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Cloudburst "EMPOWER IAS"

In news:

  • Recently, cloudbursts have been reported from several places in J&K, Ladakh, Uttarakhand and Himachal Pradesh. A

 

What is cloud burst? 

  • The cloudburst is a localised weather phenomena representing highly concentrated rainfall over a small area lasting for few hours. This leads to flash floods/ landslides, house collapse, dislocation of traffic and human casualties on large scale. 
  • 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. 

 

What causes Cloudburst?

  • A study published last year studied the meteorological factors behind the cloudburst over the Kedarnath region.
  • They analyzed atmospheric pressure, temperature, rainfall, cloud water content, cloud fraction, cloud particle radius, cloud mixing ratio, total cloud cover, wind speed, wind direction, and relative humidity during the cloudburst, before as well as after the cloudburst.
  • The results showed that during the cloudburst, the relative humidity and cloud cover was at the maximum level with low temperature and slow winds.
  • It is expected that because of this situation a high amount of clouds may get condensed at a very rapid rate and result in a cloudburst.

 

Prone areas

  • They occur most often in desert and mountainous regions, and in interior regions of continental landmasses. 
  • The topographical conditions like steep hills favour the formation of these clouds in the mountainous regions. And also the devastations, as water flowing down the steep slopes bring debris, boulders and uprooted trees with great velocity damaging any structure that comes in their way.
  • The Chhotanagpur plateau spread across north Odisha, West Bengal and Jharkhand is the world’s most vulnerable spot for formation of severest thunderstorms.
  • Cloudburst can occur not only in the monsoon seasons but also during March to May which is known for severe convective weather activities.

 

Effect of Cloudbursts

  1. Flash floods
  2. Accompanying effect of Cloudbursts on terrain
    • Landslides
    • Mudflows
    • Land caving
  • Flash floods – houses and establishments getting swept away and cave-ins lead to the deaths.
  • Blocking path of rivers that may lead to temporary damming and creation of a reservoir and its consequent collapse
  • The rainfall itself does not result in the death of people, though sometimes, the raindrops are big enough to hurt people in a sustained downpour. It is the consequences of such heavy rain, especially in the hilly terrain, that causes death and destruction.

 

Frequency of cloudbursts

  • There is a paucity of past data on cloudbursts; in addition, since only some of them get counted – only those that result in death and destruction – there is a problem of accuracy as well.
  • But what is very clear is that events of extreme precipitation have been on the rise in the last few decades; keeping temperature fluctuations in mind as a trend, that cloudburst events might be on the increase as well.

 

Impact of climate change

  • Several studies have shown that climate change will increase the frequency and intensity of cloudbursts in many cities across the globe.
  • As temperatures increase the atmosphere can hold more and more moisture and this moisture comes down as a short very intense rainfall for a short duration.
  • This results in flash floods in the mountainous areas and urban floods in the cities.
  • Also, there is evidence suggesting that globally short duration rainfall extremes are going to become more intense and frequent.