Strong gusts of wind blowing in the same direction as the wind-wave propagation will cause the surface current to increase rapidly. The extra momentum supplied by the wind will take some time to diffuse downward from the surface, and the resulting vertical current shear and associated vorticity field will reduce the limiting height for non-breaking waves (Banner and Phillips 1974; Dalrymple 1974). Thus, existing wind waves will tend to break more vigorously, and their amplitude will be reduced for a while. Conversely, wind blowing in the direction against the wave propagation will tend to increase the limiting height, so that the waves will be able to reach a greater amplitude before they break. The effect of wind blowing with or against the wave propagation direction was studied for near-shore breaking waves by Douglass (1990) in laboratory experiments. His results confirm that a wind blowing with the waves, i.e. on-shore, tends to make the waves break sooner, in deeper water. If the wind blows off-shore, against the wave propagation, the wave breaking is delayed, and the waves tend to form plunging breakers closer to the shore. Or onshore
winds cause waves to break earlier, in deeper water, and to spill; offshore
winds cause waves to break later, closer to shore, and to plunge.
Wind's effect on breaker depth is significant. Wind's effect on breaker height is slight. Wind's effect on breaker height-to-depth ratio is significant. Most of the influence of wind on the breaker height-to-depth ratio is due to the wind's effect on shifting the location of breaking and thus changing the breaker depth. This influence of wind on height-to-depth ratio has important implications in surf zone dynamics models that use the ratio as a breaking criterion.
Wind's effect on breaker type will also affect the amount of sediment moving as suspended sediment. Higher suspended sediment loads have been found under plunging breakers than under spilling breakers (Fairchild 1972). Breaker type also has a significant effect on wave height decay after breaking. Wave forces on piles (Reddish and Basco 1987) and other structures in the surf zone are sensitive to the breaker type.
Wind's effect on breaker depth is significant. Wind's effect on breaker height is slight. Wind's effect on breaker height-to-depth ratio is significant. Most of the influence of wind on the breaker height-to-depth ratio is due to the wind's effect on shifting the location of breaking and thus changing the breaker depth. This influence of wind on height-to-depth ratio has important implications in surf zone dynamics models that use the ratio as a breaking criterion.
Wind's effect on breaker type will also affect the amount of sediment moving as suspended sediment. Higher suspended sediment loads have been found under plunging breakers than under spilling breakers (Fairchild 1972). Breaker type also has a significant effect on wave height decay after breaking. Wave forces on piles (Reddish and Basco 1987) and other structures in the surf zone are sensitive to the breaker type.