Q27 (IAS/2025) Geography › World Physical Geography › Atmospheric heat balance Answer Verified

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?

Both Statement I and Statement II are correct and Statement II explains Statement I

Both Statement I and Statement II are correct but Statement II does not explain Statement I

Statement I is correct but Statement II is not correct

Statement I is not correct but Statement II is correct

Result

Your answer: — · Correct: A

Explanation

Both statements are correct, and Statement II correctly explains Statement I.

In January, the isotherms deviate to the north over the ocean and to the south over the continent.[3] This confirms Statement I – isotherms bend poleward (northward) over oceans and equatorward (southward) over landmasses in the Northern Hemisphere during January.

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.[1] Over the land the temperature decreases sharply and the isotherms bend towards south in Europe.[1] This demonstrates that oceans are warmer than landmasses in January, confirming Statement II.

The causal relationship is clear: The isotherms deviate equatorward over the continents (due to continentality) as the cold polar winds are able to penetrate southwards into the interiors.[4] The warmer ocean temperatures cause isotherms to bend poleward over oceans, while colder continental temperatures cause them to bend equatorward over land. Therefore, Statement II (warmer oceans) directly explains the isotherm pattern described in Statement I.

Sources

[1] FUNDAMENTALS OF PHYSICAL GEOGRAPHY, Geography Class XI (NCERT 2025 ed.) > Chapter 8: Solar Radiation, Heat Balance and Temperature > Distribution of Temperature > p. 71
[2] FUNDAMENTALS OF PHYSICAL GEOGRAPHY, Geography Class XI (NCERT 2025 ed.) > Chapter 8: Solar Radiation, Heat Balance and Temperature > Distribution of Temperature > p. 71
[3] FUNDAMENTALS OF PHYSICAL GEOGRAPHY, Geography Class XI (NCERT 2025 ed.) > Chapter 8: Solar Radiation, Heat Balance and Temperature > Distribution of Temperature > p. 71
[4] Physical Geography by PMF IAS, Manjunath Thamminidi, PMF IAS (1st ed.) > Chapter 21: Horizontal Distribution of Temperature > Northern Hemisphere > p. 290

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Don’t just practise – reverse-engineer the question. This panel shows where this PYQ came from (books / web), how the examiner broke it into hidden statements, and which nearby micro-concepts you were supposed to learn from it. Treat it like an autopsy of the question: what might have triggered it, which exact lines in the book matter, and what linked ideas you should carry forward to future questions.

Q. Consider the following statements : Statement I : In January, in the Northern Hemisphere, the isotherms bend equatorward while crossing t…

At a glance

Origin: From standard books Fairness: High fairness Books / CA: 10/10 · 0/10

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This is a classic 'NCERT-reward' question. It tests the fundamental concept of differential heating of land and water directly from the 'Distribution of Temperature' section in Class XI NCERT. If you analyzed the January isotherm map (Fig 8.1) in the book, this was a free hit.

How this question is built

This question can be broken into the following sub-statements. Tap a statement sentence to jump into its detailed analysis.

Statement 1: In January in the Northern Hemisphere, do isotherms bend equatorward while crossing landmasses and poleward while crossing oceans?
Statement 2: In January in the Northern Hemisphere, is the air over the oceans warmer than the air over the landmasses?
Statement 3: In the Northern Hemisphere in January, is the isotherm pattern of bending equatorward over land and poleward over oceans explained by the oceans being warmer than the land?

Statement 1

In January in the Northern Hemisphere, do isotherms bend equatorward while crossing landmasses and poleward while crossing oceans?

Origin: Direct from books Fairness: Straightforward Book-answerable

From standard books

FUNDAMENTALS OF PHYSICAL GEOGRAPHY, Geography Class XI (NCERT 2025 ed.) > Chapter 8: Solar Radiation, Heat Balance and Temperature > Distribution of Temperature > p. 71

Presence: 5/5

“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. 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. It is much pronounced in the Siberian plain. The mean January temperature along 60° E longitude is minus 20° C both at 80° N and 50 N latitudes. The mean monthly temperature for January is over 27° C, in equatorial oceans over 24° C in the tropics and 2° C - 0° C in the middle latitudes and –18° C to –48° C in the Eurasian continental interior.”

Why this source?

Explicitly states that in January isotherms deviate north over oceans and south over continents (i.e., poleward over oceans, equatorward over land).
Gives the North Atlantic/Gulf Stream example showing warm ocean currents cause poleward bending of isotherms.
Provides continental examples (Europe, Siberian plain) where rapid land cooling causes equatorward bending.

Physical Geography by PMF IAS, Manjunath Thamminidi, PMF IAS (1st ed.) > Chapter 21: Horizontal Distribution of Temperature > Northern Hemisphere > p. 290

Presence: 5/5

“• The isotherms are closer on the eastern margins as the temperature gradient is high because of the less moderating effect of the oceans (westerlies flow from west to east).• The isotherms deviate to the north over the ocean. For example, the presence of warm Gulf Stream and North Atlantic drift make the Northern Atlantic warmer and the isotherms show a poleward shift indicating that the currents are able to carry high temperatures poleward.• The isotherms deviate equatorward over the continents (due to continentality) as the cold polar winds are able to penetrate southwards into the interiors.• Lowest temperatures are recorded over northern Siberia and Greenland (due to continentality). • During July, it is summer in the northern hemisphere and winter in the southern hemisphere.”

Why this source?

Directly asserts isotherms deviate to the north over the ocean and equatorward over the continents.
Explains mechanism: warm currents carry heat poleward over oceans; continentality allows cold polar winds to penetrate southward over land.

Statement analysis

This statement analysis shows book citations, web sources and indirect clues. The first statement (S1) is open for preview.

Statement analysis

This statement analysis shows book citations, web sources and indirect clues. The first statement (S1) is open for preview.

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SIMILAR QUESTIONS

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