CAPF AC 2022 Q105: Geography – Oceanography
- (a) 1 only
- (b) 2 and 3 only
- (c) 1 and 3 only
- (d) 1, 2 and 3
Answer: (b) 2 and 3 only
Explanation
Jet streams and El Niño
How to think: check the direction of jet streams first.
The main jet streams blow from west to east, so they are westerly winds.
Then recall that El Niño is a warm current off Peru.
| Statement | Verdict | Fact |
|---|---|---|
| 1. Jet streams are high altitude easterly winds | Wrong | They are fast, narrow westerly winds in the upper troposphere |
| 2. El Niño is a warm ocean current | Correct | It replaces the cold Peruvian (Humboldt) current |
| 3. El Niño appears along the Peru coast | Correct | Usually around Christmas; the name means the Christ child |
One exception to know: the tropical easterly jet appears over India only in the summer monsoon months.
It does not make the general statement true.
Effect on India: El Niño years often bring a weak monsoon; La Niña years usually bring good rain.
Answer: (b) 2 and 3 only.
Why each option is right or wrong
- (a) Incorrect. Statement 1 is false; jet streams are westerly.
- (b) CORRECT. Statements 2 and 3 about El Niño are true.
- (c) Incorrect. It includes the false statement 1 and leaves out 2.
- (d) Incorrect. Statement 1 is false, so all three cannot be right.
Key point
Jet streams: narrow belts of fast westerly winds near the tropopause (subtropical and polar front jets). El Niño: warm current off Peru every 2 to 7 years, weakens the Indian monsoon. La Niña: the cold phase. Southern Oscillation: the linked pressure see-saw (ENSO).
Remember
Jet streams are westerlies; El Niño is warm, off Peru.
Common mistakes
- Accepting easterly because of the tropical easterly jet of the monsoon.
- Mixing up El Niño (warm) with La Niña (cold).
- Placing El Niño in the Atlantic instead of the eastern Pacific.
Exam tip
Educated guess: statements 2 and 3 are textbook lines about El Niño. Only (b) and (d) contain both, and the westerly jet stream that brings western disturbances to India rules out statement 1.
Sources
- NCERT Class XI Geography — India: Physical Environment, Chapter 4: Climate (jet streams, El Niño and the Indian monsoon)
- NCERT Class IX Geography — Contemporary India I, Chapter 4: Climate