“In physics, a breaking wave is a wave whose amplitude reaches a critical level at which some process can suddenly start to occur that causes large amounts of wave energy to be dissipated. At this point, simple physical models describing the dynamics of the wave will often become invalid, particularly those which assume linear behavior” (http://en.wikipedia.org/wiki/Wave_breaking).

“A complex phenomenon in which the surface of the wave folds or rolls over and intersects itself. In the process it may mix (entrain) air into the water and generate turbulence. The causes of wave breaking are various, for example, through the wave steepening as it approaches a beach, through an interaction with other waves in deep water, or through the input of energy from the wind causing the wave to steepen and become unstable” (http://amsglossary.allenpress.com/glossary/browse? s = w&p = 11).