Question

    Concerning Western disturbances, consider the following statements:

    1. These are weak tropical cyclones that originate over the Mediterranean Sea.

    2. Jet streams play an important role in driving these high-pressure systems into India.

    3. The rainfall that occurs due to these disturbances is known to be beneficial for the Rabi crops.

    Which of the above statements is/are correct?

    A 1 only Correct Answer Incorrect Answer
    B 3 only Correct Answer Incorrect Answer
    C 1 and 2 only Correct Answer Incorrect Answer
    D 1, 2 and 3 Correct Answer Incorrect Answer

    Solution

    Western disturbances are weak temperate or ExtraTropical (not tropical) frontal cyclones that originate over the Mediterranean Sea, gain moisture from the Caspian Sea and the Black Sea and cause winter rainfall in the North Western part of India. The Himalayas act as orographic barriers. The subtropical westerly jet stream drives this low pressure (cyclones cannot develop in High pressure regions as these regions are characterized by subsidence of wind) system towards the east of the Mediterranean Sea across Afghanistan, Pakistan and North West India. These storms are residual frontal cyclones that move at a height of 2000 metres from the mean sea level.

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