If a wave strikes a barrier at a right angle, there is little loss of wave energy. However, such a condition is rare in nature. If two waves of the same wave length are moving in opposite directions, less ideal reflections will produce standing waves.

The particles of water in the waves continue to move vertically and horizontally with no circular motion like in the progressive wave. Standing waves are characterized by lines along which there is no movement.

There may be one or more nodal lines. Antinodes represent the points of maximum vertical movements within a standing wave. The antinodes refer to crests which alternately become troughs.

It is to be borne in mind that the maximum particle movement takes place when the water surface is level. The movement of water particles below the antinodes is vertical only but beneath the nodal line the water moves mostly in a horizontal direction.

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A very good example of reflection of waves is the Wedge that develops west of the 400 meter jetty at Newport Harbour, California. Here the incoming waves reach heights exceeding 8 meters. These waves are very dangerous to swimmers.