Wave Period

The wave period T is the time for one full wave cycle to pass a fixed point, the interval between successive crests, measured in seconds. It is the inverse of frequency and the most stable wave property: unlike height and length, the period of a wave train is conserved as it travels into shallow water and refracts. Period sets the wavelength and celerity through the dispersion relation; in deep water the phase speed is c = gT/(2 pi) and the wavelength is L = gT^2/(2 pi), about 1.56 T^2 meters. Wind seas run roughly 4 to 10 s, swell 10 to 20 s, and tsunamis tens of minutes. Spectral analysis reports the peak period Tp.