Atmospheric heating and greenhouse gases — UPSC Prelims PYQ 2024
Consider the following statements:
- Statement-I: The atmosphere is heated more by incoming solar radiation than by terrestrial radiation.
- Statement II: Carbon dioxide and other greenhouse gases in the atmosphere are good absorbers of long-wave radiation.
Which one of the following is correct in respect of the above statements?
- Both Statement-I and Statement-II are correct and Statement-II explains Statement-I
- Both Statement-I and Statement-II are correct, but Statement-II does not explain Statement-I
- Statement-I is correct, but Statement-II is incorrect
- Statement-I is incorrect, but Statement-II is correct
Explanation
Statement 1 is incorrect
- Atmosphere is mostly transparent to the incoming shortwave radiation but actively absorbs the outgoing terrestrial (longwave) radiation.
Statement 2 is correct
- Greenhouse gases in the atmosphere, such as water vapour and carbon dioxide, absorb a large portion of the Earth’s outgoing longwave infrared radiation, thereby warming the lower atmosphere. Therefore, as a mountain climber ascends in altitude, temperatures decrease—even though they are technically getting closer to the sun.
Answer: (d) Statement-I is incorrect, but Statement-II is correct; Difficulty Level: Easy
