the expected number of waves per second. This may be expressed as follows: 



E»pec4reA r^umtet- o4 xeroa per sec.-^ 



fro'-i t-Thich is obtained the 



JJ^^ f^{s.) a^ 



f ^^4-^ A^ 



(lA) 



Ex^ecTed YMAm\5er o-f vjaves per iec,«- 

 Substituting -|- s \ / T i equation (I3) becomes 



Expecbd YiumWr c[ vjcxves per sec = 



1 



.^aA 



-t- /\V)^-?- 



\ ^^i)<lf 



Va 



(13) 



r 



T" 

 Jo 



' K'CT) AT 



ll>- 



* ffCT) if 



04) 



The reciprocal of this expression gives the average period 



T = 



\^ t''''k'ctWt 





Neumann (1953) obtained an empirical spectrum for a fully-developed 



wind -gene rated sea. 



A (yW.) = c^ e 



where v is the wind velocity. If Neumann's spectrum is applicable, 

 equation (15) can be written 



T =. 



frV-^-^V 





/ft 



(It) 



17 



