Explainer: Understanding cloudbursts, their causes, and devastating impacts
A cloudburst is a sudden, intense, localized rainfall event that can cause severe damage, particularly in mountainous regions. The India Meteorological Department (IMD) defines a cloudburst as over 100 mm of rain in one hour over an area of about 20-30 sq. km, a threshold used to identify flash flood and landslide risks. The World Meteorological Organisation (WMO) defines it as 100 mm per hour or more, or 60 mm per hour for short bursts. Physically, cloudbursts occur when strong updrafts in thunderstorms hold large amounts of water, which is suddenly released when the updraft collapses. Orographic lifting, where moist air is forced upwards by mountains, also contributes to rapid condensation and heavy rain, leading to these short-lived but highly destructive events.
Key Points
- Cloudbursts are sudden, intense, and localized rainfall events capable of causing severe damage, especially in mountainous areas.
- The India Meteorological Department (IMD) defines a cloudburst as more than 100 mm of rain in one hour over 20-30 sq. km.
- The World Meteorological Organisation (WMO) defines cloudbursts as 100 mm per hour or more, or 60 mm per hour for short bursts.
- Physically, cloudbursts result from the sudden collapse of strong updrafts in thunderstorms that hold large amounts of water.
- Orographic lifting, where moist air is forced up mountains, is another key physical process contributing to rapid condensation and heavy rainfall in cloudbursts.
Exam Facts
- IMD definition: >100 mm rainfall in one hour over 20-30 sq. km.
- WMO definition: >100 mm per hour, or 60 mm per hour for short bursts.
- Cloudbursts are often linked to flash floods and landslides in mountainous areas.
- The Swedish term 'skyfall' is referenced by WMO.
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