Question 8 from UPSC CSE 2024 - Geograph y

Question

Consider the following statements:
Statement-I: Thickness of the troposphere at the equator is much greater as compared to poles.
Statement-II: At the equator, heat is transported to great heights by strong convectional currents.
Which one of the following is correct in respect of the above statements?

IASCODEX · Accepted Answer

Correct Option: A. Both Statement-I and Statement-II are correct and Statement-II explains Statement-I

Strategy: Focus on the comparative keyword 'thickness' of the troposphere at different latitudes. Recall that at the equator, intense solar heating creates stronger upward convection currents, which causes the troposphere to extend higher. Statement-II directly explains the reason for Statement-I. Both statements are correct, and Statement-II provides the scientific mechanism for Statement-I, making option A correct.

Key Info: The troposphere is the lowest atmospheric layer, extending from Earth's surface to the tropopause. Its thickness varies with latitude: about 8 km at the poles, 13 km on average, and approximately 16–18 km at the equator. The increase at the equator is due to intense heating, causing vigorous convection—rising warm air transports energy and moisture to higher altitudes, expanding the vertical extent of the troposphere. This layer contains almost all atmospheric water vapour and is the site for weather phenomena like clouds, rainfall, and storms. The temperature in the troposphere generally decreases with altitude at a rate called the environmental lapse rate (approximately 6.5°C per 1,000 m). The upper boundary, the tropopause, marks a temperature inversion and has lower temperatures over the equator (around –80°C) than at the poles (about –45°C). The process of convection is most active at the equator, driven by maximal insolation, and is limited at higher latitudes due to reduced heating.

IASCODEX · Answer

Option B: Both Statement-I and Statement-II are correct, but Statement-II does not explain Statement-I

IASCODEX · Answer

Option C: Statement-I is correct, but Statement-II is incorrect

IASCODEX · Answer

Option D: Statement-I is incorrect, but Statement-II is correct