Cloudbursts
2021 AUG 6
Preliminary >
Geography > Geophysical phenomenon > Geophysical phenomenon
Why in news?
- Increasing incidents of cloudbursts in Jammu and Kashmir, Himachal Pradesh and Uttarakhand are a clear evidence of climate change, experts have pointed out.
What is cloudbursts?
- A cloudburst is an intense torrential rainfall that lasts for a relatively short duration (few minutes to few hours).
- It is accompanied by hail and thunder, which is capable of creating flash floods.
- Every intense rainfall is not a cloudburst. It is a cloudburst when the amount of rainfall in a particular region exceeds 100 millimetres per hour, according to IMD
- At least 26 cloudbursts occurred in the Himalayan region from January through July 29, 2021
Why does cloudburst occur?
- Cloudburst occurs when moisture-rich air travels up a mountainous region, forming a vertical column of clouds known as Cumulonimbus clouds.
- These clouds usually cause rain, thunder and lightning. This upward movement of clouds is also known as ‘orographic lift’. Due to these unstable clouds, heavy rainfall may occur over a small area.
- The upward movement of clouds provides the required energy for a cloudburst.
- It usually happens at 1,000-2,500 metres above the sea level. The moisture is usually provided by low-level eastern winds associated with a low-pressure system over the Gangetic plains.
Cloud bursts in Himalayas:
- Oceans are warming up fast, as a result of which moisture-rich air reaches the Himalayan region. This leads to cloudburst.
- It is likely to occur more with an increase in moisture from the Indian Ocean
PRELIMS QUESTION
Consider the following statements regarding ‘cloudbursts’:
1. According to India Meteorological Department, a rainfall can be considered a cloudburst only if the amount of rainfall in a particular region exceeds 100 millimetres per hour
2. Cloudbursts in the Himalayan region usually happen in July and August.
Which of the statements given above is/are correct?
(a) 1 only
(b) 2 only
(c) Both 1 and 2
(d) Neither 1 nor 2
Answer