UPSC CSE Prelims
Question 58
Consider the following statements :
- Without the atmosphere, temperature would be well below freezing point everywhere on the Earth's surface.
- Heat absorbed and trapped by the atmosphere maintains our planet's average temperature.
- Atmosphere's gases, like carbon dioxide, are particularly good at absorbing and trapping radiation.
Which of the statements given above are correct?
View correct answer and explanation
Correct answer: C
Correct Option: C (I, II and III)
Explanation: The natural greenhouse effect keeps Earth's mean temperature far warmer than it would be without an atmosphere. Atmospheric greenhouse gases absorb and re-emit outgoing infrared radiation, moderating surface temperatures.
Statement / Pair / Item-wise Analysis:
I: Treated as true in the examination's global-average sense (without a greenhouse atmosphere Earth's mean temperature would be below freezing; 'everywhere' is an imprecise absolute).
II: True-the atmosphere retains heat.
III: True-CO₂ and other greenhouse gases absorb infrared radiation.
Option-wise Analysis:
A. Incorrect-omits II which the answer requires.
B. Incorrect-omits III which the answer requires.
C. Correct-this matches the facts and the item-wise assessment above.
D. Incorrect-omits I which the answer requires.