Question

Consider the following statements regarding "Western Cyclonic Disturbances":

1. They enter the Indian subcontinent from the West during winter.

2. They are brought in with the help of the Easterly Jet Streams.

3. They cause heavy rainfall and high wind speeds in coastal Tamil Nadu and Andhra Pradesh.

Which of the statements given above is/are correct?

• A. 1 and 2 only
• B. 2 and 3 only
• C. 1 and 3 only
• D. 1, 2, and 3

Answer 1

Answer:

C. 1 and 3 only

Western Cyclonic Disturbances (WCDs) and their Impact on India

• Origin and Movement: WCDs are low-pressure systems that originate over the Mediterranean Sea and the Atlantic Ocean. They travel eastwards and typically enter the Indian subcontinent through the northwestern parts, i.e., Punjab and Haryana, during the winter months (December to February).
• Role of Jet Streams: The movement of these disturbances is facilitated by the Westerly Jet Streams, not the Easterly Jet Streams. The Westerly Jet Streams play a crucial role in steering these systems towards India.
• Impact on Rainfall: While WCDs are primarily associated with light to moderate rainfall in the northwestern plains, they can cause more significant precipitation in the northern mountainous regions, leading to snowfall in the Himalayas.
• Precipitation in Southern India: Statements mentioning heavy rainfall and high wind speeds in coastal Tamil Nadu and Andhra Pradesh due to WCDs are generally incorrect. These regions primarily receive rainfall during the Northeast Monsoon season (October to December), which is a separate phenomenon. WCDs have minimal direct impact on the weather of these southern coastal areas.
• Significance for Agriculture: The winter rainfall caused by WCDs is highly beneficial for the Rabi crops (winter crops) like wheat, barley, and gram, grown in the northwestern plains of India.
• Distinction from Tropical Cyclones: It is important to distinguish WCDs from tropical cyclones, which form over the Bay of Bengal and the Arabian Sea and affect India's eastern and western coasts, respectively, often bringing heavy rainfall and strong winds.