Climatology — Practice Questions
UPSC Prelims-pattern practice questions on climatology — pressure belts, westerlies, Mediterranean climate, tropical and temperate cyclones, and rainfall types.
Questions
These are original UPSC-pattern practice questions. Attempt each one before revealing the answer.
Which of the following pressure belts are thermally induced?
- Equatorial low-pressure belt
- Subtropical high-pressure belt
- Subpolar low-pressure belt
- Polar high-pressure belt
Select the correct answer using the code given below.
Solution
- Equatorial low — thermal: intense heating makes air expand and rise.
- Polar high — thermal: intense cold makes air contract and sink.
- Subtropical high — dynamic: air that rose at the Equator descends around 30° in the Hadley circulation.
- Subpolar low — dynamic: associated with the Earth’s rotation and the convergence of the westerlies and polar easterlies.
Answer: B
The term “Roaring Forties” refers to:
Solution
The Southern Hemisphere is mostly ocean between 40° and 60° S, so the westerlies meet little friction and blow strongly and steadily. Sailors named the belts the Roaring Forties, Furious Fifties and Shrieking Sixties.
Trade winds blow between the subtropical highs (~30°) and the Equator, so option B is wrong on both direction and latitude.
Answer: A
Consider the following statements about the Mediterranean type of climate:
- Most of the rainfall is received in winter.
- It is found on the western margins of continents roughly between 30° and 40° latitude.
- Its rainfall is brought mainly by the trade winds.
Which of the statements given above are correct?
Solution
- Statements 1 and 2 — correct. Mediterranean climates occur around the Mediterranean Sea, in California, central Chile, the south-western tip of Africa and south-western Australia.
- Statement 3 — wrong. In winter the pressure belts shift towards the Equator, bringing these regions under the westerlies and their temperate cyclones. In summer, the subtropical high and offshore trade winds keep them dry.
Answer: C
Consider the following statements:
- Temperate cyclones have well-developed fronts.
- Tropical cyclones draw their energy mainly from the latent heat of condensation.
- Tropical cyclones generally intensify after landfall.
- Temperate cyclones generally move from west to east.
How many of the above statements are correct?
Solution
- 1 — correct. Temperate cyclones form where warm and cold air masses meet along the polar front, with warm, cold and occluded fronts.
- 2 — correct. Tropical cyclones are heat engines powered by latent heat released over warm seas.
- 3 — wrong. After landfall, a tropical cyclone loses its supply of warm, moist air and friction increases, so it weakens.
- 4 — correct. Temperate cyclones are carried by the westerlies.
So three statements are correct.
Answer: C
During the south-west monsoon, Mumbai on the coast receives far more rainfall than Pune, which lies on the leeward side of the Western Ghats. This is best explained by:
Solution
Moist south-west monsoon winds are forced up the windward slopes of the Western Ghats; the rising air cools and sheds heavy orographic rain. Having crossed the crest, the air descends on the leeward side, warms and dries — the rain-shadow effect that leaves Pune and much of the Deccan comparatively dry.
Convectional rain depends on local surface heating; cyclonic and frontal rain depend on weather systems. None explains a windward–leeward contrast.
Answer: D
Mains
Why are most of the world’s major hot deserts located on the western margins of continents between about 15° and 30° latitude? Explain with examples.
Solution
Introduction: The Sahara, Arabian, Thar, Kalahari–Namib, Atacama, Sonoran and the great Australian deserts all lie broadly between 15° and 30° N or S, and many extend to the western coasts of continents. Their location results from planetary pressure and wind systems combined with ocean currents.
Body:
- Subtropical high-pressure belt: air descending from the Hadley cell warms adiabatically and dries; descending air suppresses cloud formation, giving clear skies and very little rain.
- Trade winds: blow from the east; by the time they reach the western sides of continents they have lost most moisture over land, and on west coasts they blow offshore.
- Cold ocean currents on west coasts: Canary (Sahara), Benguela (Namib), Humboldt or Peru (Atacama), California (Sonoran–Mojave region), West Australian (Australian deserts) — they cool the lower air, create a stable inversion and produce fog but not rain.
- Rain-shadow and continentality: mountains (the Andes for Patagonia, the Rockies for the Great Basin) and distance from the sea add to aridity in some deserts.
- Contrast: the east sides of continents at the same latitudes are wetter, because onshore trades and warm currents (Gulf Stream, Brazil, Agulhas, East Australian) bring moisture.
Conclusion: Hot deserts are a predictable outcome of the general circulation: subsiding air, offshore trades and cold currents together make the western subtropical margins the driest places on Earth.