Introduction
Waves are formed by the wind blowing across the surface of the ocean. The size of the wave is determined by three factors
- The intensity of the wind
- The length of time for which the wind blows
- The distance for which the wind blows
The longer and stronger the wind blows, the greater the wave action, until distinct lines of swell are formed. As the swell approaches the land, the waves become higher and the distance between successive waves, called the wavelength, becomes shorter.
Types of Waves
There are three main types of waves. Plunging, Spilling and Surging waves.
Plunging
Plunging waves break with a tremendous force and can throw a swimmer to the bottom. They usually occur at low tide, when the sand banks are shallow and there is less water for the waves to break onto. This wave is dangerous and is a common cause of spinal injuries.
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Spilling
Spilling waves occur when the crest (top) of the wave tumbles down the face(front) of the wave. As the tide gets lower and the sandbank on which the waves are breaking becomes more shallow, this type of wave will form tunnels or "tubes". Generally, spilling waves are the safest waves.
Surging
Surging waves may never actually break as they approach the waters edge, as a result of the water being very deep beneath them. They do not lose speed or gain height. Surging waves can knock swimmers off their feet and carry them back into deep water. For this reason they can be very dangerous especially around rocks.
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