{{Short description|Weather phenomenon viewed from distance}} [[File:Rain shaft 1.jpg|alt=Dark storm clouds under which a grey sheet of rain is falling on a city.|thumb|right|upright=1.4|A rain shaft at the base of a thunderstorm]] {{Weather}}
A '''precipitation shaft''' or, depending on the precipitation type, a '''rain shaft'''<ref name="stull">{{cite book | title=Practical Meteorology | author=Roland Stull | publisher=University of British Columbia | url=https://www.eoas.ubc.ca/books/Practical_Meteorology/prmet102/Ch15-Thazards-v102.pdf | access-date=29 May 2025 | date=2017 | ISBN=978-0-88865-283-6}}</ref> or '''hail shaft''', is a weather phenomenon, often visible from the ground at large distances from the storm system, as a vertical shaft of heavy rain, hail, or snow, generally localized over a relatively small area. Depending on the type of precipitation and lighting, these shafts can vary greatly in color, appearing as very dark, nearly white, or even faintly glowing.
This is different from a virga, which is a shaft of precipitation that evaporates before reaching the ground.
==Formation==
A precipitation shaft is mostly found underneath convective clouds, such as cumulonimbus cloud or cumulus congestus cloud during a downpour storm, as these have well defined vertical drafts (updrafts and downdrafts) needed for heavy precipitation. However, an advancing nimbostratus cloud could have a diffuse precipitation leading edge, so its shaft may be unclear.{{citation needed|date=April 2016}}
Developing rain shafts often have a fuzzy, bulbous appearance as they descend. If a source of dry air is present at higher altitude and the air into which the rain is falling is sufficiently warm, then strong, possibly damaging microbursts are possible as sinking air forms.<ref>{{cite web|title=Rain Shaft has a fuzzy, bulbous appearance|url=http://ww2010.atmos.uiuc.edu/(Gh)/guides/mtr/svr/comp/out/micro/dvp.rxml|website=Weather World 2010|access-date=22 April 2016}}</ref> Wet microbursts, normally producing more than {{Convert|25|mm|in|abbr=on}} of rain at ground level, can strengthen downdraft, and cause more intense and widespread damage than dry microbursts.<ref>{{Cite journal |last=Hadavi |first=Mohammad |last2=Romanic |first2=Djordje |date=2024-08-01 |title=Atmospheric conditions conducive to thunderstorms with downbursts in Canada and a downburst precursor parameter |url=https://www.sciencedirect.com/science/article/pii/S0169809524002102 |journal=Atmospheric Research |volume=305 |article-number=107428 |doi=10.1016/j.atmosres.2024.107428 |issn=0169-8095|doi-access=free }}</ref>
==See also==
==References== {{Commonscat|Praecipitatio}} {{reflist}}
Category:Precipitation
{{meteorology-stub}}