Cloudburst

Hurricane Sandy

The Sandy Hurricane, the biggest ever in the recorded history, hit the shore of USA on Monday, the 29th October, 2012. Its extraordinary width (about 1517 km -the distance between Delhi to Kolkata) and velocity resulting from an unusually undulating Arctic Jet Stream combining with a southern tropical storm. The epic storm that lashed eastern United States an d eastern Canada, claimed more than 100 lives and sparking burglaries in flooded neighborhoods as nearly 4 million struggled without power and here. The damage according to one estimates 'projects up to $ 30 to 45 billion in lost economic revenue'. The maximum damage to life and property was in the states of New York and New Jersey. New York, one of the greatest cities and the commercial capital of USA was the worst affected. The storm waters flooding the city's subway and auto-tunnels damaging property and triggering a warning about a New Jersey nuclear plant facing rising water levels. The US nuclear power plants at New Jersey and New York were shut down on Tuesday in the aftermath of super storm Sandy.

The real cause of the origin of Sandy is not known but most of the scientists of climatic change are of the opinion that it was caused or made worse by human-induced global warming. In Sandy's trail, Americans should start seriously considering climate change. It has been established that Arctic-ice cap melting, darker waters are absorbing more heat, causing jet-streams to become slower and wavier-like the jet stream driving Sandy Hurricane. The financial misery caused by Hurricane Sandy should make America to realize to the economic perils of rampant climate change.

America is not only one of the biggest greenhouse gas emitter (China is another big problem), it also has the technical inventiveness to come up with solution. Unfortunately, the United States of America did not signed the Kyoto Protocol. The world is in danger, but America itself faces some of the more extreme weather events. But can Sandy make Americans say 'we are the world' and goad the American political class into waking up to its responsibilities? The Earth's future depends on it.

Cloudburst

A cloudburst is a sudden rainfall which can be quite unexpected, very abrupt, characterized with ash flood. In other words, cloudburst is an extreme amount of precipitation, sometimes with hail and thunder, which normally lasts no longer than a few minutes but is capable of creating havoc conditions of flood, landslides, avalanches, solidification, mud, earth, debris- avalanche, rock fall, subsidence, slumps, soil creep, and mass wasting.

Generally, cumulus-nimbus clouds which can extend up to a height of 15 km above the sea level, are involved in a cloudburst. In some cloudbursts, up to 13 centimeters (5 inches) of rain can fall in one hour, often in the form of extremely large droplets. In brief, the term cloudburst is used to describe sudden heavy, brief and usually unpredictable rainfall.

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 more quickly as they grow. The Langmuir Precipitation process is applicable only to those clouds which do not extend beyond the freezing point. The temperature in the uppermost part of the cloudburst seldom falls below 5'C. The occurrence of precipitation from such cumulus- nimbus clouds involves the coalescence of cloud droplets of different sizes. Since the rate of fall of these unequal rain-drops is different, they collide with each other within the cloud, and the larger drops grow at the expense of smaller ones. The size of the rain drops become slightly large which fall faster, and results into cloudburst. Sometimes, the rain in a cloudburst falls so fast and is so large that it is actually scary, frightening and painful.

According to the meteorologists the rainfall rate equal to greater than 10 cm (3.94 inches) per hour in a cloudburst. The associated convective (cumulus ' nimbus) clouds, have great vertical extension. During a cloudburst, more than 20 mm (2 cm) of rainfall may fall in a few minutes. At the occurrence of a cloudburst loss of property and human life is frequent which may take the shape of disaster and catastrophe. The Uttarakhand cloudburst on 16th June, 2013 is an example of large scale destruction of human life and economic structure. Because of the amount of rainfall involved, a cloudburst can be quite dangerous, especially if it persists for several hours. Flash flood is common with cloudburst, and in areas with arroyos, fishes, and other gullies, these geological features can quickly with water, sweeping away any people and animals which might be in the region. Flooding can also render streets unusable, and in extreme cases it can shut down entire city (like Kedarnath, Rambara, Gaurikund, Guptkashi, etc.) as people struggle to cope with the influx of water. The Uttarakhand cloudburst known as Himalayan Tsunami of 16th June, 2013 is an example of one of the worst cloudburst disasters in the recent history of India.

Often, these rainstorms appear in the summer season, and in the farming communities, they are sometimes welcomed, as a cloudburst can irrigate the withering crops very thoroughly. Most people try to avoid being caught out in the weather. Drowning have also been linked with cloudbursts, even without widespread flooding, because people can become disoriented when caught outside in severe weather.

In the Indian subcontinent, a cloudburst usually occurs when a moisture laden monsoon cloud drift northward, from the Bay of Bengal or Arabian Sea across the plains, then on to the Himalaya and bursts, bringing rainfall as high as 75 millimeters per hour.

Table 6.2   Cloudburst Damage in India in recent past  
         
Year   Place of cloudburst Deaths
       
August, 1998   Gowalpara (Assam) 400
July, 1970   Alaknanda Basin (Uttarakhand) 500
15th August, 1997 Chirgaon-Shimla District (H.P.) 115
August, 17, 1998   Milpa Village, Kumaun Division (Uttarakhand) 250
July 26, 2004   Mumbai cloudburst (Maharashtra) >5000
August 6, 2010   Leh-Ladakh (J & K) >1000
June 16, 2013   Kedarnath cloudburst (Uttarakhand) Several thousands

 

No comments yet.

Leave a Reply