Pulse storm
Encyclopedia
A pulse storm is a single cell thunderstorm
Thunderstorm
A thunderstorm, also known as an electrical storm, a lightning storm, thundershower or simply a storm is a form of weather characterized by the presence of lightning and its acoustic effect on the Earth's atmosphere known as thunder. The meteorologically assigned cloud type associated with the...

 that is usually not very strong; when it is of substantial intensity, it only produces severe weather
Severe weather
Severe weather phenomena are weather conditions that are hazardous to human life and property.- Examples Include :Severe weather can occur under a variety of situations, but three characteristics are generally needed: a temperature or moisture boundary, moisture, and , instability in the...

 for short periods of time. Such a storm weakens and then generates another short burst
-- hence "pulse." Pulse storms ordinarily form in environments with low wind shear and moderate instability, with the low wind shear
Wind shear
Wind shear, sometimes referred to as windshear or wind gradient, is a difference in wind speed and direction over a relatively short distance in the atmosphere...

 contributing a short average lifespan of less than an hour. Severe weather in a pulse storm will most often occur during a momentarily forceful updraft, taking the form of hail or particularly damaging winds brought about by downburst
Downburst
A downburst is created by an area of significantly rain-cooled air that, after reaching ground level, spreads out in all directions producing strong winds. Unlike winds in a tornado, winds in a downburst are directed outwards from the point where it hits land or water...

s. Rarely, a weak tornado
Tornado
A tornado is a violent, dangerous, rotating column of air that is in contact with both the surface of the earth and a cumulonimbus cloud or, in rare cases, the base of a cumulus cloud. They are often referred to as a twister or a cyclone, although the word cyclone is used in meteorology in a wider...

develops in association with a pulse storm.

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