Castellanus Cloud Species: Rising Towers, Turrets

Definition: Vertical, conjoined cloud castles that generally indicate instability

Description & Characteristics. The ‘castellanus’ cloud species can be found amongst four cloud types: cirrus, cirrocumulus, altocumulus, and stratocumulus. Translated from latin, meaning castle, the four types of castellanus clouds are respectively abbreviated as ‘Ci cas’, ‘Cc cas’, ‘Ac cas’, and ‘Sc cas’. When looking for castellanus clouds, keep your eye out for rising cumuliform towers usually with a connected base.

The castellanus species of cloud is uncommon, but can be expected to be seen on days when the atmosphere is unstable. Altocumulus castellanus clouds are sometimes abbreviated as ACCAS and are a particular favorite kind of cloud amongst storm chasers because they usually point to unstable air, which can mean for thunderstorm development sometime during the day. Castellanus clouds in the morning indicate stormy weather in the afternoon.

The castellanus species of cloud is uncommon, but can be expected to be seen on days when the atmosphere is unstable. Altocumulus castellanus clouds are sometimes abbreviated as ACCAS and are a particular favorite kind of cloud amongst storm chasers because they usually point to unstable air, which can mean for thunderstorm development sometime during the day. Castellanus clouds in the morning indicate stormy weather in the afternoon.

Castellanus cloud formations can be found paired with cloud varieties duplicatus (multilayered) and radiatus (parallel bands and strips), as well as with virga (evaporating rain strips) on occasion.

Castellanus Cloud Types


The castellanus cloud species is associated with the following four cloud types: cirrus, cirrocumulus, altocumulus, and stratocumulus.

High, wispy streaks

High-altitude cloudlets

Mid-altitude cloud heaps

Low, puffy layer