Cloudbursts in India, Meaning, Causes, Effects, Examples, UPSC Notes!

A cloudburst is an extreme weather event involving sudden, intense, and highly localised rainfall—often exceeding 100 mm per hour—within a short span of time. Common in Himalayan and other mountainous regions, cloudbursts are triggered when warm, moisture-laden air currents rise rapidly and collide with cooler air at higher altitudes, leading to the formation of cumulonimbus clouds. When these clouds can no longer hold the accumulated water, it is released in a torrential downpour, frequently accompanied by thunderstorms, causing flash floods and landslides.

Cloudburst is an important topic for the UPSC IAS exam as it forms a critical part of geography subject in Mains GS Paper 1 and Prelims GS Paper 1. 

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In this article, we shall discuss in detail about cloudburst, its formation, causes & effects for the UPSC exam. 

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What is Cloudburst?

Cloudbursts are intense bursts of extreme rainfall, often localized. A large amount of water dumps in a short period, potentially triggering flash floods and landslides. It is sometimes accompanied by thunderstorms and hailstorms. It is quite common in India’s mountainous states like Himachal Pradesh, Uttarakhand, Sikkim, etc. 

Some properties of cloudbursts have been discussed below: 

• Any rainfall amounting to more than 10 cm or 100 mm within a span of 60 minutes is characterized as a cloudburst. 
• The geographical area considered for such a short span of intense rainfall is 20 to 25 square kilometers. 
• Cloudbursts follow the Langmuir precipitation process as small rainfall droplets amalgamate to form large droplets. 
• One of the most devastating consequences of cloudbursts is flash floods. It is a situation of rapid flooding in low-lying areas after an intense spell of rain.

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Why do cloudbursts happen?

Cloudbursts happen mainly due to the rapid uplift of warm, moisture-filled air over mountains, a process known as orographic rainfall. When this moist air rises quickly along steep slopes, it cools and forms large, intense cumulonimbus clouds. Strong upward winds within these clouds trap raindrops, allowing them to grow very large. Eventually, the heavy water droplets fall suddenly, causing a brief but extremely heavy localized rainfall over a small area—often more than 100 mm in an hour.

This sudden heavy rain, typical in the Himalayan region during the southwest monsoon, often triggers flash floods and landslides. Additionally, cloudbursts can lead to Glacial Lake Outburst Floods (GLOFs), where heavy rains or melting glaciers cause glacial lakes to overflow or burst, worsening flood damage downstream.

Read the article on Urban Flooding in India!

How does cloudburst happen?

In India, cloudburst is quite common in the mountainous areas of North east, upper and middle Himalayas. It occurs in the months of June and July when southwest monsoon winds sail from the Arabian Sea and Bay of Bengal and bypass plains and move towards the hilly northern part of India. 

Cloudburst phenomena occur initially when the moisture-laden clouds do not cause any rainfall due to the upward movements of an extremely hot air current. Due to this hot air current, the raindrops become bigger in size, and instead of falling down, they continue to move up. Moreover, high relative humidity, along with low temperature and slow wind speeds, results in condensation of clouds at lightning speed. The warm air below restricts the falling of water from these clouds, and over time moisture level in these clouds becomes so big that it suddenly comes down as a severe spell of rain over a limited geographical area within minutes. One of the major causes of cloudbursts is the formation of cumulonimbus clouds.

Events of cloudbursts are very common during the southwest monsoon season. India’s Himalayan states and UT, like Himachal Pradesh, Uttarakhand, Jammu and Kashmir, Ladakh, Sikkim, and Arunachal Pradesh, regularly witness the heavy loss of life and property due to this natural disaster. 

Read the article on the Causes and Examples of Major Flash Floods in India!

Detecting and forecasting cloudbursts in India remains a significant challenge due to the sudden and localized nature of these extreme rainfall events. Cloudbursts are intense bursts of rain, usually occurring over a small area and short duration, often leading to flash floods and landslides, especially in the Himalayan and other mountainous regions.

Why is detection and forecasting of Cloudbursts difficult?

• • Rapid Formation: Cloudbursts develop very quickly, often within minutes, due to the fast upward movement of warm, moist air in mountainous terrain. This leaves a very narrow window for meteorologists to identify and issue warnings.
  • Localized Impact: Cloudbursts affect areas typically spanning only 20 to 25 square kilometers. Such a small spatial scale makes it hard for conventional weather monitoring tools, which usually cover larger areas, to detect and precisely forecast these events.

• Limitations of Satellite and Radar Technology

• • Weather Satellites: While satellites provide broad coverage and track cloud movement, their resolution is often insufficient to capture the fine-scale dynamics of cloudbursts. They can indicate conditions conducive to heavy rainfall but not always the exact timing or location of a cloudburst.
  • Weather Radars: Radars help by monitoring precipitation intensity and movement but have limitations in mountainous regions due to complex terrain that can block radar signals. Additionally, the spatial resolution of many radars is larger than the typical cloudburst scale.
  • Some advanced Doppler radars with enhanced resolution and sensitivity are being developed and deployed in parts of India, which improve detection capabilities but are still limited in number and geographic coverage.

• Inadequate Ground Monitoring: Automatic weather stations on the ground can measure rainfall and other weather parameters accurately but are sparse in remote and rugged mountainous areas where cloudbursts frequently occur. This lack of dense ground-based sensors reduces early detection capabilities.
   

Read the article on the Flash Flood Disasters!

Examples of Cloudbursts in India

Some examples of recent cloudbursts in India are as follows:

Read the article on Floods in India!

Here are some of the most important consequences of a cloudburst:

• Flash Floods: Sudden surges of water quickly inundate low-lying areas, damaging homes, roads, and bridges.
• Landslides and Mudslides: The heavy rain loosens soil, rocks, and debris on slopes, causing destructive landslides that block roads and endanger lives.
• Loss of Life and Properties: Disasters lead to deaths, injuries, displacement, and destruction of infrastructure.
• Environmental Damage: Flooding uproots trees, kills wildlife, and disrupts ecosystems.
• Land Subsidence: Heavy water saturation causes land to sink or settle suddenly.
• Population Displacement: Many affected people must migrate temporarily or permanently, challenging rehabilitation efforts.

What effect does climate change have on cloudbursts?

Rising temperatures cause more moisture to be held in the atmosphere, fueling more intense rainfall and increasing the likelihood of cloudbursts. Climate change also destabilizes weather patterns and increases the frequency of thunderstorms. Melting glaciers and altered land use, like deforestation and urbanization, further influence regional microclimates, contributing to cloudburst risks. As a result, such extreme events are becoming more frequent and severe, especially in the Himalayan region.

Read the article on DANA or Cold Drop!

How can we mitigate the impact of cloudbursts?

To reduce the impacts of cloudbursts, efforts focus on:

• Early Warning Systems: Improve meteorological monitoring and forecasting technology to provide timely alerts.
• Disaster Preparedness: Educate and train communities on emergency response and evacuation protocols.
• Resilient Infrastructure: Build flood-resistant roads, bridges, and drainage systems. Use slope stabilization and green infrastructure like trees to reduce landslide risk.
• Land Use Regulation: Avoid construction in high-risk floodplains and landslide-prone areas.
• Watershed Management: Implement soil erosion control and promote water infiltration to reduce flood impact.
• Research and Collaboration: Invest in R&D and work with international and regional bodies to share technology and best practices.
• Climate Action: Address broader climate change to reduce the frequency and severity of extreme rainfall events.

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