Info Nuggets

Decoding the difference: Cloudburst and flash floods explained

Chandigarh, Updated At : 07:49 PM Sep 02, 2025 IST

Definition: An extreme, sudden and very heavy rainfall (≥100 mm/hour in a localised area, often < 20–30 km²).

Cause:

• Occurs when warm air currents rapidly carry moisture-laden air upward.

• At higher altitudes, condensation happens quickly, leading to a massive downpour in a short time.

• Common in mountainous regions like the Himalayas.

Impact:

• Can trigger flash floods, landslides and damage to infrastructure.

• Not every cloudburst causes a flood, but many do if terrain is steep.

Definition: A sudden, violent flood that develops within minutes to hours of heavy rain, dam break or glacial lake outburst.

Cause:

• Intense rainfall (sometimes from a cloudburst).

• Rapid snowmelt or breach of natural/artificial barriers.

Impact:

• Water level rises very quickly.

• Sweeps away roads, houses, people and livestock.

• Can occur without a cloudburst (e.g., after a dam break).

Key difference

• Cloudburst = the cause (intense local rainfall event).

• Flash flood = the effect (sudden flooding that may or may not result from a cloudburst).

Example for clarity:

• Kedarnath 2013: A cloudburst + glacial lake outburst led to devastating flash floods.

Here’s a crisp UPSC-style comparison table for quick revision:

Cloudburst vs flash flood

Aspect	Cloudburst	Flash flood
Definition	Sudden, very heavy rainfall in a small area (≥100 mm/hour).	Sudden and violent flooding that develops within minutes to hours.
Nature	Meteorological event (extreme rainfall).	Hydrological event (sudden water flow).
Cause	Rapid condensation of moisture-laden air, often in mountainous regions.	Intense rainfall (often from cloudburst), dam/glacial lake breach or rapid snowmelt.
Scale	Very localised (10-30 km²).	Can affect larger downstream areas.
Timeframe	Rainfall occurs within minutes to a few hours.	Flood develops very quickly after trigger (minutes-hours).
Impact	Can trigger flash floods, landslides, soil erosion.	Sweeps away infrastructure, lives, crops, livestock.
Relation	A cause (extreme rainfall event).	An effect (sudden flooding event).
Example in India	Leh (2010), Uttarakhand (2013).	Kedarnath floods (2013), Himachal Pradesh flash floods (2023).

Mnemonic for exam:

• Cloudburst = Sky event (rainfall)

• Flash Flood = Ground event (flooding)