Altocumulus

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. These clouds are of medium altitude, about 8000-20,000 feet (2400-6100 meters). A middle cloud, usually white or gray, often occurs in layers or patches with wavy, rounded masses or rolls.

Altocumulus (Ac) A principal middle level cloud type (cloud genus), white or gray, or both white and gray, which occurs as a layer or patch with a wave aspect, the elements of which appear as laminae, rounded masses, rolls, etc. These elements usually are sharply outlined, but they may become partly fibrous or diffuse; they may or may not be merged; they generally have shadowed parts; most of the regularly arranged Altocumulus elements usually have an apparent width of between one and five degrees.

A cloud of 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. These clouds are of medium altitude, about 8000-20,000 ft (2400-6100 m).