IAS/ PCS Prelims Practice Question-5

water vapour in atmosphere

Consider the following statements with respect to water vapour in the atmosphere:

  1. Water vapour increases from poles towards the equator.
  2. Water vapour decreases with altitude.

Which of the above statements is/are correct? Choose the correct answer from the given options-

(a) 1 only

(b) 2 only

(c) 1 and 2 Both

(d) Neither 1 nor 2



  • Gases form of water present in the atmosphere is called water vapour. It is one of the most variable gaseous substances present in the atmosphere.
  • It is the source of all kinds of precipitation.
  • The amount of water vapour varies from 2 percent to 4 percent. Its maximum amount in the atmosphere could be up to 4% which is found in the warm and wet regions.
  • Water vapour reaches in the atmosphere through evaporation and transpiration.
  • Water vapour absorbs part of the incoming solar radiation (insolation) from the sun and preserves the earth’s radiated heat. It thus acts like a blanket allowing the earth neither to become too cold nor too hot.
  • Water vapour also contributes to the stability and instability in the air.
  • The amount of water vapour decreases with altitude.
  • It also decreases from the equator towards the poles


  1. Water vapour increases from poles towards equator due to higher amount of insolation received towards the equator. Hence, Statement 1 is Correct.
  2. As one goes higher in the atmosphere, the amount of water vapour decreases. Hence, Statement 2 is Correct.


Hence, Option (c)- Both 1 and 2 is the Correct answer.

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