Wavelength (water waves)

Geometry of a trochoidal deep water wave: To define the wavelength, the calm water level, the wave height, the horizontal and the vertical wave asymmetry.

In water waves, the wavelength (symbol ) is the sum of their unequal partial lengths of the ridge area and the valley area related to the calm water level (see also the adjacent picture) ${\displaystyle L}$

${\displaystyle L_{\mathrm {B} }}$< and ${\displaystyle L_{\mathrm {T} }}$ ${\displaystyle \qquad }$

${\displaystyle L=L_{\mathrm {B} }+L_{\mathrm {T} }}$ .

Since the phase velocity of the normal dispersion is subject to and with decreasing water depth also decreases, meets latter also to the wavelength. In contrast to electromagnetic waves, gravity waves differ in shape from the regular cosine shape in such a way that they are both horizontally and vertically asymmetrical. Both the horizontal asymmetry and the vertical asymmetry increase with decreasing water depth towards the coast. At the same time, the front slope of the wave crest becomes steeper than the rear until the wave breaks. ${\displaystyle c}$ ${\displaystyle \mathrm {d} c/\mathrm {d} L\leq 0}$ ${\displaystyle d}$ ${\displaystyle L_{\mathrm {B} }<L_{\mathrm {T} }}$ ${\displaystyle H_{\mathrm {o} }>H_{\mathrm {u} }}$