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Heat Burst

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Article Information
Category: Weather Weather
Content source: SKYbrary About SKYbrary
Content control: SKYbrary About SKYbrary
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Tag(s) Weather Phenomena

Description

A heat burst occurs when hot dry air from a dying thunderstorm accelerates quickly towards the surface causing strong winds and a sudden significant temperature increase.

Temperature curve recorded at Donna Nook, Lincolnshire, UK on evening of 25 July 2019, associated with collapsing thunderstorm, showing 10C spike in surface temperature - source: UK Met Office

Mechanism

Thunderstormlifecycle.jpg

When a thunderstorm begins to dissipate, most of the air within it is moving downwards (downdraft). If warm dry air is present in the middle levels of the storm, any rainfall will evaporate immediately (see Virga). While this cools the air down somewhat, the warm air continues to descend towards the surface which warms it up quickly because of the increasing pressure (Adiabatic processes). the rapidly descending warm dry air pushes air out from below causing strong winds outwards from beneath the thunderstorm.

Characteristics

Since Heat bursts are associated with a decaying thunderstorm, this rare phenomenon occurs most commonly in the late evening or at night. They are also more common in the summer months.

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