NORTH ATLANTIC 77 



time along both its northeastern shore and in its southern side ; swells 

 are high for only to 5 percent of the time. 



c. Caribbean. — Swells low only about 56 percent of the time on the 

 average with 84 percent as a maximum, thus considerably less often 

 than in the Gulf of Mexico. Although high swells are no more fre- 

 quent along the south coast of Cuba (3 percent), or in the shelter of 

 the Antillean chain (1 to 5 percent), where the effective fetch for the 

 Trade Winds is negligible, than they are in the Gulf of Mexico, they 

 are reported with 8 to 12 percent frequency by the time the waves 

 generated by the Trades have reached the downwind parts of the Car- 

 ibbean, off the coasts of Colombia, Costa Rica, and Nicaragua, where 

 the Trades have an effective fetch of something like 350 to 375 miles. 



The failure of high swells to develop more often than they do in 

 the northern side of the Caribbean, in spite of the tendency for the 

 tropical cyclones that cross the latter to follow this general track, 

 reflects the rarity of such storms there. The pilot chart shows the 

 tracks of 10 only, as following this particular route, for the month 

 of August, over the period from 1901 to 1940. 



Winter. — The increasingly stormy weather of autumn in high 

 latitudes, with its continuance through the winter, results, as one 

 might expect, in an increase in the average frequency of high seas to 

 50 to 60 percent and more between Newfoundland, Greenland, and 

 the coasts of northern Europe. This stormyness also causes so wide 

 an expansion, from summer to late winter, in the confines of the region 

 where high seas are encountered for more than a very small part of 

 the time that more than 20 percent of the reports for January and 

 February combined have classed the sea as "high" throughout the 

 whole of the North Atlantic down to latitudes 30° to 35° N., except- 

 ing only along the coasts of southern Spain and of northwest Africa 

 in the one side, and along the northeastern United States in the 

 other. 



An interesting illustration of the dependence of the height of the 

 sea on the strength of the wind is also to be seen in the fact that the 

 boundaries of the tonguelike extension, southward and westward in 

 midocean, of the area where a high sea is reported more than 40 

 percent of the time, as shown on plate V, corresponds in general with 

 the limits of the region where gales occur in February with frequency 

 greater than 15 percent, as outlined on the Pilot Chart. 



Another point of interest is that, while in summer the sea is oftener 

 high along the coasts of western Europe than along the eastern United 

 States at corresponding latitudes (p. 75), there is little difference in 

 this respect during the stormy half of the year between the western 

 side of the Atlantic and the eastern. In fact, the sea has been re- 

 ported "high" rather more often from Nova Scotia to the Grand Banks 



