Code 



2 

 3 



4 

 5 

 6 

 7 



TABLE 12 

 Period 

 WMO Code 3155 for recording period of dominant waves 



5 seconds or less 



6 or 7 seconds 

 8 or 9 seconds 



10 or 11 seconds 

 12 or 13 seconds 

 14 or 15 seconds 



Code 



8 

 9 

 

 1 



X 



16 or 17 seconds 

 18 or 19 seconds 

 20 or 21 seconds 

 Over 21 seconds 

 Calm, or period not determined 



Notes 



(1) The period of the waves is the time between the passage of two successive wave 

 crests past a fixed point (it is equal to the wave length divided by the wave speed). 



(2) The average value of the wave period is reported, as obtained from the larger 

 well-formed waves of the wave system being observed. 



39 



