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?

Answer: (a) Both are correct and Statement-II explains Statement-I

The troposphere is about 18 km thick at the equator and 8 km at the poles, because strong convection carries heat very high at the equator.

The idea

The troposphere is the lowest atmospheric layer, where most weather occurs. Heating makes air expand and encourages upward movement. Strong tropical convection carries heat higher, raising the boundary called the tropopause. Its height changes with latitude, season and weather.

Strong surface heating → Warm air expands → Buoyant air rises → Convection carries heat upward → Tropical tropopause stands higher

Why the others are wrong

(b) Treats convection as a separate fact. It is the mechanism: rising currents carry heat high, so the layer is thicker.

(c) Treats II as wrong, perhaps thinking the poles have a thicker layer of dense air. Thickness follows how high convection lifts heat, which is strongest at the equator.

(d) Treats I as wrong. The troposphere is ~18 km at the equator vs ~8 km at the poles.

The trap

Some expect the poles to have “more air” because air is dense there. Thickness follows how high heat is carried, not density.

Also know

Temperature generally falls upward through the troposphere, but rises through much of the stratosphere because ozone absorbs ultraviolet radiation. Most water vapour and clouds are in the troposphere. The mesosphere above the stratosphere is where many meteors burn up. A temperature inversion is a local reversal of the usual downward-to-upward cooling.