Editing Surfing (section)

=== Wave formation ===
[[Ocean wave]]s 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.<ref name=Talley2011 /> Wind causes ripples and [[Eddy (fluid dynamics)|eddies]] to form waves that gradually gain speed and distance (fetch). Waves increase in energy and speed and then become longer and stronger.<ref name=Scarfe2009 /> The fully-developed sea has the strongest wave action that experiences storms lasting 10-hours and creates {{Convert|15|m|ft|abbr=on|sigfig=3}} wave heights in the open ocean.<ref name=Talley2011 />

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 reaching the bottom of the water basin.<ref name=Talley2011 /> Deep water waves are waves in water depths greater than half their wavelengths.<ref>{{cite web |title=Wave Energy and Wave Changes with Depth |url=https://manoa.hawaii.edu/exploringourfluidearth/physical/waves/wave-energy-and-wave-changes-depth#:~:text=Deep%2Dwater%20waves%20are%20waves,%3E%201%2F2%20L). |access-date=21 September 2024}}</ref> Wind forces waves to break in the deep sea.{{clarify|date=February 2021}}

Deep-water waves travel to shore and become shallow-water waves when the water depth is less than half of their wavelength, and the wave motion becomes constrained by the bottom, causing the orbit paths to be flattened to [[ellipse]]s. The bottom exerts a frictional [[Drag (physics)|drag]] on the bottom of the wave, which decreases the celerity (or the speed of the waveform), and causes refraction. Slowing the wave forces it to shorten which increases the height and steepness, and the top (crest) falls because the velocity of the top of the wave becomes greater than the velocity of the bottom of the wave where the drag occurs.<ref name=Talley2011>{{cite book|last=Talley |first=Lynne D. |title=Descriptive Physical Oceanography: An Introduction |date=2011 |publisher=Academic Press |isbn=978-0-08-093911-7 |pages=223–244 |chapter=Chapter 8. Gravity Waves, Tides, and Coastal Oceanography }}</ref>

The surf zone is the place of convergence of multiple waves types creating complex wave patterns. A wave suitable for surfing results from maximum speeds of {{Convert|5|m/s|ft/s}}. This speed is relative because local onshore winds can cause waves to break.<ref name=Scarfe2009 /> In the surf zone, shallow water waves are carried by global winds to the beach and interact with local winds to make surfing waves.<ref name=Scarfe2009 /><ref name=Madsen1997 />

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.<ref name=Scarfe2009 /><ref name=Madsen1997>{{cite journal |last1=Madsen |first1=P.A. |author2=O.R. Sørensen, and H.A. Schäffer |date=1997 |title=Surf zone dynamics simulated by a Boussinesq type model. Part I. Model description of cross-shore motion of regular waves |journal=Coastal Engineering |volume=32 |issue=4 |pages=255–287 |doi=10.1016/S0378-3839(97)00028-8|bibcode=1997CoasE..32..255M |issn = 0378-3839}}</ref> Light offshore winds create smoother waves, while strong direct offshore winds cause plunging or large barrel waves.<ref name=Scarfe2009 /> 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.<ref name=Scarfe2009 /> Off-shore winds produce non-surfable conditions by flattening a weak swell. Weak swell is made from surface gravity forces and has long wavelengths.<ref name=Scarfe2009 /><ref name=Edge2001>{{cite journal |last=Edge |first=Ronald |date=2001 |title=Surf Physics |journal=The Physics Teacher |volume=39 |issue=5 |pages=272–277 |doi=10.1119/1.1375464|bibcode=2001PhTea..39..272E }}</ref>