In meteorology, a heat burst is a rare atmospheric phenomenon characterised by gusty winds and a rapid increase in temperature and decrease in dew point (moisture). Heat bursts typically occur during night-time and are associated with decaying thunderstorms.[1]
Although this phenomenon is not fully understood, it is theorized that the event is caused when rain evaporates (virga) into a parcel of cold dry air high in the atmosphere making the air denser than its surroundings.[2] The parcel descends rapidly, warming due to compression, overshoots its equilibrium level and reaches the surface, similar to a downburst.[3]
Recorded temperatures during heat bursts have reached well above 90 °F (32 °C), sometimes rising by 20 °F (11 °C) or more within only a few minutes. More extreme events have also been documented, where temperatures have been reported to exceed 130 °F (54 °C), although such extreme events have never been officially verified. Heat bursts are also characterised by extremely dry air and are sometimes associated with very strong, even damaging, winds.
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