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When wind blows over the sea, it excites a range of wavelengths.

Why do longer wavelengths travel faster?

veronika
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1 Answers1

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Definitions

  • deep water limit : when the wavelength of the mode/wave is much less than the depth of the water
  • shallow water limit : when the wavelength of the mode/wave is much larger than the water depth

Answer

Why do longer wavelengths travel faster?

In the deep water limit, the phase speed of, say, a gravity wave is $V_{ph} \propto \sqrt{\lambda}$, where $\lambda$ is the wavelength. This is because the waves are dispersive, i.e., their frequency depends upon their wavenumber/wavelength.