RADIUS OF MAXIMUM WINDS - Distance from the eye of a hurricane, where 

 surface and wind velocities are zero to the place where surface 

 wind speeds are maximum. 



RAY, WAVE - See ORTHOGONAL. 



RECESSION (of a beach) - (I) A continuing landward movement of the 

 shoreline. (2) A net landward movement of the shoreline over 

 a specified time. Also RETROGRESSION. 



REEF - An offshore consolidated rock hazard to navigation with a least 

 depth of 10 fathoms (about 20 meters) or less, 



REEF, ATOLL - See ATOLL. 



REEF, BARRIER - See BARRIER REEF. 



REEF, FRINGING - See FRINGING REEF. 



REEF, SAND - Synonymous with BAR. 



REFERENCE PLANE - See DATUM PLANE. 



REFERENCE STATION - A place for which tidal constants have previously 



been determined and which is used as a standard for the comparison 

 of simultaneous observations at a second station; also a station 

 for which independent daily predictions are given in the tide or 

 current tables from which corresponding predictions are obtained 

 for other stations by means of differences or factors. 



REFLECTED WAVE - That part of an incident wave that is returned seaward 

 when a wave impinges on a steep beach, barrier, or other reflecting 

 surface . 



REFRACTION (OF WATER WAVES) - (1) The process by which the direction of a 

 wave moving in shallow water at an angle to the contours is changed. 

 The part of the wave advancing in shallower water moves more slowly 

 than that part still advancing in deeper water, causing the wave 

 crest to bend toward alignment with the underwater contours. (2) 

 The bending of wave crests by currents. (See Figure A-5.) 



REFRACTION COEFFICIENT - The square root of the ratio of the spacing 



between adjacent orthogonals in deep water and in shallow water at 

 a selected point. When multiplied by the SHOALING FACTOR and a 

 factor for friction and percolation, this becomes the WAVE HEIGHT 

 COEFFICIENT or the ratio of the refracted wave height at any point 

 to the deepwater wave height. Also the square root of the ENERGY 

 COEFFICIENT. 



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