UPSC Prelims 2024 Q13: Identify the Climate Type from Its Description
Consider the following description:
1. Annual and daily range of temperatures is low.
2. Precipitation occurs throughout the year.
3. Precipitation varies between 50 cm – 250 cm.
What is this type of climate?
- Equatorial climate
- China type climate
- Humid subtropical climate
- Marine West coast climate
Answer: (d) Marine West coast climate
Statement-wise explanation
- 1: correct — In the marine west coast climate (Cfb), the ocean keeps temperatures moderate all year. NCERT (Class XI, Fundamentals of Physical Geography) gives summer temperatures of about 15–20°C and winter temperatures of about 4–10°C, and says both the annual and daily ranges are small. Equatorial and humid subtropical climates also have a small range in some respect, so this line alone does not decide the answer.
- 2: correct — Westerly winds and the cyclones they bring blow onshore through the year, so there is no dry season. In Köppen's code, the 'f' in Cfb means no dry season. Rain all year is also true of the equatorial and humid subtropical (China type) climates, so this line does not pick out one type either.
- 3: correct — NCERT says precipitation in the marine west coast climate varies greatly, from 50 cm to 250 cm. Windward mountain slopes receive the most and sheltered lowlands the least. This line settles the question. Equatorial rainfall is usually well above 200 cm, so its range would not begin at 50 cm, and NCERT puts humid subtropical rainfall at about 75–150 cm.
How to eliminate
Option logic does most of the work. The 'China type climate' and the 'humid subtropical climate' are two names for the same Köppen type, Cfa. Only one option can be correct, so if one of these were the answer the other would be too. That rules out both, which leaves the equatorial and the marine west coast climates. Statement 3 settles it. Equatorial regions are among the wettest on Earth, and their rainfall usually exceeds 200 cm, so a range that starts as low as 50 cm does not fit. A range of 50–250 cm fits the marine west coast type, which is very wet on windward slopes and much drier on the lee side. Statements 1 and 2 are traps. Several climates have rain all year and a small temperature range, so only the precipitation figure tells them apart. The fact to remember: marine west coast (Cfb) = rain all year, 50–250 cm, small annual and daily ranges.
Know more
Köppen's Group C (warm temperate) climates have a coldest month between −3°C and 18°C. The second letter gives the rainfall season (f = no dry season, s = dry summer, w = dry winter). The third gives summer heat (a = warmest month above 22°C, b = cooler summer).
| Type | Code | Location | Rainfall pattern | Key figures (NCERT) |
|---|---|---|---|---|
| Humid subtropical (China type) | Cfa | East coasts, subtropical latitudes: SE USA, S & E China, S Japan, E Australia | All year; thunderstorms in summer, frontal rain in winter | ~75–150 cm; summer ~27°C, winter 5–12°C |
| Mediterranean | Cs | West coasts, 30°–40° latitude | Winter rain, dry summer | — |
| Marine west coast (West European) | Cfb | West coasts poleward of the Mediterranean type: NW Europe, NW USA & Canada (north of California), S Chile, SE Australia, New Zealand | All year, from westerly cyclones | 50–250 cm; summer 15–20°C, winter 4–10°C |
| Monsoon-influenced subtropical | Cwa | Inland from the coast (e.g. Gangetic plain) | Dry winter | — |
Why the marine west coast climate is so mild: onshore westerlies carry ocean air inland all year. In Europe the warm North Atlantic Drift adds to this effect. Because there is no high mountain barrier near the coast in NW Europe, the oceanic influence reaches far inland. Along the coasts of the Americas, the Rockies and Andes confine it to a narrow strip.
Contrast with the equatorial (Af) climate: the equatorial climate is hot all year, with a very small annual range of temperature and heavy convectional rain, usually above 200 cm. There, the daily range of temperature is often larger than the annual range.
Pattern for similar questions: in a 'describe and identify' question, the shared features (rain all year, small range) are distractors. Look for the number, such as a rainfall range or a temperature band, and match it to the type.
NCERT Concepts to Revise
- Marine west coast climate (Cfb): One option describes this west-coast Group C type; check its rainfall range against Statement 3.
- Humid subtropical climate (Cfa): Two options name this same climate under different titles, which is the key to the option logic.
- Warm temperate climates (C): The question compares Group C types, so knowing the −3°C to 18°C coldest-month rule frames the comparison.
- Westerlies: Year-round rain in Statement 2 depends on which winds blow onshore, and westerlies shape mid-latitude west coasts.