Cumulus castellanus cloud

Cumulus castellanus
Cumulus castellanus low on the horizon
Appearance	Flat on the bottom, though has multiple "towers" on top
Precipitation	Usually, but not always

Cumulus castellanus (from Latin castellanus, castle) is an unofficial name of a species of cumulus cloud that is distinctive because it displays multiple towers arising from its top, indicating significant vertical air movement. It is a misnomer for cumulus congestus and correspondingly can be an indicator of forthcoming showers and thunderstorms. The World Meteorological Organization and the American Meteorological Society do not recognize cumulus castellanus as a distinct species, but instead classify all towering cumulus clouds as Cumulus congestus.