this process as negligible. This really seems to be the case when 

 the generation of Initial waves or wavelets at very lov; wind velo- 

 cities is considered ([18] , [14]). But if we refer to actual ocean 

 waves, we have to regard a certain general profile with all the 

 smaller superimposed waves, including ripples, as a "rough" wavy sur- 

 face, where the "effective frictional forces" are determined not "by 

 viscosity but by the "roughness" of the wave profile. Therefore 

 the possible work done by these effective stresses, T.^ on the 

 v;ave motion may be of the same order of magnitude as the work done 

 by normal components acting on the main wave profile. 



The distribution of the effective stress "ZT^ over the wave pro- 

 file probably depends upon several factors ^roughness, wave form, 

 wind distribution over waves, etc.), all of which may be different 

 under different conditions. If we assume with Sverdrup-Mionk [1] 

 that T^ is constant along the whole wave profile, than in the inte- 

 gral (6) the periodic term would vanish. This means that this force 

 would not do a net amount of work at the horizontal component u 

 (in (4a)) of particle velocity. But the assumption ~C ^ = const 

 seems to be an oversimplification which annuls wind effects of the 

 same order of magnitude as the effects considered with the normal 

 pressure components. Even though it seems very difficult at the 

 present state of knowledge to estimate the accur.ate distribution of 

 Zf along the wave profile, we have to assume that T7 . is different 

 at different parts of the wave. The horizontal stress component may 

 be written 



'Ct = P'^t ^o^ ' 

 where p' is the density of the air, v the wind velocity immediately 



52 



