10 August,2010 11:02 AM IST | | Special Features
Leh's killer cloudburst that triggered torrential rains in the valley has claimed 114 lives and has left 340 others injured. CS brings you more on this phenomenon:
A cloudburst is sudden copious rainfall. It is an aggressive rainstorm falling for a short period of time limited to a small geographical area which has the capacity of creating flood conditions.
They are called 'bursts' probably because it was believed earlier that clouds were solid masses full of water. So, these violent storms were attributed to their bursting.
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. More than 2 cm of rain falls in a few minutes, which can be disastrous.
The air currents rushing upwards in a rainstorm hold up a large amount of water. If these currents suddenly cease, the entire amount of water descends on to a small area with catastrophic force and causes mass destruction. This is due to rapid condensation of the clouds.
They occur most often in desert and mountainous regions, and in interior regions of continental landmasses.
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.
The bursts bring rainfalls as high as 75 mm per hour.
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The floods in 2002 in Uttaranchal, that killed 28 people and 26 in July 2005 in Mumbai, are examples of cloud burst in India.
