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?
Explanation
The troposphere is the lowest atmospheric layer, extending from the Earth’s surface up to an average altitude of about 13 km, but its boundary varies significantly with latitude—stretching up to roughly 18 km at the equator and down to about 8 km at the poles. This structural bulge is governed by differential solar insolation: intense equatorial heating causes the surface air to expand and ascend vigorously, whereas extreme polar cooling creates dense, descending air masses.
* Statement I — Correct: The thickness of the troposphere is much greater at the equator (around 18 km) compared to the poles (around 8 km). This variation occurs because strong thermal expansion in low latitudes stretches the tropospheric column upward.
* Statement II — Correct: Intense, year-round solar heating at the equator drives powerful convectional currents that carry warm, buoyant air to great altitudes. These strong vertical updrafts push the tropopause higher, directly explaining why the tropospheric layer is thickest over equatorial zones.
Hence, Option (a) is the correct answer (Both Statement I and Statement II are correct and Statement II explains Statement I).