Cumulus clouds are probably the most recognized clouds out of all of the cloud types. Cumulus clouds form below 6,000 feet, but in some extreme cases they can be in altitudes as high as 39,000 feet. They are white puffy clouds that look like cotton balls. They have a lifetime of five to forty minutes, and are known for their flat bases and lumpy outlines. Cumulus clouds appear so fluffy because bubbles of air, called thermals, linger in the cloud making it have this kind of look. Fair weather is usually associated with cumulus clouds, but they can cause short and heavy rainfall. These clouds are also partly responsible for creating cold front systems. Cumulus clouds are formed by frontal lifting or convection, which is simply the rising of warm air, which then cools and condenses to form a cumulus cloud.
Cumulonimbus clouds are larger and are more like tall towers than regular cumulus clouds. Cumulonimbus clouds exist from near ground to 50,000 feet up in the air. The clouds can exist as individual towers of clouds, or there can be a squall line. A squall line is a line of tower cumulonimbus clouds. The tops of this type of cloud often spread out in a shape of an anvil or plume. Fast-moving convective updrafts fuel these clouds to reach such great heights, and these, like other clouds, can be made of ice crystals as their main component in cold temperatures. Sometimes the cloud can contain both liquid water droplets and ice crystals when the freezing point is in the middle of the cloud. Fair weather cumulus clouds can form into cumulonimbus clouds in the right conditions. Cumulonimbus clouds are associated with powerful thunderstorms. Snow, rain, hail, lightning, thunder, and sometimes tornadoes can accompany cumulonimbus clouds.
Altocumulus clouds lie at a range from 6,000 to 20,000 feet. Altocumulus clouds are usually made of water droplets but can be composed of ice crystals at higher elevations. Parallel bands of cloud or rounded cotton balls, like in this picture, usually signify altocumulus clouds. One part of the cloud is darker than the rest of the cloud, which makes it easy for one to tell the difference between these clouds and different types of cirrus clouds. The slow uplift of warm air from a cold front pushing its way through near the ground causes altocumulus clouds to form. Thunderstorms can follow a warm and humid summer morning in the presence of this particular type of cloud.
Stratocumulus clouds form in altitudes below 6,000 feet. They do not significantly change the weather, and they appear in layers, rows, or patches. A low layer of stratocumulus clouds appear near sunset and are the spreading remains of larger cumulus clouds. Precipitation does not usually fall from stratocumulus clouds even though their color may be from dark to light gray. They are different from altocumulus clouds because they are slightly larger. One neat way to determine the difference between altocumulus and stratocumulus clouds is that standing on Earth, altocumulus clouds are about the size of a human thumb nail while stratocumulus clouds are the size of a fist.