In deep-water areas individual waves within a group move forward through the group faster than the group itself moves. The group form is produced by the interference of waves of different wavelengths (and therefore speeds) as they move forward from their source. New waves form at the rear of the group, lose amplitude as they reach the front of the group, and disappear. The group speed is half that of the individual waves that it comprises.
Subjects: Earth Sciences and Geography — Ecology and Conservation.