  • This layer is important because here all meteoroids burns up before reaching to the surface of the earth.
  • This layer is separates from ionosphere by another constant layer known as mesopause.
Ionosphere:
  • This layer extends between the height of 80 km to 400 km.
  • This layer is very much significant for the modern society. Because, this layer helps to transmit all kinds of radio waves and we are enable to connect each other using different devices like mobile, television, internet etc.
  • Here temperature increase rapidly with the increasing of height.

Above the layer – ionosphere is called as exosphere. This layer is the upper most part of the atmosphere. Maximum atmospheric elements are not present in this layer. (Composition and Structure of Atmosphere) Read more..

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