This article covers every important point you need to remember about our Atmosphere for clearing IAS Exam

Introduction

  • Our Earth comprises of Land (Lithosphere), Water (Hydrosphere) and Air (Atmosphere).
  • The atmosphere is a set of layer of gases that surrounds our planet.
  • Atmosphere is held in its place by the gravity of Earth.
  • These layers of gases extend several thousand kilometres from the Earth’s surface.
  • Air exerts pressure on the earth’s surface by virtue of its weight. This pressure is known as Atmospheric Pressure. The atmospheric pressure at sea level is 1034 gm per square kilometre.

Role of the Atmosphere

  • The atmosphere contains several gases such as Oxygen, Nitrogen, Carbon dioxide etc.
  • Plants survive on Carbon dioxide and humans and other living organisms consume Oxygen for their survival. Thus the atmosphere supplies these life-giving gases.
  • Atmosphere absorbs the solar radiations of high frequencies and prevents the earth from becoming too hot. Thus, atmosphere regulates the temperature essential for life on the Earth.
  • Ozone layer present in the atmosphere absorbs harmful ultraviolet radiations coming from the sun.
  • Atmosphere is also responsible for dealing with extraterrestrial objects such as Meteors. These Meteors are burnt up by the atmosphere due to friction before they reach Earth’s surface.
  • The atmosphere is the main regulator of climate at any place. This climate is further responsible for number of natural processes like plant growth, soil formation, agriculture, human settlement etc.

Composition of Atmosphere

  • Atmosphere is a mixture of different types of gases.
  • Nitrogen, Oxygen, Argon, Carbon dioxide, Neon etc combines to form atmosphere.
  • Nitrogen and Oxygen are two main gases which make up 99% of the atmosphere.
  • Carbon dioxide is found up to 20 km above the earth whereas Oxygen and Nitrogen are found up to 100 km above the earth.
  • Percentage wise composition of gases in atmosphere:

    -Nitrogen: 78%
    -Oxygen: 21%
    -Argon:  0.93%
    -Carbon dioxide: 0.03%
    -Neon: 0.0018%
    -Helium: 0.0005%
    -Krypton: 0.001%
    -Hydrogen: 0.00005%
    -Ozone: 0.00006%

  • Nitrogen, Oxygen, Hydrogen and Argon are permanent gases whereas Carbon dioxide, Ozone, Water Vapors etc. are variable gases because there quantities varies from region to region.
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