Question

Q11. Consider the following statements about Dust storms and Thunderstorms:

1. Thunderstorms occur when atmosphere has moisture and dust storms take place when moisture is not present.

2. Such events take place due to local instability arising out of deviation from normal temperature difference between upper and lower atmosphere.

Which of the above statements are correct?

• A. a) 1 only
• B. b) 2 only
• C. c) Both 1 and 2
• D. d) Neither 1 nor 2

Answer 1

The correct option is C

c) Both 1 and 2

• Rainstorms (thunderstroms) and duststorms arise from similar meteorological conditions. They are almost always preceded and caused by spell of intense heat.
• Thunderstorms occur when atmosphere has moisture and duststorms take place when moisture is not present.
• Such events take place due to local instability arising out of deviation from normal temperature difference between upper and lower atmosphere. Thus, these events themselves are very localised both in time and space.
• In recent rainstorms and duststorms cases in Uttar Pradesh and Rajasthan, moist easterly winds from Bay of Bengal reached up to Himachal Pradesh colluded with dry winds from north-westerly direction.
• The two systems destabilised equilibrium temperature difference between upper and lower layers of atmosphere, leading to conducive conditions for thunderstorm and duststroms.
• The final trigger, however, is development of largescale air-circulation system. Many parts of India witness build-up of surface heat during this time of year. The places that were hit by recent storms had seen heat-wave like conditions.