Question

Assertion (A): The temperature decreases with increasing altitude.

Reason (R): The lower layers of the atmosphere are denser due to the presence of CO₂ and water vapour.

Options

• Both A and R are true, and R is the correct reason for A.

• Both A and R are true, but R is not the correct reason for A.

• A is true, and R is false.

• A is false, and R is true.

Answer 1

Both A and R are true, and R is the correct reason for A.

Explanation:

Temperature decreases with increasing altitude because the atmosphere is heated from the Earth’s surface (terrestrial radiation). The lower layers of the atmosphere are denser and contain more carbon dioxide, water vapor, and other gases, which absorb more heat. As altitude increases, air becomes less dense and contains fewer heat-absorbing gases, so temperature decreases with height. Thus, the presence of denser gases in the lower atmosphere is the reason for the decrease in temperature with altitude.