Any disturbance of the sea surface will create waves that propagate away from the source. Cyclical accelerations of water parcels are created by a combination of gravity and pressure gradient forces. These closed trajectories are localized, but the wave pattern moves through space and can be modeled using sinusoidal functions, as we considered in the previous section.
These waves on the ocean surface are often called surface gravity waves, because of the importance of gravity acting as a restoring force. Familiar examples include the larger waves found breaking on a beach (created in distant parts of the ocean by storms), smaller waves created by local wind, boat wakes and tsunamis.