Why do we study winds?
Winds have great effect on wave generation, and thus have a great effect on offshore and onshore facilities. In fact, wind interaction on the surface of the ocean far from the coast can create some of the best waves on earth. Winds can not only affect the wave shape in shallow-water area, but also change the breaking points. Local shore winds usually destroy the quality of the breaking waves. Onshore winds are typically known for creating choppy and bumpy waves because they push in the direction of the wave, making them unstable. In a way, offshore winds act as a sort of a counterbalance. Swell comes from miles away, and the ground wind works as a "pause-hold" effect on the wave face, pushing against it and allowing longer, unbreakable waves.
Here is a video on wind wave that causes huge damage on onshore facilities along south coast of UK.
A swell, in the context of an ocean, sea or lake, is a series of mechanical waves that propagate along the interface between water and air and so they are often referred to as surface gravity waves. These series of surface gravity waves are not generated by the immediate local wind, instead by distant weather systems, where wind blows for a duration of time over a fetch of water. After the wind has abated or shifted or the waves have migrated away from the wind field, wind waves continue to propagate as swell.
In fluid dynamics, 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 transformed into turbulent kinetic energy. At this point, simple physical models that describe wave dynamics often become invalid, particularly those that assume linear behaviour.
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Here is a side view of experimental wave breaking shot by Water Research Laboratory, UNSW # 060708.
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As a swell approaches the coastline and comes into contact with the sea floor the waves will start to slow down. Some of the waves' energy is lost through contact with the sea floor. The shallower the water becomes the slower they move. As they slow down they have to squash together. (i.e. they shorten their wave period.) This process is called shoaling and results in increasing wave height. The steeper the sea floor gradient the more pronounced the wave height will increase. The increase in wave height begins to occur at depths of around one half of the wavelength.