Consider the following statements regarding water vapour in the atmosphere: 1. It is a variable gas that increases with altitude. 2. It accounts for less than one % of the air by volume in the dry and cold polar regions. 3. It absorbs parts of the insolation from the sun and preserves the earth’s radiated heat. Which of the statements given above is/are correct?

The correct option is 2 and 3 only. Explanation Water vapour is a variable gas in the atmosphere that plays a critical role in the hydrological cycle and the Earth's heat budget. Its concentration varies significantly with latitude and altitude. - Statement 1 is Incorrect: Water vapour is a variable gas that decreases with altitude, not increases. The concentration is highest near the Earth's surface, with nearly 90 % of the total water vapour found within a height of 5 km from the surface. - Statement 2 is Correct: The concentration of water vapour decreases from the equator towards the poles. In warm and wet tropics, it may account for up to four % of the air by volume, whereas in the dry and cold polar regions, it constitutes less than one % of the air. - Statement 3 is Correct: Water vapour acts as a greenhouse gas. It absorbs a portion of the incoming solar radiation (insolation) and traps the Earth's radiated heat (terrestrial radiation). This "blanket" effect prevents the Earth from becoming too cold or too hot. Key Takeaway: Water vapour concentration decreases with an increase in altitude and latitude. It is a primary greenhouse gas that regulates the Earth's temperature by absorbing both insolation and terrestrial radiation.

NCERT Class 11 Geography — Chapter 1: Composition and Structure of Atmosphere

mcqmedium

Consider the following statements regarding water vapour in the atmosphere:

It is a variable gas that increases with altitude.
It accounts for less than one % of the air by volume in the dry and cold polar regions.
It absorbs parts of the insolation from the sun and preserves the earth’s radiated heat.

Which of the statements given above is/are correct?

Official previous-year question

Verified 1 Aug 2026.

Options

A1 and 2 only
B2 only
C1, 2 and 3
D2 and 3 only

Did you get this right?

Solution

The correct option is 2 and 3 only.

Explanation

Water vapour is a variable gas in the atmosphere that plays a critical role in the hydrological cycle and the Earth's heat budget. Its concentration varies significantly with latitude and altitude.

Statement 1 is Incorrect: Water vapour is a variable gas that decreases with altitude, not increases. The concentration is highest near the Earth's surface, with nearly 90 % of the total water vapour found within a height of 5 km from the surface.
Statement 2 is Correct: The concentration of water vapour decreases from the equator towards the poles. In warm and wet tropics, it may account for up to four % of the air by volume, whereas in the dry and cold polar regions, it constitutes less than one % of the air.
Statement 3 is Correct: Water vapour acts as a greenhouse gas. It absorbs a portion of the incoming solar radiation (insolation) and traps the Earth's radiated heat (terrestrial radiation). This "blanket" effect prevents the Earth from becoming too cold or too hot.

Key Takeaway: Water vapour concentration decreases with an increase in altitude and latitude. It is a primary greenhouse gas that regulates the Earth's temperature by absorbing both insolation and terrestrial radiation.

Your note

More from Chapter 1: Composition and Structure of Atmosphere

Consider the following statements regarding the composition of the atmosphere: 1. The proportion of gases remains constant up to the highest layers of the atmosphere. 2. Nitrogen is the most abundant gas in the atmosphere. 3. Nitrogen and Oxygen make up the bulk of the atmosphere. Which of the statements given above is/are correct?

easy

Which of the following is the main reason for the rising volume of carbon dioxide in the atmosphere?

easy

With reference to the composition of the atmosphere, consider the following statements: 1. Oxygen is found in substantial quantities at heights above 120 km from the earth's surface. 2. Carbon dioxide is transparent to incoming solar radiation but opaque to outgoing terrestrial radiation. 3. Carbon dioxide and water vapour are found in uniform concentration up to the exosphere. Which of the statements given above is/are correct?

medium

Which one of the following is the most likely reason for the higher concentration of dust particles in subtropical and temperate regions compared to equatorial regions?

easy

In the context of the structure of the atmosphere, consider the following statements regarding the Troposphere: 1. The temperature in this layer increases with height. 2. Its thickness is greatest at the equator and least at the poles. 3. It is devoid of dust particles and water vapour. Which of the statements given above is/are correct?

easy

Keep practising Chapter 1: Composition and Structure of Atmosphere

Work through every question from this NCERT chapter.

Browse all NCERT Class 11 Geography chapters

The correct option is 2 and 3 only.

Explanation

Water vapour is a variable gas in the atmosphere that plays a critical role in the hydrological cycle and the Earth's heat budget. Its concentration varies significantly with latitude and altitude.

Statement 1 is Incorrect: Water vapour is a variable gas that decreases with altitude, not increases. The concentration is highest near the Earth's surface, with nearly 90 % of the total water vapour found within a height of 5 km from the surface.
Statement 2 is Correct: The concentration of water vapour decreases from the equator towards the poles. In warm and wet tropics, it may account for up to four % of the air by volume, whereas in the dry and cold polar regions, it constitutes less than one % of the air.
Statement 3 is Correct: Water vapour acts as a greenhouse gas. It absorbs a portion of the incoming solar radiation (insolation) and traps the Earth's radiated heat (terrestrial radiation). This "blanket" effect prevents the Earth from becoming too cold or too hot.