78 FREQUENCY OF WAVE CONDITIONS 



of Newfoundland at that time of year (31 to 39 percent) than for 

 the Bay of Biscay, off the mouth of the English Channel, or along 

 the west coast of Ireland (24 to 31 percent) . 



We would leave the reader with only a very pale picture of the 

 actual fierceness of the sea that ships often encounter in high lati- 

 tudes of the North Atlantic, during winter gales, if we were to stop 

 here, for no one, we fancy, who has made many winter crossings during 

 the stormy season would class an 8- or 9-foot sea as a high one at 

 that time for that part of the ocean. Actually, waves of 20 feet or 

 higher have been reported by sailing ships during 13 percent of the 

 time between Newfoundland and England for the year as a whole, 

 for which no doubt the storms of winter are chiefly responsible (p. 77). 

 And waves more than 40 feet high have been reliably reported, not 

 only along this belt where the Westerlies rule, but even as far south 

 as the vicinity of the Azores in the eastern side of the Atlantic, during 

 winter gales of unusual severity, as described above. The data at 

 hand do not afford any further information in this regard, except that 

 it is certainly unusual for the sea to rise much higher than 15 feet 

 or so anywhere in the western side of the Atlantic south of Newfound- 

 land, unless during exceptionally severe gales. And we might remind 

 the reader that tropical cyclones of hurricane force have never been 

 known to develop in the Atlantic in winter. (See Tannehill, 1938, 

 p. 222.) 



Corresponding to the general increase in the frequency of high seas 

 in winter, the area in mid-latitudes where a low sea is reported with 

 frequency as great as 40 percent in August (pi. II) contracts between 

 August and January to February, to a much narrower belt north of the 

 Trades between the latitudes of northern Florida and of the northern 

 Antilles (pi. VI) ; during these months, too, it is less usual to meet a 

 very low sea even there (40 to 54 percent) than it is at the end of the 

 summer (62 to 81 percent). 



A still more striking alteration of this same order also takes place 

 from summer to winter in the western side of the North Atlantic, 

 along the southern margin of the Trade Wind Belt off South America, 

 where the frequency of seas smaller than 2 or 3 feet falls from 40 to 

 80 percent in August to only 10 to 35 percent at the end of the winter ; 

 this alteration, no doubt, reflects the strengthening through the 

 autumn of the Northeast Trade Wind to a winter average of 14 to 16 

 knots, or even higher. But the prevailing height of the sea does not 

 alter much from summer to winter in the eastern part of the Trade 

 Belt, between the Cape Verdes, the Canaries, Madeira, and the coast 

 of Africa, where the average strength of the wind does not change 

 much from the one season to the other (average about 12 to 14 knots 



