WAVE STAFF 



wave meter — An instrument used to measure and 

 record wave heights. 



wave of translation — A wave in whicli the water 

 particles are permanently displaced to a signifi- 

 cant degree in the direction of wave travel. (61 ) 

 {See figure for surf zone.) 



wave period — The time, in seconds, required for 

 a wave crest to traverse a distance equal to one 

 wavelength. (73) 



wave pole — (also called toave staff) . A device for 

 measuring sea surface waves. It consists of a 

 weighted pole below which a disk is suspended 

 at a depth sufficiently dee]3 for the wave motion 

 associated with deepwater waves to be negligi- 

 ble. The pole will then remain nearly steady 

 as if anchored to the bottom, and wave height 

 and period can be ascertained by observing or 

 recording the length of the pole that extends 

 above the surface. See wave recorder. (5) 



wave ray — (or orthogonal) . A line drawn every- 

 where perpendicular to the wave crests on a 

 refraction diagram. (See figure for refraction 

 diagram.) 



wave recorder — An instrument for recording 

 ocean waves. Most wave recorders are designed 

 for recording wind waves, that is, waves of 



periods up to about 25 seconds, but some are 

 designed to record waves of longer periods such 

 as tsunamis, seiches, or tides. See tide gage. 



(5) 



wave refraction — 1. The process by which the di- 

 rection of a train of waves moving in shallow 

 water at an angle to the contours is changed. 

 Tlie part of the wave train advancing in shal- 

 lower water moves more slowly than that part 

 still advancing in deeper water, causing the 

 wave crests to bend toward alignment with the 

 underwater contoui"S. 



2. The bending of wave crests by currents. 

 (61) 



wave signature — The graph of pressure versus 

 time at a jioint as a wave passes over it. 



wave spectrum — 1. In ocean wave studies, a graph 

 showing the distribution of wave heights with 

 respect to frequency in a wave record. (5) 



2. A concept used to describe by mathematical 

 function the distribution of wave energy (square 

 of wave height) with frequency (1/period). The 

 square of the wave height is related to the poten- 

 tial energy of the sea surface so that the spec- 

 trum can also be called the energy spectrum. 



wave staff — See wave pole. 



ACTUAL WAVE CREST-ORTHOGONAL PAHERN 

 FOR WAVES PASSING OVER A CLOCK GLASS 



SHADOWGRAPH FOR WAVES OF MOD- 

 ERATE LENGTH PASSING OVER A CLOCK 

 GLASS 



WAVE REFRACTION — CAUSTIC 



(AFTBI WttCa. IMJT 



181 



