Cumulus clouds are a type of cloud with noticeable vertical development and clearly defined edges. Cumulus means heap or pile in Latin. They are often described as puffy or cotton-like in appearance. Cumulus clouds may appear alone, in lines, or in clusters. 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. Cumulus clouds are part of the larger family of cumuliform clouds, which include cumulus, cumulus congestus, and cumulonimbus clouds, among others. The most intense cumulus and cumulonimbus clouds may be associated with severe weather phenomena such as hail, waterspouts and tornadoes.