mountain-wave cloud
From Glossary of Meteorology
A cloud that forms in the rising branches of mountain waves and occupies the crests of the waves.
The most distinctive are the sharp-edged, lens-, or almond-shaped lenticular clouds, but a variety of stratocumulus, altocumulus, and cirrocumulus forms appear in both the main, vertically propagating waves and in the lee waves.
See mountain wave, foehn cloud.