Sea waves created by the wind are an example..?
Rayleigh-Taylor instability
Kelvin-Helmholtz instability
This instability 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.