Lenticular cloud, Mt. Fuji, Japan

Altocumulus lenticularis is one of the more obviously 'bizarre' cloud types -- they don't occur too frequently, so when you see one, you take notice. They often form above or near mountains, as moist air flows rapidly over a rise in elevation. Mt. Fuji makes a pretty sweet base for this one. 

Where is the cloud? Is it all over the sky? The cloud is over top of the snow. Would the cloud from without the snow on Mt. Fuji? No, it would not. The blanket cloud forms because water vapor became cold and condensed. It became sold and condensed because of the temperature difference in the air where the snow exists and where it does not.

Hold on to that thought.