Based on the following statements, select the correct answer from the code given below:

(a) Western disturbances are driven by westerly winds.

(b) Western disturbances bring moisture from the Mediterranean Sea.

(c) They cause rainfall in the northwestern parts of India during the winter season.

Question

UnlockIAS · Accepted Answer

Correct — D, all three statements are correct. (a) A western disturbance is an extratropical low-pressure system that is steered from west to east by the westerlies, specifically by the subtropical westerly jet stream that sits over north India in winter. (b) These systems form over and around the Mediterranean and pick up their moisture there, adding more from the Caspian, the Black Sea and, closer to India, the Arabian Sea. (c) When they reach the western Himalaya they are forced to rise, and the result is winter rain over Punjab, Haryana, Delhi, western Uttar Pradesh and northern Rajasthan, with snow in Jammu and Kashmir, Ladakh, Himachal and Uttarakhand. The three statements are simply three stages of one chain, so nothing can be excluded.

Why the other options are wrong — (a) Rejects both the mechanism and the moisture source, though the westerly steering and the Mediterranean origin are the standard textbook description of a western disturbance.  (b) Drops statement (b). Students often doubt the Mediterranean because it feels too far away — but that region is precisely where these systems originate and take on moisture.  (c) Drops statement (a). Western disturbances travel west to east because the westerlies and the subtropical westerly jet carry them; without that steering they would never reach India.

Concept: A western disturbance is a mid-latitude (extratropical) cyclone, not a tropical one: it draws its energy from the temperature contrast along a front rather than from warm ocean water, and it is embedded in the westerly flow. Forming near the Mediterranean, it moves eastward across Iran, Afghanistan and Pakistan into north-west India, roughly between December and March, when the subtropical westerly jet has shifted south of the Himalaya. Its precipitation is the exact opposite of the monsoon in both season and direction of travel.

State PCS 2026 Q4 — Geography PYQ with Answer

State PCS 2026 Q4 — Geography PYQ with Answer