Detached, dense clouds with a dome-shaped upper surface with sharp-edged, rounded protuberances and a nearly horizontal base; 600-6000 m or more; convective motion with rising, large bubbles of warm air with vertical speeds of 1-5 m s-1.
Source:
PAC, 1990, 62, 2167. 'Glossary of atmospheric chemistry terms (Recommendations 1990)' on page 2180 (https://doi.org/10.1351/pac199062112167)