The most common source of swell is mid-latitude depression. When the wind blows over the ocean, energy is transferred from air to water and waves are generated. Capillary waves represent the initial stage of wave generation. They are the first waves produced by small vortices in a completely flat sea, and they have a very short wavelength. Perhaps the best way of exemplifying the capillary wave is imagining a simple hairdryer, which can switch itself on and off about once a second.
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What are capillary waves?