| Cirrocumulus castellanus | |
| Image Location: | Cirrocumulus castellanus undulatus and Cirrocumulus floccus.jpg |
| Image Name: | Cirrocumulus castellanus undulatus (on the center) |
| Abbreviation: | Cc cas |
| Symbol: | Clouds CH 9.svg |
| Genus: | Cirro- (curl) -cumulus (heaped) |
| Species: | Castellanus (castle) |
| Altitude M: | Above 6,000 |
| Altitude Ft: | Above 20,000 |
| Level: | high |
| Appearance: | small, rounded turrets |
| Precipitation: | Virga only |
Cirrocumulus castellanus or Cirrocumulus castellatus[1] is a type of cirrocumulus cloud. Castellanus is from the Latin meaning "of a castle".[2] These clouds appear as round turrets that are rising from either a lowered line or sheet of clouds.[3] Cirrocumulus castellanus is an indicator of atmospheric instability at the level of the cloud.[4] The clouds form when condensation occurs in the base cloud, causing latent heating to occur. This causes air to rise from the base cloud, and if the air ascends into conditionally unstable air, cirrocumulus castellanus will form.[5]