Cumulonimbus incus

Cumulonimbus incus
A Classic Anvil Cloud Over Europe.jpg
A cumulonimbus incus cloud, showing the characteristic anvil-top shape the cloud type displays
AbbreviationCb inc.
GenusCumulonimbus (heap, cloud/severe rain)
SpeciesCapillatus (fibrous)
AppearanceLarge flat-top cloud
Precipitation cloud?Yes, often intense

A cumulonimbus incus (Latin incus, "anvil") also known as an anvil cloud is a cumulonimbus cloud which has reached the level of stratospheric stability and has formed the characteristic flat, anvil-top shape. It signifies the thunderstorm in its mature stage, succeeding the cumulonimbus calvus stage. Cumulonimbus incus is a sub-form of Cumulonimbus capillatus.


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's a highly unstable environment (which favors a more vigorous storm updraft).
  • Heavy rain; this cloud may drop several inches 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.
Other Languages
čeština: Incus
Deutsch: Incus (Wolke)
galego: Incus
日本語: かなとこ雲
norsk: Amboltsky
norsk nynorsk: Amboltsky
português: Cumulonimbus incus
slovenčina: Cumulonimbus incus
svenska: Incus