26 



and wind velocities in tropical storms are not great enough 

 to develop such long periods. 



The summer maximum in the frequency of occurrence of 

 this swell is quite reasonable, for the northern hemisphere 

 summer corresponds to the southern winter when the storms 

 there should be more intense and follow tracks farther to the 

 north. It would accordingly be expected that if this were 

 the source for these waves, the swell would be of greater 

 significance in the northern summer. 



This swell probably arrives about two-thirds of the time, 

 but because it is usually low it is inconspicuous owing to 

 the existence at the same time of local wind waves or more 

 prominent swell from other generation areas. The presence 

 of this type of swell in the summer is particularly evident, 

 since during that season the contributions from other types is 

 at a minimum. The sea breeze, on the other hand, has a greater 

 frequency of occurrence and tends to have greater velocities 

 in summer than in winter. Thus, the wind waves caused by it 

 would tend to obscure the southern swell more often. 



The Palos Verdes Hills lie in the path of the direction 

 of approach of southern hemisphere swell and only occasionally 

 is the swell of importance, even along the Malibu shore. Its 

 arrival along the Redondo-Santa Monica shoreline is negligible 

 and likely non-existent. 

 Tropical Hurricanes 



In the summer and fall, tropical storms are apt to origi- 

 nate in the oceanic area off the coast of Costa Rica. Nine- 

 tenths of these storms travel northwest from their place of 



