and higher than 15 ra/sec. They are marked in Fig. 25 by different 

 signs. The observations at a given fetch-parameter scatter over a 

 certain Interval of the ratio (T /<r but there Is a distinct separ- 

 ation between lower and higher wind speeds of such a kind, so that 

 at a given value gx/v , the ratios 0"/0'uj at light winds are higher 

 than at moderate and strong winds. The three curves are the theo- 

 retical relationships between ^ /^ ^ = cp(gx/v ) at 5> 10, and 20 

 m/sec wind velocity. When the fetch parameter has attained a certain 

 value, depending upon the wind velocity, the ratio 6" /c or T/T 

 becomes unity. That means that these waves have attained their maxi- 

 mum value of 6" or T as given by (T „ or T„ for the 3 -wave in the 



° *' m m "^m 



fully developed state. 



Fig, 26 represents a comparison of measured wave heights H at 

 different fetches and wind velocities with computed heights using 

 the dimensionless form gH/v = (^(gx/v ). At low fetch parameters the 

 computed heights appear a little too high compared with the observa- 

 tions, but it must be kept in mind that the computed values for the 

 stage p<l/3 are maximum values. By the empirical relationship 

 6 = 2p = 0,124 (equation (I8)), the steepness of the waves in their 

 earliest stages of development probably has been assumed a little too 

 high (the value 2p = 0.10 seems to be more representative). But these 

 early stages of wave development are only of minor significance with 

 respect to the later development of the sea. * 



♦Supplement after completion of this report: New observations by U, 

 Roll [25] also Indicate a very rapid Increase of wave steepness at 

 very low fetches, similar to the broken curve of Fig, 12 of this re- 

 port, and in agreement with the observations of the "Heldberg" at low 

 p-values. Probably it would be a better approximation to use the 

 broken curve in Fig. 12 when considering the relationship 6 = f(p). It 



12^ 



