Cloudburst
From Wikipedia, the free encyclopedia
- For alternate uses, see Cloudburst (disambiguation).
A cloudburst is an extreme form of rainfall, sometimes mixed with hail and thunder, which normally lasts no longer than a few minutes but is capable of creating minor flood conditions.
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[edit] Etymology
They are called 'bursts' probably because it was believed earlier that clouds were solid masses full of water. These violent storms were attributed to their bursting.
There are similar names for such events in other languages. For example, in Polish the equally vague term used is "Oberwanie Chmury".
[edit] Properties
Cloudbursts descend from very high clouds, sometimes with tops above 15 kilometers. Meteorologists say the rain from a cloudburst is usually of the shower type with a fall rate equal to or greater than 100 mm (4.94 inches) per hour.[1]
During a cloudburst, more than 2 cm of rain may fall in a few minutes. When there are instances of cloudbursts, the results can be disastrous.
Rapid precipitation from cumulonimbus clouds is possible due to so called Langmuir precipitation process in which large droplets can grow rapidly by coagulating with smaller droplets which fall down slowly.
[edit] Cloudbursts in the Subcontinent
In the Indian subcontinent, a cloudburst usually occurs when a pregnant monsoon cloud drifts northwards, from the Bay of Bengal or Arabian Sea across the plains, then onto the Himalaya and bursts, bringing rainfall as high as 75 millimeters per hour.[2]
An example was the sudden cloud burst over the Indian city of Mumbai and other regions of western India, [[2005 Maharashtra floods|which occurred on 26 July 2005]]. Approximately 950mm of rainfall was recorded in Mumbai over a span of eight to ten hours; the deluge completely paralysed India's largest city and financial centre.
Cloudbursts frequently occur in Himachal Pradesh during the monsoon. The monsoon rains during July and August put a lot of water into the Himalayan soil.
[edit] World Record Cloudbursts[3]
1 minute: 1.5 inches (38.10 mm) at Barot, Guadeloupe, 26 November 1970.
5 minutes: 2.43 inches (61.72 mm) at Port Bells, Panama, 29 November 1911.
15 minutes: 7.8 inches (198.12 mm) at Plumb Point, Jamaica, 12 May 1916.
20 minutes: 8.1 inches (205.74 mm) at Curtea-de-Arges, Romania, 7 July 1947.
40 minutes: 9.25 inches (234.95 mm) at Guinea, Virginia, USA, 24 August 1906.
[edit] In News
- On August 14, 2007, at least 100 people were feared washed away in flash floods caused by cloudburst at a village near Shimla, India.[4]
- In July 2007, close to 30,000 people were displaced in Kerala after a cloudburst & flash floods following it.[5]
[edit] Notes
- ^ “What is a cloudburst?”, Rediff News, India, August 1, <http://in.rediff.com/news/2005/aug/01gi1.htm>
- ^ Cloudburst In The Subcontinent Weathernotebook.org
- ^ Heidorn, Keith C.. THE WEATHER DOCTOR.
- ^ “100 feared killed in Himachal cloudburst”, CNN IBN, India, 14 August, <http://www.ibnlive.com/news/100-feared-killed-in-himachal-cloudburst/46850-3.html>
- ^ “Kerala villagers battle nature's fury”, NDTV, India, 20 July, <http://www.ndtv.com/convergence/ndtv/story.aspx?id=NEWEN20070019592>
