Altocumulus (Ac) - the name derives from the latin words altus = high and cumulus = mass or heap. Altocumulus is a member of the ten fundamental cloud types (or cloud genera). It is a middle-level cloud, thus they usually form between 2 to 7 kilometers (6,500 to 22,000 ft).
Altocumulus cloud usually occur as a layer or patch of more or less separate cloudlets in the form of heaps, rolls, billows or pancakes. They are white and/or gray in colour with generally shadowed parts or undersites and often show a waved aspect. They may be well shaped by high winds into lentels or rippled wave patters and might appear as a pancake tower or like an UFO, often sharply outlined, but they may also become partly fibrous and diffuse. They may or may not be merged.
Altocumulus clouds chiefly consist of super-cooled water droplets of minus 10C, but ice crystals are often present. Usually they do not produce rain, but might indicate a weather change within a day or so. Altocumulus are extremely varied. They might occur in the
What do altocumulus tell about the weather?