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Xilover Surf Shop
4500 Irving St, San Francisco, CA 94122
CALL US: (415) 564-6300

Wave formation
Ocean waves are defined as a collection of dislocated water parcels that undergo a cycle of being forced past their normal position and being restored back to their normal position.[29] Wind caused ripples and eddies form waves that gradually gain speed and distance (fetch). Waves increase in energy and speed, and then become longer and stronger.[30] The fully developed sea has the strongest wave action that experiences storms lasting 10-hours and creates 15 meter wave heights in the open ocean.[29]

The waves created in the open ocean are classified as deep-water waves. Deep-water waves have no bottom interaction and the orbits of these water molecules are circular; their wavelength is short relative to water depth and the velocity decays before the reaching the bottom of the water basin.[29] Deep waves have depths greater than ½ their wavelengths. Wind forces waves to break in the deep sea.

Deep-water waves travel to shore and become shallow water waves. Shallow water waves have depths less than ½ of their wavelength. Shallow wave's wavelengths are long relative to water depth and have elliptical orbitals. The wave velocity effects the entire water basin. The water interacts with the bottom as it approaches shore and has a drag interaction. The drag interaction pulls on the bottom of the wave, causes refraction, increases the height, decreases the celerity (or the speed of the wave form), and the top (crest) falls over. This phenomenon happens because the velocity of the top of the wave is greater than the velocity of the bottom of the wave.[29]

The surf zone is place of convergence of multiple waves types creating complex wave patterns. A wave suitable for surfing results from maximum speeds of 5 meters per second. This speed is relative because local onshore winds can cause waves to break.[30] In the surf zone, shallow water waves are carried by global winds to the beach and interact with local winds to make surfing waves.[30][31]

Different onshore and off-shore wind patterns in the surf zone create different types of waves. Onshore winds cause random wave breaking patterns and are more suitable for experienced surfers.[30][31] Light offshore winds create smoother waves, while strong direct offshore winds cause plunging or large barrel waves.[30] Barrel waves are large because the water depth is small when the wave breaks. Thus, the breaker intensity (or force) increases, and the wave speed and height increase.[30] Off-shore winds produce non-surfable conditions by flattening a weak swell. Weak swell is made from surface gravity forces and has long wavelengths.[30][32]