https://doi.org/10.1351/goldbook.C01441
Heavy masses of dense cloud whose cumuliform summits rise in the forms of towers, the upper parts having a fibrous texture and often spreading out into the shape of an anvil; these clouds generally produce showers of rain and sometimes of snow, hail or soft hail, and often develop into thunderstorms; up to ; summits may be as cold as ; strong convective motions with vertical velocities of to greater than .