{{Short description|Thunderstorm that produces severe weather for short periods}} A '''pulse storm''' is a [[Storm cell|single cell]] [[thunderstorm]] of substantial intensity which only produces [[severe weather]] for short periods of time. Such a storm weakens and then generates another short burst – hence "pulse". The term was coined by researchers at the [[National Severe Storms Laboratory]] in 1979 to describe a single [[storm cell]] briefly becoming severe within a cluster of [[multi-cellular thunderstorm]]s, but has since been used to describe a variety of isolated and brief thunderstorms with both severe and non-severe characteristics.<ref>{{cite journal |last1=Miller |first1=Paul W. |last2=Mote |first2=Thomas L. |title=Standardizing the Definition of a “Pulse” Thunderstorm |journal=Bulletin of the American Meteorological Society |date=May 2017 |volume=98 |issue=5 |pages=905–913 |doi=10.1175/BAMS-D-16-0064.1|doi-access=free}}</ref>
__TOC__ ==Description== Single cell thunderstorms ordinarily form in environments with low [[wind shear]] and moderate instability, with the low wind shear contributing to a short average lifespan of less than an hour.<ref>{{cite web|url=http://www.theweatherprediction.com/habyhints2/400/ |title=What is a pulse storm?|website=www.theweatherprediction.com|author=Jeff Haby|accessdate=February 20, 2020}}</ref> When the instability, calculated by [[convective available potential energy]] (CAPE), is strong, the [[updraft]] will bring a larger amount of humid air very high above ground and generate a [[cumulonimbus cloud]] with high water and ice content.<ref name=IL/> When the rain content, and even [[hail]], falls from it, they can generate damaging winds brought about by [[downburst]]s. Rarely, a weak [[tornado]] develops in association with a pulse storm as the environment is only weakly sheared, or not at all.<ref>{{cite web|url=https://forecast.weather.gov/glossary.php?letter=p|work=Glossary|publisher=US National Weather service|title=Pulse storm|accessdate=February 20, 2020}}</ref>
==Life cycle== [[File:Orage ordinaire multilingue.svg|thumb|Life cycle of a pulse storm.]] One can distinguish three stages in the evolution of a pulse storm:<ref name=IL>{{cite web|url=http://ww2010.atmos.uiuc.edu/(Gh)/guides/mtr/svr/type/sngl/ev.rxml |title=Evolution of a Single Cell Storm|website=ww2010.atmos.uiuc.edu |publisher=University of Illinois|author=Departement of Atmospheric Sciences|accessdate=2020-02-19}}</ref>
*Formation: the upward current of the cell intensifies and allows the condensation of water vapor from the rising air parcel. This forms a [[cumulus congestus]] or a [[towering cumulus]], then a [[cumulonimbus]] when ice crystals form at its apex which spreads horizontally in contact with the tropopause. *Maturity: downdrafts are emerging. This stage is accompanied by characteristic phenomena such as [[lightning]] and [[thunder]], [[Shower (precipitation)|showers]], and [[Outflow boundary|gust front]]. *Dissipation: the cold pool descending from the cloud extends to the Earth's surface and helps to block the feed by pushing the updraft downstream. The [[Outflow (meteorology)|outflow]] can then serve as a trigger for other single cell or even multi-cell thunderstorms to develop because the Outflow boundary is a lifting mechanism for updrafts because it can force more warm humid air into the atmosphere.
==See also== *[[Project NIMROD]]
==References==
{{Reflist}}
[[Category:Severe weather and convection]]
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