Scene notes:

The scientific adage of ‘what goes up, must come down’ rings true in this scene where, at right, lower-level clouds rise in convection. Over this ridgeline, there are pockets of air that fall through the cloud as cold patches, creating these distinctive looking clouds. While the dire, dark gray, bizarre looking ‘mammatus’ are this size only 30-40000 ft and attached to monstrous storms, these are clearly harmless clouds.
Time-lapse length (30 fps):
7 seconds and 15 frames.