of the air resistance they meet. They will however continue to 

 receive energy by the pulling force of the wind and will grow In 

 height until this gain is compensated by the loss due to air re- 

 sistance, which occurs v\tLen the ratio C/U equals l.k5>' The fetch 

 and duration needed for reaching this stage Increase rapidly with 

 increasing wind velocity, as shown by the values in Table I. If 

 the fetch and the duration are longer than those listed in the 

 table the highest possible waves will be present regardless of 

 how much longer the wind blows. 



Table I 



Highest Possible Waves Produced by Different Wind Velocities, 

 and Corresponding Fetches and Durations. 



(Ratio wave velocity to v/ind velocity equals 1.1+5, 

 ratio wave height to wave length equals 1/45) 



Waves of the character shown in Table I may be present in 

 the trade wind regions and may be approached in the v^resterlies 

 of the southern oceans. In the middle and higher latitudes of 

 the Northern Heiulsphere the fetches are so short that vrith strong 

 winds the wave velocity always remains less than the wind veloc- 

 ity. 



26 



