694 



STATE BOARD OF AGRICULTURE. 



greater on the immodiate lake shores than further inland. Such large 

 bodies of water funiisli nuicli vapor to tlie atmosphere, which is carried 

 upward by convection with each cyclone whicli passes, is cooled, con- 

 densed and precipitated as rain or snow. Tn the laice region the annual 

 rainfall is over thirty inches, while in the Dakotas it is less than twenty 

 inches, — a ditfereuce due partly, at least, to the lake effect. The reason 



CHART VII. -Average annual rainfall in inches. 



for even less rainfall immediately along the shores of the lakes, than 

 in some interior sections, may be the fact that the cooler weather near 

 the lakes in summer does not foster the convectional action and local 

 thunderstorms to the extent that the warmer interior regions do. The 

 average number of tliunderstorms per year at Grand Haven, Mich., is 

 twenty-six, while at Lansing the average is forty-two. The snowfall is 

 considerably greater near the lakes, however, especially along the south- 

 ern coast of Lake Superior and the eastern coast of Lake Michigan. In 

 the former section over one hundred inches of snow usually falls each 



