10.6: Sea and Swell
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Sea and Swell
• Sea: Area where wind waves are generated, mixed period and wavelengths. Seas are typically a chaotic jumble of waves of many different sizes (wave heights, wavelengths, and periods) (Figure 10.16).
• Fully Developed Sea: Max size waves can grow given a certain fetch, wind speed and duration.
Ocean swell refers to series of ocean surface waves that were not generated by the local wind. Swell refers to an increase in wave height due to a distant storm. Ocean swell waves often have a long wavelength. Swell can develop on lakes and bays, but their size varies with the size of the water body and wave intensity. As waves move out and away from the storm center, they sort themselves out into groups of similar speeds and wavelengths. This produces the smooth undulating ocean surface called a swell. Swells may travel thousands of kilometers from the storm center until they strike shore. Swells are generated by storms over the open ocean, but many ocean swells originate in the oceans around Antarctica where there is high winds with nearly infinite duration and fetch (Figure 10.17).
Figure 10.17. Most ocean swells originate in the southern oceans where strong winds combine with unlimited fetch.