"Mammatus Clouds, or 'breast-clouds', are fascinating formations in the sky, made mostly from the cumulus cloud base. Although they are not a sign that a tornado is about to form, they often accompany tornado-producing storms, or even may be direct byproduct of tornado activity - an aftermath of severe thunderstorms."The exact processes that lead to the formation of mamatus clouds is unknown.
"[Lenticular] clouds are often formed by so-called "mountain waves" of air created by strong winds forced over high mountains. Then they hang over the mountains like alien "motherships"... Mount Rainier in Washington produces some of the most spectacular lenticulars."
Although the clouds are virtually stationary, the air within is usually moving very rapidly, with water condensing as it enters the cloud zone and evaporating as the air leaves.