Cloudburst

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Content

• What is cloudburst?
• Mechanism: How does cloudburst occur?
• Other key aspects

What is cloudburst?

• A cloudburst refers to an extreme amount of rain that happens in a short period, sometimes accompanied by hail and thunder. IMD defines it as unexpected precipitation exceeding 10 cm per hour over a geographical region of approximately 20-30 sq km.
  • For e.g. the 2013 floods in Kedarnath were caused by Cloud Burst. In 2021, Amarnath region was impacted by cloudburst.

Impact: This sudden discharge of rain leads to floods including flash floods, landslides etc. which may result into human casualties, and property loss.

Mechanism: How does cloudburst occur?

• When cumulonimbus clouds (which stretch to even 13-14 kms in height) are trapped over a region or there is no air movement for them to disperse, they discharge over a specific area.
  • Here, saturated clouds ready to condense into rain can’t produce rain, due to the upward movement of the very warm current of air.
  • Instead of falling downwards, raindrops are carried upwards by the air current. New drops are formed and existing raindrops increase in size. After a point, the raindrop are too heavy for the cloud to hold on to, and they drop down together in a quick flash

Other key aspects

• It is very difficult to forecast the event due to its very small scale in space and time.
  • To monitor or nowcast (forecasting few hours of lead time) the cloudburst, we need to have dense radar network over the cloudburst-prone areas or one need to have a very high resolution weather forecasting models to resolve the scale of cloudburst. Doppler radar can be very useful in predicting them.
• Mountain regions are more prone to cloudburst due to orography (terrain and elevation), though they may occur in plains as well.

Way forward:

• Hazard zonation mapping: Identifying the areas vulnerable to flash floods.
• Improving forecasting (nowcasting) Infrastructure: Increasing the coverage of doppler radars.
• Currently Himalayan region has 7 doppler radars (2 each in J&K and Uttarakhand, 1 each in Assam, Meghalaya and Tripura.
• Building flood resistant infrastructure: To reduce damages due to flash floods
• Regulating settlements in the river banks
• Strengthening institutions to provide quick response at the time of cloudburst in the form of emergency evacuation, medicine etc.

Conclusion: Bay taking steps to predict, prepare, and respond to these events, we can reduce the loss of life and the property damage that they cause.

Practice Questions:

• Explain the mechanism and occurrence of cloudburst in the context of the Indian subcontinent. Discuss two recent examples. [Mains 2022, 10 marks, 150 words]
• Cloudbursts are often associated with flash floods. Explain the relationship between cloudbursts and flash floods and discuss the challenges in managing flash flood events. [10 marks, 150 words]