214 



PRINCIPLES OF STRATIGRAPHY 



With increase in the strength of the wind, the length of the 

 waves increases more rapidly than their height ; the former may 

 increase threefold before the latter is doubled. Lieutenant Paris 

 noted, east of the Cape of Good Hope, that during strong westerly 

 storms, extending over four days with remarkable uniformity, the 

 height of the waves rose only from 6 to 7 meters, while the length 

 increase threefold before the latter is doubled. Lieutenant Paris 



i. e., — changed from 18.84 to 33.57. This increase in length 



H 

 means an increase in the velocity of the wave, which may rise to 

 exceed that of the wind itself. The following table shows the 

 mean velocity of the waves compared with that of the wind in the 

 several oceanic bodies (Krummel-42 :6'o) : 



Table showing relationships between mean wave and wind velocities. 



Mean Mean 



velocity of velocity of 



wind in waves in 



meters per meters per 



second second 



Atlantic Trade Wind 5.9 11. 2 



South Atlantic West Wind 10.9 14.0 



Indian Ocean West Wind 12.5 15.0 



Indian Ocean Trade Wind 7.0 12.6 



Chinese Sea 11. 3 11. 4 



West Pacific Region 8.2 12.4 



Relation behveen Length and Height of Wave. This may be 



expressed by the formula — and varies greatly according to 



H 

 the age of the waves. In young waves it may be 10 or less, i. e., 



if the height of the waves is i meter its length would be 10 meters 



or less. As the wave grows the quotient — increases until it 



H 



is 50 or over. The following classification of waves was made by 

 Paris (Kriimmel-42:5'5) : 



Classification of waves. 



