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 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 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 mph). The resulting rainfall is a torrent of water, large raindrops falling at high speed, over a small area.
The force and quantity of such downpours can be damaging to vegetation, small animals, and property. When the speed of water accumulation on the ground exceeds the surface’s ability to absorb it, localized flooding will occur in low-lying terrain. In hilly or mountainous terrain, the runoff of water can congregate in stream beds or canyons and cause deadly and damaging flash flooding. Here are some world record cloudbursts: 1 minute: 1. 5 inches / 38. 1 mm at Barot, Guadeloupe, 26 November 1970. 5 minutes: 2. 43 inches / 61. 2 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, Rumania, 7 July 1947. 40 minutes: 9. 25 inches / 234. 95 mm at Guinea, Virginia, USA, 24 August 1906. Bright Cloudbursts During a cloudburst, we are usually thinking more about keeping dry or navigating our car safely through traffic. But have you ever watched the approach of a thunderstorm darken the sky and then been surprised at how bright the day became during the heaviest downpour?
We logically expect that, given the pre-rain darkness of a thunderstorm, that when heavy rainfall begins, the darkness will deepen. But very often, a sudden downpour comes with an unexpected brightening of the surroundings. Here’s why. Each raindrop can act as a reflector of any light falling on it (reflection and refraction of light through distant raindrops form bright, beautiful rainbows). During a heavy downpour, a large number of raindrops encircle us, and we are, in effect, caught in the rain of a large number of little mirrors.
As any interior decorator knows, you can brighten a room with a few lights by putting mirrors on the surrounding walls or ceilings. Thus, each light ray passing through the downpour undergoes multiple reflections so that the light reaching our eyes comes from all directions rather than just directly from the source. The most important factors in producing the rainfall-brightening around us are the raindrop quantity and the size distribution. In a cloudburst, the number of large drops is much greater than in a light rainfall.
Since the surface area of a drop increases as the square of its radius, a drop twice as large has four times the potential reflecting surface area. Thus, as these liquid mirrors get bigger, we become more effectively surrounded by reflecting surfaces, and this makes the scene appear brighter. A cloudburst is a sudden rainfall which can be quite unexpected, very abrupt, and rather drenching. In some cloudbursts, up to 5 inches (almost 13 centimeters) of rain can fall in an hour, often in the form of extremely large droplets.
Cloudbursts are especially common in the tropics, although they can occur anywhere, and they are often accompanied with thunder. They are also highly unpredictable, by nature, which can be very frustrating for weather agencies. The term “cloudburst” is the result of the fanciful idea that clouds are filled with water. Historically, some people believed that clouds were essentially like balloons, with solid membranes filled with liquid. In a cloudburst, these balloons would literally burst, pouring torrents of rain out. Although this theory has since been disproved, the term has stuck.
Typically, extremely high clouds are involved in a cloudburst, most classically cumulonimbus clouds. The hard rain characteristic of a cloudburst is caused by a phenomenon known as Langmuir precipitation, in which drops of rain fuse together to create large drops as they fall, falling every more quickly as they grow. Sometimes, the rain in a cloudburst falls so fast and is so large that it is actually a bit painful. Because of the amount of rain involved, a cloudburst can be quite dangerous, especially if it persists for several hours.
Flooding is common with cloudbursts, and in areas with arroyos, washes, and other gullies, these geological features can quickly fill with water, sweeping away any people and animals which might be inside. Flooding can also render streets unusable, and in extreme cases it can shut down an entire city, as people struggle to cope with the influx of water. Often, these severe rainstorms appear in the summer, and in farming communities, they are sometimes welcomed, as acloudburst can irrigate crops very thoroughly. Most people try to avoid being caught out in the weather, however, as they would otherwise be drenched to the skin.
Drownings have also been linked with cloudbursts, even without widespread flooding, because people can become disoriented when caught outside in severe weather. 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 flood conditions. Contents | ————————————————- Etymology 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 100mm (3. 94 inches) per hour. During a cloudburst, more than 2cm 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.
Record cloudbursts | Duration| Rainfall| Location| Date| 1 minute| 1. 5 inches (38. 10 mm)| Barot, Himachal Pradesh, India| 26 November, 1970| 5 minutes| 2. 43 inches (61. 72 mm)| Port Bells, Panama| 29 November, 1911| 15 minutes| 7. 8 inches (198. 12 mm)| Plumb Point, Jamaica| 12 May, 1916| 20 minutes| 8. 1 inches (205. 74 mm)| Curtea-de-Arges, Romania| 7 July, 1947| 40 minutes| 9. 25 inches (234. 95 mm)| Guinea, Virginia, USA| 24 August, 1906| ————————————————- Cloudbursts in the Indian 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. An example was the sudden cloud burst over the Indian city of Mumbai and other regions of western India, on 26 July 2005, during the 2005 Maharashtra floods. 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. 40 killed in Himachal cloudburst, flash floods By Kanwar Yogendra SHIMLA JULY 16. About 40 persons were killed in flash floods caused by a cloudburst at Shilagarh in Gursa area of Kullu sub-division, 265 km from here, early today, according to Government sources. (The State Government in a press release late tonight said 20 to 25 persons were missing. Sixteen bodies have been recovered.
The release said that out of 23 persons admitted to the Zonal Hospital, Kullu, one succumbed to his injuries. Unofficial sources have put the toll between 150 and 200) The Chief Minister, Virbhadra Singh, making a statement in the Assembly earlier in the day, said there were about 250 persons at the site at the time of the cloudburst, but so far only 22 persons have been brought for treatment to the Kullu Hospital. Officials said there were 300 to 400 workers, mainly of Nepalese and Bihari origin, camping at Gursa in two different camps.
Since the flash floods came when most workers were sleeping, the chances of survival were not very high. A majority of these labourers were working for a construction company building the 2100-MW Parvati Hydel Project in Kullu, being executed by the National Hydro Electric Power Corporation (NHPC). The exact location of the cloudburst was at Rauli, where a small bridge was under construction across the Gursa nullah, a tributary of the Beas. Two bridges and machinery worth lakhs were washed away. According to a local sub-contractor for the construction company, many of his 40 workers were missing.
They even had their families with them. Some of the petty contractors along with their groups of workers, each comprising 25 to 30 persons, have also been washed away. The Chief Minister said the Deputy Commissioner and Superintendent of Police of Kullu and officers from the PWD and Fire departments had reached the site for organising relief and rescue operations. The ITBP Battalion at Kullu, which had been given the task of “first responder” for natural and man-made disasters in the Himalayan areas by the Ministry of Home Affairs, had also been called upon to assist in disaster mitigation. Rs. 10-crore loss PTI reports:
Meanwhile, the NHPC has estimated a loss of about Rs. 10 crores due to damage to the machinery and bridges at the power project. “Work has been stopped temporarily at the site… We are hopeful of resuming the work within two to three days,” the NHPC Chairman and Managing Director, Yogendra Prasad, told PTI from New Delhi. No NHPC employee died in the incident. PM condoles deaths UNI reports from New Delhi: The Prime Minister, Atal Behari Vajpayee, today condoled the deaths of the people killed in the cloudburst. In his message, Mr. Vajpayee, who is on a visit to Kolkata, expressed his sympathies to the members of the bereaved families.