What causes waves to break on shore?
As waves move towards shore, they begin to “feel” the ocean floor. In a process known as shoaling, this causes the wave orbitals to flatten as the bottom shoals. When waves feel the bottom they slow down and bunch together (decrease their wavelength); but the time between wave crests (period) does not change. The height of the wave will initially decrease when it feels bottom, but then will steadily increase until the wave becomes unstable and breaks near the beach. The water literally falls over. Waves expend the energy they gained from the wind by transferring that energy to the beach when they break.
