| Cumulonimbus incus | |
|---|---|
 A cumulonimbus incus cloud, showing the characteristic anvil-top shape the cloud type displays | |
| Abbreviation | Cb inc. |
| Symbol |  |
| Genus | Cumulonimbus (heap, cloud/severe rain) |
| Species | Capillatus (Having hair) |
| Variety | None |
| Altitude | Ground to 23,000 m (75,000 ft) |
| Classification | Family C (Low-level) |
| Appearance | Large flat-top cloud |
| Precipitation | Very common rain, snow, snow pellets or hail, heavy at times |
A cumulonimbus incus (from Latin 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.[1] It signifies a thunderstorm in its mature stage, succeeding the cumulonimbus calvus stage.[2] Cumulonimbus incus is a subtype of cumulonimbus capillatus. These clouds are commonly associated with severe weather, including heavy rain, downbursts, and occasionally a tornado.