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?
Answer & explanation
Answer: (a) Both Statement I and Statement II are correct and Statement II explains Statement I
In the northern winter, land loses heat fast while the oceans, helped by warm currents such as the Gulf Stream and North Atlantic Drift, stay relatively warm. A given temperature is therefore found farther north over the sea and farther south over land, so the isotherms bend poleward over oceans and equatorward over continents; the warmer ocean air is the reason.
- ✓ Statement-I January isotherms swing north over the North Atlantic and south over Europe and especially the Siberian plain.
- ✓ Statement-II Oceans cool slowly and warm currents add heat, so in January the air over them is warmer than over the cold northern landmasses; this contrast is what bends the isotherms, so II explains I.
Remember · January (NH winter): isotherms bend poleward over oceans, equatorward over land; July reverses it. Deviation is sharper in the Northern Hemisphere because it has more land.
📘 Read it in NCERT: Class 11 Fundamentals of Physical Geography, Ch 8 (practise this chapter) · Class 11 Fundamentals of Physical Geography, Ch 8 (practise this chapter)
Sources
- NCERT Class 11 · Fundamentals of Physical Geography, Chapter 8 “In January the isotherms deviate to the north over the ocean and to the south over the continent. This can be seen on the North Atlantic Ocean.”
- NCERT Class 11 · Fundamentals of Physical Geography, Chapter 8 “The presence of warm ocean currents, Gulf Stream and North Atlantic drift, make the Northern Atlantic Ocean warmer and the isotherms bend towards the north. Over the land the temperature decreases sharply and the isotherms bend towards south in Europe.”
Question and answer: UPSC's official GS Paper I (2025, Series A) — paper ↗ · answer key ↗. Explanation: Minimalist IAS, checked 30 Sept 2026 (how we verify). ·