With further development of the waves the effective wind forces 

 become more complicated. They depend upon the stage of development 

 of complex wave motion, and in addition we have to consider effective 

 drag forces. The resistance for the flow of the air over the rough 

 wavy surface is composed of form resistances and frictional stresses. 

 From the sxim of the two a total resistance results, which was called 

 "effective wind stress" [8]. The smaller superimposed waves on the 

 general profile may be considered to act as roughness elements with 

 regard to the air which flows over the general profile of the largest 

 waves (Fig. 10). With reference to a previous paper [8], where an 

 attempt was made to evaluate the effective wind stress under these 

 assumptions, we put 



^eff = P'FY^(Pm)^^ •*• I P'Fs'ire^Cl - P^)V 



- J p'Fs*7r6^*(l - Pn,*)V, (22) 



where 



Y^(PJ = [1.75 + ^^'^ (e-^^ {0.48(B + 0.6) 



"^m ^3 



- 0.6 (1 + ^^)] + 0.126)].10"3 (23) 



has the meaning of a resistance coefficient or friction coefficient 

 depending on p. The factors of proportionality s' and s* are assumed 

 to be constant, and s' = s/2, s* = 2s, where s = 0.095 as defined 

 by (16). 



^eff ^^ ^^^ effective resistance of the rough wavy sea surface 

 per area F = b'A , and p^* means the ratio (r /v = 1.37, 6 * the 

 steepness for fully developed "6 ♦-waves" with this ratio p ♦(see 

 Chapter I). Correspondingly ^^ is the ratio (T /v for fully developed 

 "pjj^-waves", as explained in Chapter I, and 5 their maximum steepness 



63 



