Cumulus cloud
Cumulus clouds are often precursors of other types of clouds, such as cumulonimbus, when influenced by weather factors such as instability, moisture, and temperature gradient. Normally, cumulus clouds produce little or no precipitation, but they can grow into the precipitation-bearing congestus or cumulonimbus clouds. Cumulus clouds can be formed from water vapor, supercooled water droplets, or ice crystals, depending upon the ambient temperature. They come in many distinct subforms, and generally cool the earth by reflecting the incoming solar radiation. Cumulus clouds are part of the larger category of free-convective cumuliform clouds, which include cumulonimbus clouds. The latter genus-type is sometimes categorized separately as cumulonimbiform due to its more complex structure that often includes a cirriform or anvil top. There are also cumuliform clouds of limited convection that comprise stratocumulus (low-étage), altocumulus (middle-étage) and cirrocumulus (high-étage). These last three genus-types are sometimes classified separately as stratocumuliform.
Cumulus cloud
The species "Cumulus fractus" is ragged in appearance and can form in clear air as a precursor to cumulus humilis and larger cumulus species-types; or it can form in precipitation as the supplementary feature "pannus" (also called scud) which can also include stratus fractus of bad weather. "Cumulus humilis" clouds look like puffy, flattened shapes. "Cumulus mediocris" clouds look similar, except that they have some vertical development. "Cumulus congestus" clouds have a cauliflower-like structure and tower high into the atmosphere, hence their alternate name "towering cumulus". The variety "Cumulus radiatus" forms in radial bands called cloud streets and can comprise any of the four species of cumulus.
Cumulus supplementary features are most commonly seen with the species congestus. "Cumulus virga" clouds are cumulus clouds producing virga (precipitation that evaporates while aloft), and "cumulus praecipitatio" produce precipitation that reaches the Earth's surface. "Cumulus pannus" comprise shredded clouds that normally appear beneath the parent cumulus cloud during precipitation. "Cumulus arcus" clouds have a gust front, and "cumulus tuba" clouds have funnel clouds or tornadoes. "Cumulus pileus" clouds refer to cumulus clouds that have grown so rapidly as to force the formation of pileus over the top of the cloud. "Cumulus velum" clouds have an ice crystal veil over the growing top of the cloud.