Gravity wave
The term gravity waves is used in oceanology , meteorology and planetology for waves whose propagation is dominated by the acceleration of gravity . They have nothing to do with gravitational waves , which are an entirely different phenomenon.
There are basically two types of gravity waves:
- External gravity waves propagate along the interface between two fluids . One mechanism of formation of external gravity waves is the Kelvin-Helmholtz instability .
- Internal gravity waves occur within a medium with continuous, stable stratification. If the amount of the density gradient does not have a pronounced maximum, the energy of the wave can be distributed over a depth range that is large compared to the wavelength .
Examples
Lee waves behind mountain ridges or island mountains are stationary internal waves. See also Mountain Wave Project .
The same effect occurs in lakes and seas, for example at river mouths or when flowing over obstacles.
Water waves are mostly gravity waves, but see capillary waves .