DTE Explains: The science of cloudbursts

Telangana Chief Minister said cloudbursts may be a 'foreign consipiracy' during his visit to flood-hid Bhadrachalam

By Preetha Banerjee
Published: Monday 18 July 2022

India, especially its Himalayan states Himachal Pradesh and Uttarakhand, are devastated by cloudbursts several times moslty during the monsoon season. Flash floods caused by a cloudburst in Uttarakhand in 2013, killing thousands of people, is one of the worst natural disasters the country recorded since the 2004 tsunami. 

Climate change has been making these extreme weather events more frequent and intense, according to meteorologists

In 2021, Himachal Pradesh recorded around 30 cloudburst events and Uttarakhand 50, according to South Asia Network on Dams, Rivers and People, a network of organisations that work on related issues. SANDRP collated data from news articles on these disasters. 

This year is no better: Flash floods that followed a cloudburst near Amarnath caves in Jammu & Kashmir July 8, 2022 left 17 dead and around 40 injured as of July 16, state authorities announced. Over 60 people are still missing, according to official records. One of the first incidents of cloudburst this year was in Budgam district in Jammu & Kashmir on May 9, when at least one person died.  

A couple of days earlier, around six tourists were washed away in a similar incident in Himachal Pradesh’s Kullu district. 

The swollen Godavari river due to incessant rainfall also resulted in floods in Bhadrachalam, a temple town in Telangana, killing at least 15 people over the past week, according to official data. 

Telangana Chief Minister K Chandrashekar Rao, who visited the flood-hit area July 17, said the repeated cloudburst incidents are a result of a foreign conspiracy, media reports quoted. 

He, however, acknowledged that climate change may also be a contributing factor, as suggested by experts.  

This brings us to the question: Why do cloudbursts happen? 

A cloudburst is sudden spell of localised, heavy rainfall. 

The India Meteorological Department defines cloudburst as the condition where the amount of rainfall over a particular area exceeds 100 millimetres in an hour. 

They often result in flash floods and have become increasingly common from May-September when the southwest monsoon season prevails in much of the country. 

The phenomenon that is responsible for this large amount of precipitation in such a short duration is ‘orographic lift’. It is the process by which clouds that are already to rain are pushed up by warm air currents. 

As they reach higher elevations, the water droplets within the clouds become bigger and new ones are formed. Lightning within these clouds help in delaying rainfall. 

These dense clouds eventually burst, unable to hold the large volume of moisture. This results in torrential downpours in the geographical region right below and leads to overflowing of water bodies in a very short duration of time.

The phenomenon is more common in mountainous areas because they offer the terrain for moisture-laden air to rise swiftly along the mountain slopes. 

A doppler-radar system is ideal for predicting the calamity and demands were made to equip monitoring stations in cloudburst-prone areas with this system following the 2013 in Uttarakhand. 

Stations with the technology are still few and far between even in the Himalayan states, making forecasting difficult, noted experts.

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