Q. 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?
(a) Both Statement-I and Statement-II are correct and Statement-II explains Statement-I
(b) Both Statement-I and Statement-II are correct, but Statement-II does not explain Statement-I
(c) Statement-I is correct, but Statement-II is incorrect
(d) Statement-I is incorrect, but Statement-II is correct
Correct answer: (d) Statement-I is incorrect, but Statement-II is correct
Question from UPSC Prelims 2024 GS Paper
Explanation:
Statement-I: The atmosphere is heated more by incoming solar radiation than by terrestrial radiation.
This statement is incorrect. The atmosphere is actually heated more by terrestrial radiation than by direct solar radiation. Here’s why:
1. Most of the incoming solar radiation (shortwave radiation) passes through the atmosphere without being absorbed.
2. The Earth’s surface absorbs this solar radiation and heats up.
3. The warm surface then emits longwave (infrared) radiation.
4. This terrestrial longwave radiation is more readily absorbed by the atmosphere, particularly by greenhouse gases.
Statement-II: Carbon dioxide and other greenhouse gases in the atmosphere are good absorbers of long wave radiation.
This statement is correct. Greenhouse gases, including carbon dioxide, water vapor, methane, and others, are indeed effective absorbers of longwave (infrared) radiation. This is the fundamental principle behind the greenhouse effect.