STATE AGRICULTfJRAL SOCIETY. 253 



MODIFYING CAUSES OF THE CLIMATE 



PACIFIC COAST OF THE UNITED STATES AND BRITISH COLUMBIA. 



FURNISHED SERGEANT JAMES A. BARWICK, SIGNAL CORPS, U. S. A., SACRA- 

 MENTO, CALIFORNIA, BY DR. J. B. TREMBLEY OF OAKLAND. 



It is said that every country in tlie world, to a greater or less extent, 

 has a climate peculiar to itself. In many respects it may be similar 

 to that of another, but not identical, for the various factors that go to 

 make it are not always equally alike, or bring the same influences to 

 bear on each individual region of the earth. It was once thought 

 that climate depended mostly on latitude and the declination of the 

 sun either north or south of the equator; but more recent observa- 

 tions show that many other causes which are independent of these 

 modify temperatures and precipitation. 



The western coast of Europe and North America are examples of 

 similar climate, modifled by the same corresponding causes, ocean 

 and air currents. Without entering into an extended inquiry over 

 the various portions of the world in comparing climatic factors, which 

 would be uninteresting to a majority of readers and embrace more 

 than is designed to be written in this paper; therefore, the knowledge, 

 positive and theoretical, of the climatic conditions that are imposed 

 upon the western slope of the Pacific Coast, bordering on the ocean, 

 from Alaska towards the south, and the causes as far as observed, is 

 all that would interest the local or general reader. The same general 

 causes that modify the climate of Alaska, British Columbia, Oregon, 

 and California, extending into Mexico, have long been known to 

 meteorologists and those who have made physical geography a study. 

 But the many local modifying influences that these great currents of 

 water and air meet with, as they impinge upon the northwestern 

 coast of the continent, by high mountain ranges, inland valleys, and 

 solar heat, gives as various climates as the topography of the country 

 is diff'erent where their influence is felt. The ocean current that 

 modifies the climate of the Pacific Coast is a portion of the great 

 equatorial current which is deflected northerly and easterly when it 

 meets the eastern coast of Asia. This current, a portion of the warm 

 equatorial current, as it flows toward the northwest, washing the 

 eastern shores of China and Japan, takes the name of the Japan 

 current, or Kuro-Siwo. At or near latitude 50° and longitude 170°, 

 it divides; one portion, continuing northerly, passes through Behring 

 Straits, the other south of the Aleutian Islands assumes the name of 

 the Aleutian current. It advances eastward until it strikes the north- 

 west coast of North America; then, turning acutely to the southeast, 

 flowing along the western shore, until what is left is drawn into the 

 great equatorial current at or near the Tropic of Cancer, again to 

 make the circuit of nearly a quarter of a hemisphere. Various ele- 



