Explained: Why cloudbursts could become more frequent

In News:

  • At least seven people were killed and 17 injured after a cloudburst hit remote Hunzar village, of the hilly Kishtwar district of Jammu and Kashmir.

About Cloudburst:

  • Cloudbursts are short-duration, intense rainfall events over a small area.
  • A cloudburst is different from rain only in the amount of water that pours down on the earth.
  • The India Meteorological Department (IMD)categorises rainfall over 100 mm/houras cloudburst. Usually small areas – anywhere between 20-80 square kilometres are affected.
  • Rainfall over 50 mm/hour is categorised as a mini-cloudburst.

Cloudburst process- How does it happen?

  • The process of cloudburst begins as the warm air current from the ground or below the cloud rush upwards.
  • While it moves up, it carries the falling raindrops up with it.

  • As the rainfall fails to fall down, it results in excessive condensation in the clouds as new drops form and old drops are pushed back into it due to the conversion process.
  • The air current slows down resulting with a violent downpour in a region.
  • The results of cloudbursts can be disastrous. Cloudbursts are also responsible for landslides and flash flood creation.

Role of topography:

  • The severity of cloudbursts differs based on terrain.
  • A cloudburst usually occurs in high-altitude areas due to the formation of a low-pressure area on the top of a mountain.
  • The low-pressure zone attracts clouds to the top of the mountain with great force.
  • When they hit the peak, the moisture content is released in the form of rain.
  • Large volumes of water gain momentum as it flows in gushes, resulting in landslides.
  • In the plains, cloudbursts cause waterlogging and flash floods.

India’s scenario:

  • In the Indian subcontinent, a cloudburst usually occurs when a monsoon cloud drifts northwards, from Bay of Bengal or Arabian Sea across the plains, then onto the Himalayas and bursts.
  • The most disastrous cloudburst was report in India in the state of Uttarakhand in 2013 where more than 5,400 people were killed and 4,200 villages were affected.

Are cloudbursts becoming more frequent?

  • As per a report titled ‘Assessment of Climate Change over India 2020’ released by the Ministry of Earth Sciences, the Indian subcontinent,during the period of 1969-2015, experienced 130 mini-cloudburst events and one cloudburst event per year.
  • Earlier, cloudbursts were common during monsoon or post-monsoon period, which is September-October. Now, they are occurring sooner every year.
    • For example, the Uttarakhand floods (2013) caused by a cloudburst, occurred in the month of June.

Cause:

  • The main reason behind increased frequency of cloudbursts is climate change.
  • It has caused increased global temperatures and changes in wind pattern.
  • As temperatures increase the atmosphere can hold more and more moisture and this moisture comes down as a very intense rainfall for a short duration, resulting in flash floods in the mountainous areas and urban floods in the cities.

 Environment & Ecology

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