THE CLIMATE OF WESTERN CANADA 21 



the evaporation of the resulting moisture is greater in 

 the prairie areas than in the wooded and semi-wooded 

 parts, and the most frequent melting and greatest 

 evaporation occurs in the Chinook belt of southern Al- 

 berta and southwestern Saskatchewan. 



10. The Form in which the Precipitation Occurs. 

 Precipitation includes all the moisture that falls from 

 the clouds to the earth. Rainfall is the most important 

 but snowfall is also important. Hail and dew are other 

 forms. 



Snowstorms occur earlier than November and later 

 than March, in fact, flurries may occur after tin crop 

 is up or before it is threshed. And snow that falls after 

 March and before November may interfere with farm 

 operations but it always functions as rain so far as the 

 farmer is concerned and is generally very much ap- 

 preciated by him when it comes in the spring. 



The snowfall generally ranges between 30 inches and 

 60 inches per year, although less than 15 inches was re- 

 ported twice at Battleford and more than 80 inches 

 twice at Winnipeg. The area of lowest average snow- 

 fall runs in a northwesterly direction from southeastern 

 Saskatchewan to northeastern Alberta, including Arcola, 

 Regina, Saskatoon and Battleford. The amount in- 

 creases rapidly in a northeasterly direction from this 

 area but less rapidly in a southwesterly direction until 

 western Alberta is reached. It has already been pointed 

 out that from 50 to 60 per cent, of the total precipita- 

 tion falls as rain in the May-August period, and that 

 April, September and October precipitation is chiefly 

 in the form of rain. In the prairie area any snow that 

 falls in October usually melts in a few days but it has 

 been known to remain on the ground from the early 



