Q49.
Normally, the temperature decreases with the increase in height from the Earth's surface, because 1. The atmosphere can be heated upwards only from the Earth's surface 2. There is more moisture in the upper atmosphere. 3. The air is less dense in the upper atmosphere. Select the correct answer using the codes given below:
Answer
C
Explanation
Temperature decreases with altitude because: (1) The atmosphere is warmed from below (from Earth's surface) — the Earth absorbs solar radiation and re-radiates it as longwave radiation which heats the atmosphere from the ground up. (3) Air is less dense at higher altitudes — fewer air molecules mean less ability to retain heat. Statement 2 is incorrect — there is actually more moisture (water vapour) in lower atmosphere, not upper. Moisture helps retain heat, and its absence at higher altitudes also contributes to cooling.