UPSC Prelims 2024 Q13: Geography – Atmosphere & Climatology
- (a) Equatorial climate
- (b) China type climate
- (c) Humid subtropical climate
- (d) Marine West coast climate
Answer: (d) Marine West coast climate
Explanation
Climate Type Identification from Description
| Feature | Value Given | Climate Match |
|---|---|---|
| Annual temperature range | Low | Rules out continental climates (high range). Matches marine/oceanic. |
| Daily temperature range | Low | Oceanic influence moderates both annual AND diurnal range. |
| Precipitation distribution | Throughout the year (no dry season) | Rules out Mediterranean (dry summer) and Monsoon (dry season). Matches marine west coast. |
| Annual precipitation | 50-250 cm | Marine West Coast typical range. Equatorial would be > 200 cm. Steppe would be < 50 cm. |
MARINE WEST COAST CLIMATE (Cfb):
| Characteristic | Detail |
|---|---|
| Annual Temperature Range | LOW - mild year-round |
| Daily Temperature Range | LOW - ocean moderates extremes |
| Precipitation | Year-round, 50-250 cm - no dry season |
| Seasonal Pattern | Fairly uniform throughout year |
| Location | W Europe (UK, France), NW USA (Seattle), S Chile, NZ |
| Cause | Westerlies + warm ocean currents |
EQUATORIAL CLIMATE (Af):
| Characteristic | Detail |
|---|---|
| Annual Temperature Range | Very low - consistently hot |
| Daily Temperature Range | Very low - stable |
| Precipitation | Year-round but > 200 cm (much higher) |
| Seasonal Pattern | No dry season, year-round rain |
| Location | 0-10° latitude (Congo, Amazon, SE Asia) |
| Cause | ITCZ (Intertropical Convergence Zone) |
CHINA TYPE / HUMID SUBTROPICAL (Cfa):
| Characteristic | Detail |
|---|---|
| Annual Temperature Range | Moderate to HIGH - cold winters, hot summers |
| Daily Temperature Range | Moderate |
| Precipitation | Summer maximum - not uniform |
| Seasonal Pattern | Distinct seasonal variation |
| Location | 25-45°N/S (China, SE USA, Japan, Argentina) |
| Cause | Monsoons + summer convection |
MEDITERRANEAN CLIMATE (Cs):
| Characteristic | Detail |
|---|---|
| Annual Temperature Range | Moderate - warm/hot summers, mild winters |
| Daily Temperature Range | Moderate to high |
| Precipitation | DRY summer, WET winter - opposite of monsoon |
| Seasonal Pattern | Highly seasonal - dry in growing season |
| Location | 30-45°N/S (Mediterranean, California, Chile, Australia) |
| Cause | Subtropical high pressure in summer, westerlies in winter |
The description matches MARINE WEST COAST CLIMATE → Answer: Marine West Coast Climate
Answer: (d) Marine West coast climate.
Why each option is right or wrong
- (a) Incorrect. Equatorial climate has very low temperature range and year-round rainfall BUT annual precipitation exceeds 200 cm (often 200–400 cm) and temperatures are uniformly high throughout the year — doesn't match 50–250 cm range.
- (b) Incorrect. China Type (humid subtropical) has a marked seasonal temperature variation and summer-maximum rainfall pattern — not uniform year-round distribution.
- (c) Incorrect. Mediterranean climate has dry summers — rainfall is concentrated in winter months, making it seasonal, not year-round as described.
- (d) CORRECT. Marine West Coast climate (Cfb/Cfc) has low annual and daily temperature ranges, year-round precipitation (50–250 cm), and is found on western coasts between 40°–65° latitude.
Key point
Marine West Coast Climate = low annual + daily temperature range + year-round rainfall (50–250 cm). Found on western coasts: W Europe, NW USA/Canada, southern Chile, New Zealand. Moderated by ocean.
Remember
Marine West Coast climate has low annual and daily temperature ranges with year-round precipitation (50–250 cm). It is found on western coasts at 40–65° latitudes, moderated by westerlies and ocean currents.
Common mistakes
- Confusing Marine West Coast with Equatorial — both have year-round rain but equatorial has much higher temperatures and rainfall (> 200 cm) without the marine moderation effect.
- Not using precipitation amount as a differentiator — 50–250 cm rules out equatorial (too high) and rules out arid climates (too low).
- Forgetting that 'year-round precipitation' immediately eliminates Mediterranean (dry summer) and Monsoon (distinct dry season) climate types.
Exam tip
Marine West Coast (Cfb): low range + year-round rain. Western Europe (UK, France, Germany), NW USA (Seattle), S Chile, New Zealand. Caused by Westerlies + warm ocean currents. 'Cool summers, mild winters, always wet.'
Sources
- NCERT Class 11 Geography — Chapter 12: World Climate and Climate Change
- Koppen Climate Classification — Marine West Coast (Cfb)