Q1. Western Disturbances originate primarily from which of the following water bodies?
(a) Arabian Sea and Bay of Bengal
(b) Mediterranean Sea, Caspian Sea and Black Sea
(c) Red Sea and Persian Gulf
(d) Indian Ocean and South China Sea
Q2. Which of the following jet streams is primarily responsible for the movement of Western Disturbances into the Indian subcontinent?
(a) Tropical Easterly Jet Stream
(b) Polar Vortex
(c) Subtropical Westerly Jet Stream
(d) Somali Jet
Q3. The local term for winter rainfall brought by Western Disturbances in NW India is:
(a) Kal Baisakhi
(b) Mawat
(c) Norwesters
(d) Aandhi
Q4. Western Disturbances are classified meteorologically as:
• (a) Tropical cyclones
• (b) Extra-tropical cyclones
• (c) Sub-tropical anticyclones
• (d) Monsoon depressions
Q5. Which of the following rabi crops benefits MOST directly from the rainfall brought by Western Disturbances?
• (a) Rice
• (b) Cotton
• (c) Wheat
• (d) Sugarcane
Answers with explanations
A1. (b) Mediterranean Sea, Caspian Sea and Black Sea Western Disturbances gather moisture from these extratropical water bodies as they travel eastward embedded in the westerly jet stream. The Arabian Sea and Bay of Bengal are sources for the Indian monsoon system, not WDs.
A2. (c) Subtropical Westerly Jet Stream The mid-latitude or subtropical westerly jet stream, flowing at altitudes of 9–13 km, transports WDs from West Asia into the Indian subcontinent through Pakistan and Afghanistan. The Tropical Easterly Jet Stream is a summer monsoon phenomenon flowing in the opposite direction.
A3. (b) Mawat Mawat is the traditional term for winter rains in Punjab, Haryana, and Rajasthan brought by WDs. Kal Baisakhi refers to pre-monsoon thunderstorms in West Bengal; Norwesters is another name for Kal Baisakhi; Aandhi refers to dust storms in Rajasthan.
A4. (b) Extra-tropical cyclones WDs derive their energy from temperature gradients between warm and cold air masses at mid-latitudes — the defining characteristic of extra-tropical cyclones. Tropical cyclones, by contrast, derive energy from warm ocean surfaces in the tropics.
A5. (c) Wheat Wheat is the rabi crop most dependent on WD-induced winter rainfall. The northwestern wheat belt of Punjab and Haryana — India’s breadbasket — depends critically on mawat for adequate moisture at the tillering and grain-filling stages.