The following terms are used to describe a water wave:

Crest?the highest elevation above the undisturbed sea surface.

Trough?the lowest depression below the undisturbed sea surface.

Wavelength?the distance between two successive crests or two successive troughs.

Wave height?the vertical distance from the top of the crest to the bottom of the trough.

Amplitude? the distance from either the crest or the trough to the undisturbed water level; one-half the wave height.

Period?the time required for two successive crests (or troughs) to pass a given point. Label the parts of a wave on the following sketch.