Basically, waves have a longer wavelength in deeper water compared to shallow water because waves move faster in deeper water. Waves move faster in deeper water because waves travelling in deep water do not interact with the medium's bottom surface that much, while waves travelling in shallow water will get comparably high impact/resistance from the medium's bottom surface. Hence, wave speed increases in deeper water.
To help your understanding, this is the equation to calculate wave speed:
Wave speed = Frequency * Wavelength
As frequency is a fundamental character of a certain wave, it remains constant even when the medium changes. In deeper water, since frequency remains constant, the wavelength should increase in order to increase the wave speed.
Coming back to the equation, this happens in deeper water:
Hi Thibaud, thank you for your question.
Basically, waves have a longer wavelength in deeper water compared to shallow water because waves move faster in deeper water. Waves move faster in deeper water because waves travelling in deep water do not interact with the medium's bottom surface that much, while waves travelling in shallow water will get comparably high impact/resistance from the medium's bottom surface. Hence, wave speed increases in deeper water.
To help your understanding, this is the equation to calculate wave speed:
Wave speed = Frequency * Wavelength
As frequency is a fundamental character of a certain wave, it remains constant even when the medium changes. In deeper water, since frequency remains constant, the wavelength should increase in order to increase the wave speed.
Coming back to the equation, this happens in deeper water:
(Increased wave speed) = (Constant frequency) * (Increased wavelength)
Does this answer your question?