An example of refraction is when waves approach a straight shoreline at an angle. The part of the wave crest closer to shore is in shallower water and moving slower than the part away from the shore in deeper water. The wave crest in deeper water catches up so that the wave crest tends to become parallel to the shore. Wave refraction also occurs around a circular island. The wave approaching from one direction will wrap around the island so the wave crest will approach the beach close to parallel on all sides of the island (figure 3) (1). In Figure 2, the wave crests are shown (the first crest is a horizontal line at the top of the figure), and the vertical lines are wave orthogonals (lines which would be traced out by following the wave direction). Note the criss-crossed wave pattern behind the island. Figure 2. Plan view of wave refraction around an island. Waves approach the circular island from the top of the figure. From Bascom, 1964. Diffraction usually happens when waves encounter surface-piercing obstacle, such as a breakwater or an island. It would seem that on the lee side of the island, the water would be perfectly calm; however it is not.
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- Winter '16
- Bula Vijj
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