Cumulus Clouds (Clouds with Vertical Growth Group)
Picture by Carlye Calvin
Cumulus humilis clouds are common in the summer and are not associated with storms. They are usually widely spaced in the sky, have a flat base and rounded tops, and sometimes they look like sheep grazing in a pasture.
Cumulus congestus clouds, also called towering cumulus, are in the last stage of development before becoming cumulonimbus clouds. The tops of cumulus congestus clouds look like cauliflower, and sometimes light rain can fall from them. Once they become cumulonimbus clouds,thunderstorms with rain, hail, thunder and lightning can occur.
Picture by Gary Anthes/UCAR
UCAR digital image library