Accessory cloud types can form at various altitude ranges depending on the main clouds with which they are associated. The World Meteorological Organization classifies most accessory clouds as "supplementary features". The height range classification of a supplementary feature is the same as the parent cloud. As an example, the anvil cloud (supplementary feature incus) forms at high altitude but is not classified by the WMO as a high cloud because of its association with the genus cumulonimbus. It is "very rare" for any accessory cloud to generate its own precipitation. However, the parent cloud may generate precipitation. Precipitation from the parent cloud
Altocumulus castellanus cloud Altocumulus castellanus cloud In meteorology, Altocumulus Castellanus (ACCAS) is a cloud type named for its tower-like projections that billow upwards from the base of the cloud. The base of the cloud can form as low as 2,000 metres (6,500 feet), or as high as 6,000 metres (20,000 feet). They are very similar to cumulus congestus clouds, but at a higher level and with the cloud heaps joined at the base. Castellanus clouds are evidence of mid-atmospheric instability and a high mid-altitude lapse rate. They may be a harbinger of heavy showers and thunderstorms and, if surface-based convection can connect to