Which Koppen climate type is described by the following characteristics?

Question

Which Koppen climate type is described by the following characteristics?

I. Average monthly temperature rarely falls below 18°C.

II. Annual rainfall exceeds 2000 mm, distributed evenly throughout the year.

III. Humid conditions support dense evergreen forests.

1. A. Aw – Tropical savanna
2. B. Af – Tropical rainforest (Correct answer)
3. C. Am – Tropical monsoon
4. D. BWh – Hot desert

Correct Answer

Option B — B

Detailed Solution & Explanation

The correct answer is Option B.

Key Points

• In the Koppen classification, 'A' denotes tropical climates where the average temperature of the coldest month is at least 18°C. The third letter distinguishes the rainfall regime:
• Af (f = feucht, meaning moist) — rain in ALL months, no real dry season, typically over 2000 mm spread evenly. This supports dense evergreen rainforest, matching all three clues.
• Am — tropical monsoon: a brief dry season, then heavy seasonal rain.
• Aw — tropical savanna: a pronounced dry WINTER, so rainfall is not evenly distributed.
• BWh — hot desert, arid; fails both the rainfall and vegetation clues.

Exam Tip

• the discriminator here is 'distributed evenly throughout the year'.
• Even distribution rules out Aw and Am immediately, since both are defined by a dry season.
• In India, Af conditions occur in parts of the Western Ghats and the Andaman & Nicobar Islands.

Additional Information

• In Köppen's system the first letter gives the broad zone: A tropical, B dry, C warm temperate, D cold, E polar; the second and third letters describe rainfall and temperature detail.
• India's principal types: Aw (tropical savanna, most of the peninsula), Amw (monsoon with short dry season, the west coast), BWh (hot desert, western Rajasthan), Cwg (Ganga plain) and E in the high Himalayas.
• The dividing line for an A climate is a coldest-month mean of 18°C.