Cumulonimbus incus

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.[1] It signifies a thunderstorm in its mature stage, succeeding the cumulonimbus calvus stage.[2] Cumulonimbus incus is a sub-form of Cumulonimbus capillatus.

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.
SymbolClouds CL 9.svg
GenusCumulonimbus (heap, cloud/severe rain)
SpeciesCapillatus (Having hair)
AltitudeGround to 23,000 m
(75,000 ft)
ClassificationFamily C (Low-level)
AppearanceLarge flat-top cloud
PrecipitationVery common Rain, Snow, Snow pellets or Hail, heavy at times


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 favours a more vigorous storm updraft).
  • Heavy rain: this cloud may drop several inches (millimetres) 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.


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.

In popular cultureEdit

  • It is a key plot point in the anime Tenki no Ko (Weathering With You).


  1. ^ "Incus".
  2. ^ "Cumulonimbus Incus - EPOD - a service of USRA".

External linksEdit