phase speed

Phase speed, also known as wave velocity, refers to the speed at which a wave's crest or trough travels. This speed is determined by the wave's wavelength and frequency. For surface gravity waves, the phase speed is influenced by both water depth and wavelength. Longer waves travel faster than shorter ones in deep water, a phenomenon called dispersion. In shallow water, where the depth is less than one-twentieth of the wavelength, waves travel faster in deeper water, and their speed is directly proportional to their period. The energy of a wave is proportional to the square of its amplitude, and the speed at which this energy or information travels is called group velocity, which can differ from the phase speed.12