Cumulus:  Detached domes or towers which are usually dense and well defined; develops vertically in the form of rising mounds of which the bulging upper part often resembles a cauliflower; composed of a great density of small water droplets, frequently supercooled; larger drops often develop within the cloud and fall from the bases as trails of evaporating rain (virga); ice crystals sometime form in the upper portion and grow larger by taking water from the water droplets; maximum frequency and development in the afternoon over land and during the night over water.



Cumulus congestus:  Cumulus clouds that show extensive vertical development.  They may form in rows, such as these, or as individual clouds that appear as a head of cauliflower.  Showery precipitation may fall from cumulus congestus.  This type usually develops very rapidly into the cumulonimbus.




Cumulus types:  The clouds with much smaller vertical extent are called cumulus humilis.  This cloud is an indication of fine, fair weather.  The very small ragged-looking clouds are called cumulus fractus.  These clouds are broken by turbulence.



Cumulonimbus:  Heavy and dense cloud, with a considerable vertical extent, in the form of a mountain or a massive tower; often with tops in the shape of an anvil or vast plume; base of cloud often very dark with low ragged clouds either merged with it or not; frequently accompanied by lightning and thunder, and sometimes hail; occasionally produces a tornado or a waterspout; the ultimate manifestation of the growth of a cumulus cloud, occasionally extending well into the stratosphere.



Mammatus:  Downward moving air causes these clouds to hang from the base of another cloud - most often a cumulonimbus or an altostratus.  This type of "boiling" cloud appears at the beginning of a squall or just before.



Stratus     Middle     High