fetch area into a region of calm or into a region where the wind 

 velocity is small compared to the wave velocity, the waves naturally 

 meet an air resistance. Due to this air resistance a loss of energy 

 takes place and a decay of waves will be observed. In certain cases, 

 turbulence may play an \inimportant part in damping the wave motion, 

 or may be absent altogether, which happens perhaps when the waves 

 travel through a region of smooth sea. But this fact does not ex- 

 clude the significance of eddy viscosity when the waves are growing 

 in the wind area or when they are maintained by wind action. In 

 this case, the turbulent sta te of real "w i nd sea " and the energy 

 dissipation by eddy viscosity is not to be neglected in the energy 

 budget. Similarly, eddy viscosity has to be taken into account 

 when considering the decay of waves (swell), if the waves travel 

 through a region of turbulent sea. 



Wind generated waves present themselves to the observer as a 

 series of more or less "hill-like" irregular crests separated by 

 intervening troughs. The formation of the typical "short-crested 

 wind -waves" may be explained partly by the turbulence of the wind 

 and the different wind pressures on the windward and leeward slope 

 of the wave profile. In any event, it is to be expected that irregu- 

 larities of the air current counteract the formation of long-stretched 

 wave crests. This especially seems to be the case where very "young 

 sea," with rather short wave lengths, but characterized by a great 

 steepness, is generated. If once arisen, these shortcrested waves 

 will themselves disturb the air motion and react on the state of 

 atmospheric turbulence over the sea surface. On the other hand, 

 especially in stormy weather, the fully developed sea with its 



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