The veloc I ty of a wave is the rate at which it's 



CRESTS MOVE FORWARD, OR THE VELOCITY EQUALS THE 

 LENGTH DIVIDED BY THE PERIOD. BY APPROXIMATION, 

 THE VELOCITY IN KNOTS NEARLY EQUALS THREE TIMES 

 THE PER lOD IN SECONDS. 



The MAXIMUM length of a wave in THE North Atlantic 



APPEARS TO BE ABOUT I , 600 FEET WHICH CORRESPONDS 

 TO A PERIOD OF ABOUT |6 SECONDS. LONGER WAVES MAY 

 HAVE BEEN REPORTED FOR THE NORTH ATLANTIC, BUT THEY 

 ARE EXTREMELY UNUSUAL AND THE OBSERVATIONS ARE 

 QUESTIONABLE . 



Average size of Atlantic Waves - Waves from 5OO to 



600 FEET IN LENGTH ARE SOMETIMES ENCOUNTERED IN THE 



North Atlantic, but generally they are from I50 to 

 300 feet with periods from 6 to 8 seconds. 



Extremely high waves are occasionally reported for 

 THE North Atlantic, these range up to 60 feet in 



HEIGHT. The very HIGH WAVES ARE USUALLY LITTLE 

 WAVES ON TOP OF BIG WAVES, AND A3 SUCH THEY DO NOT 

 INVOLVE MUCH WATER IN THE PEAK REGION. |N SOME OF 

 THESE "very HIGH WAVES", MUCH OF THE ENERGY IS 

 SPENT IN UP AND DOWN MOTION RATHER THAN FORWARD 



MOTION. Thus, the energy available in these over- 

 sized WAVES which can BE SPENT IN A HORIZONTAL 

 DIRECTION MAY NOT NECESSARILY BE THE SAME TYPE OF 

 FUNCTION OF WAVE HEIGHT AS FOR LOW OR MEDIUM WAVES. 



DISTURBANCE BENEATH SURFACE 



The DISTURBANCE SET UP BY THE WAVE MOTION EXTENDS 



for some distance below the surface, but the size 

 of the orbits, through which the water particles 

 move, decreases rapidly with increase in depth. 

 At a depth equal to one wave length, it is less 

 than a five hundredth part of what it was at the 

 surface, so that water at that depth may be consid- 

 ered undisturbed and any motion associated with the 

 largest ocean waves is inappreciable at even modest 



DEPTHS. 



WAVE EFFECT (N SHOAL WATER 



Waves from deep water are modified as they get into 

 shoal water. when the depth is reduced to less than 

 one-half the wave length the orbit of the particles 



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