What is the difference between cumulus clouds and alto-cumulus clouds?

Answer 1

Altocumulus (Alto, "high", cumulus, "heaped") is a cloud belonging to a class characterized by globular masses or rolls in layers or patches, the individual elements being larger and darker than those of cirrocumulus and smaller than those of stratocumulus. Like other cumulus clouds, altocumulus signifies convection. It is usually white or gray, and often occurs in sheets or patches with wavy, rounded masses or rolls. Altocumulus often are seen preceding a cold front, and their presence on a warm, humid, summer morning frequently signals the development of thunderstorms later in the day. Alto means high and these clouds may cause rain if they are higher up. One form of altocumulus, altocumulus lenticularis (Lenticular cloud) is frequently reported as "Unidentified flying objects".The altocumulus approach can sometimes be frightening, for the cloud has a dark and scary appearance. Altocumulus clouds are found at an altitude of between 2,000 and 6,000 metres and are made up entirely of water droplets. Sometimes they form parallel bands, as here, and sometimes rounded masses. They often form in front of a cold front as unstable air is lifted. this is alto cumulus clouds in a clear mackerel pattern Altocumulus cloud formation A stratocumulus cloud belongs to a class characterized by large dark, rounded masses, usually in groups, lines, or waves, the individual elements being larger than those in altocumuli, and the whole being at a lower altitude, usually below 2,400 m (8,000 ft). Weak convective currents create shallow cloud layers because of drier, stable air above preventing continued vertical development. Vast areas of subtropical and polar oceans are covered with massive sheets of stratocumuli. These may organize in to distinctive patterns which are currently under active study. In subtropics, they cover the edges of the horse latitude climatological highs, and reduce the amount of solar energy absorbed in the ocean. When these drift over land the summer heat or winter cold is reduced. 'Dull weather' is a common expression incorporated with overcast stratocumulus days. If the air over land is moist and hot enough they may develop to various cumulus clouds, or, more commonly, the sheets of thick stratocumuli may have a nimbostratus look on them. The distinction here is the amount of rain produced. On drier areas they quickly dissipate over land, resembling cumulus humilis. Generally, stratocumuli bring only light rain or snow. However, these clouds are often seen at either the front or tail end of worse weather, so may indicate storms to come, in the form of thunderheads or gusty winds. These are same in appearance to altocumuli and are often mistaken for such. A simple test to distinguish these is to compare the size of individual masses or rolls: when pointing your hand in the direction of the cloud, if the cloud is about the size of your thumb, it is altocumulus; if it is the size of your entire hand, it is stratocumulus. Stratocumulus lenticularis clouds in Jackson, WY

Stratocumulus clouds viewed from above the Rocky Mountains