The
Kelvin–Helmholtz instability (after
Lord Kelvin and
Hermann von Helmholtz) can occur when there is
velocity shear in a single
continuous fluid, or where there is a velocity difference across the interface between two fluids. An example is wind blowing over water: The instability manifests in waves on the water surface. More generally, clouds, the ocean, Saturn's bands, Jupiter's Red Spot, and the sun's corona show this instability.