•Gravity waves are waves generated in a fluid medium or
at the interface between two
media (e.g., the atmosphere and the ocean) which has the restoring force of gravity or buoyancy.
•When a fluid element is displaced on an interface or
internally to a region with a different
density, gravity tries to restore the parcel toward equilibrium resulting in an oscillation about the equilibrium state or wave
orbit.
•Gravity waves on an air-sea interface are called surface
gravity waves or surface waves
while internal gravity waves are called internal waves.