THE CLIMATE OF WESTERN CANADA 35 



climates can imagine. These conditions, together with 

 the favorable monthly distribution of precipitation, are 

 largely responsible for the measure of success that has 

 been attained in crop growing in our northern semi-arid 

 climate. 



Fig. 16. Hours of Possible Sunshine Daily in Summer. 



26a. The Effect of Latitude and Altitude on Tempera- 

 ture. Where no other factors interfere the average de- 

 crease in temperature is approximately three degrees for 

 every 100 miles one goes in a northerly direction. It 

 is seldom, however, that this ratio is not affected by 

 changes in altitude or relation to forests or large bodies 

 of water. 



The lowering of temperature as a result of increase 

 in elevation averages one degree for every 300 feet. The 

 effect of latitude and altitude is clearly shown by the 

 height of the permanent snow line above sea level. At 

 the north pole this line is at sea level. At the southern 



