What is the phenomenon of ‘Cloudbursts’? Explain.

According to the India Meteorological Department (IMD), 100 mm of rain in one hour is called a cloudburst. Usually, cloudbursts occur over a small geographical region of 20 to 30 square kilometers. Ministry of Earth Science reported(2021) that due to climate change from 1969 there is increased incidence of 5 cloudburst per decade especially on Westcoast and Himalayan region.

## Mechanism of Cloudbursts

• Clouds condense– When moisture-carrying air climbs a mountainous terrain, it forms vertical columns of clouds calledcumulonimbus clouds. These clouds produce rain, thunder, and lightning


• orographic lift– The unstable clouds generate a strong deluge over a constrained region after becoming heavy enough and locking in the valleys and ridges between the hills


• The air’supward momentumprovides the cloudburst with the energy it needs to occur. Most cloudbursts take place between 1,000 and 2,500 metres above sea level, and they are followed by significant flooding and landslides.


• Atmospheric disturbances: Low-pressure systems lead to the rapid development of convective clouds and heavy rain.Eg-cloud bursts andheavy rainfallduring cyclonic events inOdisha


• Convergence of air masses:The collision of warm, moist air with cooler, denser air lead to rapid upward movement of warm air causing Cloudbrust


• High Humidity Levels: Eg-Mumbai (2005)experienced a cloudburst due to extremely high humidity levels coupled with monsoon winds. Over 944 mm of rain fell in a single day, leading to severe flooding and disruption.

## Consequences of cloudbursts

• Flash Floodstriggered by severe thunderstorms, dam failures, or rapid snowmelt. Eg- Himachal Pradesh and Uttarakhand Flash Floods in August 2022


• Landslides: involving the downward movement of rock, earth, or debris. Eg- Landslide in Pithoragarh district of Uttarakhand


• Spread of communicable diseases– Waterborne diseases (cholera, typhoid fever etc.,), vector-borne diseases (dengue, malaria etc.,) spreads rapidly during floods.


• Disruption of communication –It damages transportation links such as bridges, rail, and power plants thus causing communication disruption.


• Coastal cities-flash floods make the conventional stormwater and flood management policies in these cities dysfunctional. Eg- Chennai floods

## NDMA Guidelines for Effective Mitigation of the Impact of Cloud Bursts

• Early warning systems


• Disaster preparedness:emergency plans involving evacuation routes and safe locations.


• Infrastructure improvement: drainage systems, embankments etc.


• Land-use planning:ImplementingMishra Committee Report

Deploying Multiple Doppler weather radars to monitor moving cloud droplets and to provide forecast for the next 3 hours along with  Proper community sensitisation regarding the causes, effects and safety precautions of cloudbursts is the need of the hour.

Click to Access Full Notes