EXAMPLES OF REFRACTION 



Various aerial photographs and refraction dia- 

 grams are of interest in providing typical ex- 

 amples. Figures 23 and 24 show refraction 

 diagrams for Little Placentia Harbor, New 

 Foundland. Figure 23 shows waves of 10 second 

 period from NW carried from deep water, on 

 Hydrographic Chart 2376, to the mouth of the 

 harbor. Wave fronts then were transferred to a 

 larger scale chart (chart 5621) and carried into 

 the harbor as shown in figure 24. 



Aerial photographs which show examples of 

 wave refraction often are of value in the prepara- 

 tion of refraction diagrams. With the exception of 

 figure 27 such examples are shown in figures 25-33. 



Figure 25 shows a mosaic prepared from aerial 

 photographs of refraction effects at Half Moon 

 Bay, Calif. Note that the waves are breaking 

 over a submerged reef offshore. 



Figure 26 shows waves which have passed 



through the entrance of Humboldt Bay and into 

 the bay. Note that waves are breaking inside 

 the inlet. This breaking is probably the result 

 of a combination of shoal water and a tidal cur- 

 rent running opposite to the direction of wave 

 travel. Very often in the preparation of a refrac- 

 tion diagram, when waves are carried over a 

 shoal of limited area, the wave crests appear to 

 cross each other. That such a condition can 

 occur is illustrated in the upper right-hand corner 

 of figure 26 where the waves do cross. That a 

 shoal area exists at this locality is shown by the 

 hydrographic chart in figure 27 which covers the 

 section of the bay appearing in figure 26. Note 

 that where the waves cross, they augment each 

 other and breaking results. 



The important features of refraction illustrated 

 by the photos in figures 28-33, inclusive, are 

 indicated in the caption under each photo. 



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