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 



