Ac flo

Altocumulus floccus
species of Altocumulus

Altocumulus consisting of small tufts if cumuliform appearance; the lower parts of these tufts are more or less ragged and are often accompanied by fibrous trails (virga of ice crystals). The presence of these clouds is an indication of instability at their level. Altocumulus floccus sometimes forms as a result of the dissipation of the base of Altocumulus castellanus.