Kelvin-Helmholtz instability, which transforms fair weather clouds into the form of crashing ocean waves, is a rare and wondrous phenomenon. One of the best examples I’ve ever seen is in a video ...

HERMANN v. HELMHOLTZ. Helmholtz's Treatise on Physiological Optics. Translated from the third German edition. Edited by By Prof. James P. C. Southall. Vol. 2: The Sensations of Vision. Pp.