84 FREQUENCY OF WAVE CONDITIONS 



boundary of the Trade Wind Belt is separated from the coasts of 

 southern and of Lower California by a belt some 300 miles wide at its 

 narrowest, with the coasts of Central America fronting on the Dol- 

 drum Belt, where the winds are not only variable, but as a rule weak. 

 Available information for summer also makes it likely that a smooth 

 sea is equally characteristic along the equatorial belt in the 

 western half of the Pacific, though the reports received thence were 

 not numerous enough to have much statistical value. And more fre- 

 quest reports of low seas westward along the Northeast Trades 

 from about the longitude of Wake Island and of the Marshalls, than 

 eastward, accord with the wind distribution at this season. It is 

 doubtful, however, whether there is any clear parallel in the North 

 Pacific to the smooth belt along the belt of Variables that is so con- 

 spicuous a feature of the sea pattern of summer in the North Atlantic 

 (p. 74). Perhaps as good an illustration as any of the contrast be- 

 tween the summer seas of the two oceans in this last respect, is that the 

 general August average between latitudes 25° and 35° N. is about 52 

 percent low and about 8 percent high for the North Pacific west of the 

 longitude of western Alaska, but about 67 percent low and only to 4 

 percent high for the North Atlantic west of about longitude 35° W. 



Ten of the 19 reports received from the southern part of the Sea 

 of Okhotsk for July and August (we have no information from its 

 northern part) described the sea as "low," none of them as "high," 

 which is in agreement with the fact that gales of force 8 or stronger 

 are so uncommon, at that time of year, over the waters between 

 Kamchatka and the Asiatic coast that their percentage is shown as 

 zero there on the Pilot Chart for August. 



The summer seas run low rather more commonly in the Sea of 

 Japan (41 to 80 percent according to locality) than in the Sea of 

 Okhotsk, nor is a high sea reported at all there in August and only 

 occasionally (0 to 5 percent) in July. And the state of the sea is 

 much the same as this in the Yellow Sea. It rises high rather more 

 often, however, in summer in the South China Sea (0 to 14 percent 

 frequency), due to the gales that sometimes blow there and to the 

 occasional typhoons that cross its northern half; the Hydrographic 

 Office Pilot Chart for August gives frequencies of 1 to 4 percent for 

 gales for the South China Sea as a whole and shows the tracks of 4 

 typhoons crossing its northeastern part. But the sea has been classed 

 as "low" in 94 to 100 percent of the August reports from the waters 

 between the southern Philippines, Borneo, and Celebes, nor do they 

 mention a high sea at all, ordinary gales and typhoons alike being 

 unknown there. 



In a general way, the summer swell is most often high in the parts 

 of the North Pacific where the sea is most often high, and low where 



