The Development and Evolution of Cumulus Humilis Clouds In order for clouds to form, a few factors are crucial to begin their formation. Clouds, since they are primarily water-based with small amounts of other materials (hygroscopic condensation nuclei), need a ready source of water so evaporation can move the water from a lake or the like, into the atmosphere. Once in the atmosphere, the sun heats the air, causing it to rise, and eventually condense …showed first 75 words of 329 total…

…showed last 75 words of 329 total…of the clouds evaporate, cooling the surrounding air, making it increase in density and fall in altitude. The sinking of the air surrounding the cloud prevents further mixing of the warm and cold air, otherwise known as convection. Because of the air being so still, there is no way for warm air to rise then condense creating another cloud. This is the reason for the large amount of blue sky associated with cumulus humilis clouds.