{{Short description|Type of cumulus cloud}} {{Use British English|date=November 2021}} {{Use dmy dates|date=November 2021}} {{Infobox cloud type | name = Cumulonimbus incus | image location = A Classic Anvil Cloud Over Europe.jpg | image name = A cumulonimbus incus cloud, showing the characteristic anvil-top shape the cloud type displays | abbreviation = Cb inc. | symbol = Clouds_CL_9.svg | genus = Cumulonimbus (''heap, cloud/severe rain'') | species = Capillatus (''Having hair'') | variety = None | altitude_m = Ground to 23,000 | altitude_ft = 75,000 | level = low | appearance = Large flat-top cloud | precipitation = Very common rain, snow, snow pellets or hail, heavy at times | thickness = | ice content = }}
A '''cumulonimbus incus''' ({{etymology|la|{{Wikt-lang|la|incus}}|anvil}}), also called an '''anvil cloud''', is a cumulonimbus cloud that has reached the level of stratospheric stability and has formed the characteristic flat, anvil-shaped top.<ref>{{cite web |url=https://cloudatlas.wmo.int/en/clouds-supplementary-features-incus.html |title=Incus}}</ref> It signifies a thunderstorm in its mature stage, succeeding the cumulonimbus calvus stage.<ref>{{cite web |url=https://epod.usra.edu/blog/2009/08/cumulonimbus-incus.html |title=Cumulonimbus Incus |publisher=EPOD (service of USRA)}}</ref> Cumulonimbus incus is a subtype of cumulonimbus capillatus. These clouds are commonly associated with severe weather, including heavy rain, downbursts, and occasionally a tornado.
==Hazards== A '''cumulonimbus incus''' is a mature thunderstorm cloud generating many dangerous elements.
*Lightning: this storm cloud is capable of producing bursts of cloud-to-ground lightning. *Hail: hailstones may fall from this cloud if it is a highly unstable environment (which favours a more vigorous storm updraft). *Heavy rain: this cloud may drop several inches (centimetres) of rain in a short amount of time. This can cause flash flooding. *Strong wind: gale-force winds from a downburst may occur under this cloud. *Tornadoes: in severe cases (most commonly with supercells), it can produce tornadoes. They are not directly produced by cumulonimbus incus but rather produced by supercells which come from cumulonimbus incus.
==Classification== thumb|Cumulonimbus incus over Africa, seen from the International Space Station Cumulonimbus clouds can be powerful. If the correct atmospheric conditions are met, they can grow into a supercell storm. This cloud may be a single-cell thunderstorm or one cell in a multicellular thunderstorm. They are capable of producing severe storm conditions for a short amount of time.
==References== {{Reflist|30em}}
==External links== {{commons category}}
{{Cloud types}}
Category:Cumulus Category:Cirrus