Question

Identify the correct statements:
Statements:
A. Eddy diffusion is a dominant mixing process in the stratosphere.
B. Height of the troposphere at poles is less than that over the equator.
C. Mean free path of molecules in the mesosphere is longer than that in the troposphere.
Choose the correct answer from the options given below:

• A. (A) and (B) only
• B. (B) and (C) only
• C. (A) and (C) only
• D. (A), (B) and (C)

Hint:

Remember that atmospheric mixing mechanisms vary by altitude: the troposphere relies on turbulence and convection, while molecular diffusion becomes significant in the upper layers like the mesosphere.

Answer 1

The Correct Option is B

1. Statement A is incorrect. Eddy diffusion is not the dominant mixing process in the stratosphere. Molecular diffusion, rather than eddy diffusion, dominates at higher altitudes like the stratosphere.
2. Statement B is correct. The height of the troposphere is indeed less at the poles (approximately \( 8{-}10 \, \text{km} \)) than over the equator (approximately \( 16{-}18 \, \text{km} \)), due to differences in temperature and atmospheric dynamics.
3. Statement C is correct. The mean free path of molecules increases with altitude as the air density decreases. Hence, the mean free path in the mesosphere is longer than in the troposphere.

Thus, the correct statements are (B) and (C).