WEATHER CONDITIONS ON 

 THE PACIFIC COAST 



BY ALEXANDER MCADIE 



Abbott Lawrence Botch Professor of 

 Meteorology, Harvard University 



IT MAY pay us to begin right by realizing that 

 in discussion of the weather, not only of the 

 Pacific Coast, but of any section, we must first 

 free our minds of the impression that we definitely 

 know the causes of those rather abrupt atmospheric 

 changes which we call weather, as distinguished 

 from the slower and more uniform changes which 

 combine to make the climate of a place. 



Scientific men are partly responsible for the 

 confusion that exists regarding cause and eff'ect 

 in weather phenomena; and too much has been 

 advanced regarding the structure of storms, gen- 

 eral and planetary circulation, rainfall distribution, 

 and other problems, based on assumptions which 

 modern soundings in the air are disproving. In- 

 deed we have much to unlearn even in so funda- 

 mental a matter as the distribution of heat. Many 

 instances could be given of explanations published 

 in text books which are inadequate and out-of-date. 

 Then there are numerous popular misconceptions 

 for which scientific men are in nowise responsible, 

 and which are due to press headlines. One of 

 these which is widespread is that the Kuroshiwo, 

 or black current, more popularly called the Japan 

 current,* warms the northern Pacific Coast. This 

 current, even off" the coast of Japan, is only a few 

 degrees warmer than the surrounding water; it 

 fans out into a drift as it moves eastward, and 

 later divides. Except for that return branch known 

 as the California current, the Japan current does 



• The principal currents in the North Pacific are the north 

 equatorial, the equatorial counter- current, the Kuroshiwo, 

 the California current, and the Bering Sea current. The 

 north equatorial flows westward in the region of the trade 

 winds and reaching the islands off th^ Asiatic coast is de- 

 flected northward. The equatorial counter-current flows 

 eastward a little north of the equator. The Kuroshiwo Is a 

 portion of the north equatorial current, passing north of 

 Formosa and southeast of Japan. Leaving the Japanese 

 coast, the current becomes more a drift, fanning out and 

 flowing eastward past the Aleutian Islands, dividing into 

 north and south drifts on the Alaska coast. The California 

 current is that portion of the Kuroshiwo flowing southeast- 

 ward some distance from the Oregon -California coast. Be- 

 tween this current and the shore is a narrow counter-current 

 known as the Davidson current, flowing northward. (See 

 fig. 2.) The California current is colder off the California 

 coast than the water of the Pacific farther west. 



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