Question 51 from UPSC CSE 2025 - Geography

Question

Consider the following statements:
Statement I: In January, in the Northern Hemisphere, the isotherms bend equatorward while crossing the landmasses, and poleward while crossing the oceans.
Statement II: In January, the air over the oceans is warmer than that over the landmasses in the Northern Hemisphere.
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 climatic effect of land and ocean in January (Northern Hemisphere winter). Land cools faster than oceans, so landmasses are much colder, while oceans retain warmth due to high specific heat. This causes isotherms (lines of equal temperature) to bend southward (equatorward) over cold land and northward (poleward) over relatively warmer oceans. Statement II directly describes this—oceans are warmer—and provides the reason for the pattern in Statement I. Recognizing this connection confirms both statements and the explanation relationship.

Key Info: Isotherms are lines on a map connecting points of equal temperature. In the Northern Hemisphere, January is typically the coldest month. During this period, continents lose heat rapidly, making landmasses colder than nearby oceans. Oceans, with their higher heat capacity, retain more warmth. This differential leads to isotherms bending equatorward (south) when crossing cold land, and poleward (north) when crossing warmer oceans. The phenomenon is especially visible in regions like the North Atlantic, where the presence of warm currents such as the Gulf Stream and North Atlantic Drift keep the water relatively warm, bending the isotherms northwards. Over Eurasian lands, temperatures drop quickly in winter, resulting in steep temperature gradients and strong southward bends of isotherms. This geographic-climatic contrast is fundamental to understanding world temperature maps and is a classic illustration in climatology.

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 not correct

IASCODEX · Answer

Option D: Statement I is not correct, but Statement II is correct