They tend to appear on these five cloud types: cirrus, altocumulus, cumulus, stratus, and stratocumulus. But it's equally rare to find fluctus clouds in each one, according to the International ...

or a series of lenticular clouds, is capable of forming. These are often mistaken for UFOs because of the saucer-like shape. They can separate into altocumulus standing lenticular, stratocumulus ...