Sea Waves
The main factor in the formation of sea waves on the open ocean is wind. When winds blow across water, they apply a pressure due to friction, which pushes the water up, creating a wave. Within a wave, each water particle travels in a circular motion before returning to its original position. The wave will grow higher as long as the wind is strong enough to add energy. Once a wave is generated, it will travel in the same direction until it meets land or is dampened by an opposing force such as winds blowing against it. Once a wave moves away from the wind that generated it, it is called swell. Eventually this swell will flatten and broaden, but little or no energy is lost as it journeys across an ocean or sea. It is the surge of energy that moves rather than the individual water particles, rather in the manner of a longitudinal wave on a rope that is shaken, when it is the pulse not the rope fibres that move forward.
Waves can be classified into two main types, constructive and destructive. Constructive waves cause sediment to build up on beaches. They are most common when the fetch is large and the beach angle is gradual. The waves are flat and low, and their swash (the forward motion of the wave up the beach) is much stronger then their backwash (the backward motion of water returning from a previous wave). Sediment builds up slowly on the shore because only six to eight waves break on the shore every minute. Destructive waves help to remove sediment from beaches. They are more common when the fetch is short and the beach angle steep. The waves are steep and high, with a stronger backwash than swash. This allows the ten to fourteen waves breaking every minute to drag sediment offshore.