Lenticular clouds form on the downwind side of mountains. Wind blows most types of clouds across the sky, but lenticular clouds seem to stay in one place. Air moves up and over a mountain, and at the point where the air goes past the mountaintop the lenticular cloud forms, and then the air evaporates on the side farther away from the mountains. Lenticular clouds are lens-shaped and look like flying saucers.