- The atmosphere can be heated upwards only from the Earth’s surface.
- There is more moisture in the upper atmosphere.
- The air is less dense in the upper atmosphere.
Select the correct answer using the code given below:
(a) 1 only
(b) 2 and 3 only
(c) 1 and 3 only
(d) 1, 2 and 3
Answer: (c)
Option (c) is correct: In the troposphere, temperature decreases as altitude increases primarily because Earth’s atmosphere is heated upward from the lowest level. The atmosphere is warmed from the ground up, and since the air is at its most dense near the surface of the Earth, the air near the surface is going to be able to remain much more heat than the air at higher elevations due to the increased amounts of air molecules; higher elevations have fewer air molecules and consequently cannot remain much heated. Simply putting, as elevation increases, there is less air above thus the pressure decreases. As the pressure decreases, air molecules spread out further (i.e., air expands) and the temperature decreases. Temperature decreases with altitude only in the troposphere and the mesosphere.
Elimination Technique: Statement 2 and 3 are contradictory and can not be correct simultaneously. In the upper atmosphere moisture is less. So, by eliminating the statement 2 we can get the answer C.
