What Is a Cloudburst

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  • Topic: Water, Cloud, Rain
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  • Published : August 2, 2010
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What is a cloudburst?

A cloudburst is sudden copious rainfall. It is a sudden aggressive rainstorm falling for a short period of time limited to a small geographical area.

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.

Generally cloudbursts are associated with thunderstorms. 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 all of a sudden and causes mass destruction. This is due to a rapid condensation of the clouds.

They occur most often in desert and mountainous regions, and in interior regions of continental landmasses.

During a cloudburst, more than 2 cm of rain may fall in a few minutes. 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.

One of the major disasters from a cloudburst in India [ Images ] occurred in 2002 in Uttaranchal. Some 28 people died when villages like Marwari, Kotsisham, Matgoan and Agonda were hit by sudden cloudbursts.

Cloudbursts frequently occur in Himachal Pradesh [ Images ] during the monsoon.

Cloud burst is actually a situation when the intermolecular forces between the H2O molecules get very high due to the rapid decrease in the temperature or excess of electrostatic induction in the clouds causing the lighting to remain inside the cloud only, which causes hyperactive energy inside the cloud. The water molecules get denser and denser and get condensed but do not leave the cloud due to excess of electroforces. As the water concentration get higher and higher and so the weigh gets heavier the water no longer is able to maintain force with the clouds and so they fall and it precipitates. As the water content is so high and also(as per the law of conservation of enrgy) the electricity remains in it, the clous seems to be bursted.

A cloud burst results literally when rain and wind burst from a cloud. Often as a storm approaches, the first strong rain falling from the storm front entrains masses of air moving down to the ground causing wind gusts and bending trees, etc. It is often a warning that the heavy rain will soon follow.

Cloudbursts or downpours have no strict meteorological definition. The term usually signifies a sudden, heavy fall of rain over a short period of time. Some observers suggest a rainfall rate in excess of 25 millimetres per hour (1 inch per hour) constitutes a downpour, but when you're drenched, the amount does not matter all that much. We do know that most cloudbursts come from convective, cumulonimbus clouds that form thunderstorms and that the air is generally rather warm in order to contain the amount of moisture needed for a heavy downpour. Besides providing the proper conditions to spawn large quantities of liquid water drops, cumulonimbus clouds have regions of strong updrafts which hold raindrops aloft en masse and can produce the largest raindrops (those greater than 3.5 mm, (0.14 inches)in diameter). These updrafts are filled with turbulent wind pockets that toss small raindrops around with surprising force. Within the turmoil of the randomly moving drops, there are more collisions among the drops than a bumper car ride, and many of those close encounters result in their conglomeration into new drops larger in size. Eventually all updrafts collapse, and when they do, the upheld raindrops descend unimpeded toward the surface, often forming a strong downdraft — such as a downburst or microburst — in the process, an event that appears as if the cloud has burst open like a soggy paper bag. So, not only are the larger drops falling with a terminal velocity of around 12 km/h (20 mph), but they have the added giddy-up of the downdraft speed, which can easily exceed 80 km/h (50...
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