CHAPTER XI 

 CLIMATIC RELATIONS 



CLIMATIC features of natural grain regions are, if any 

 difference, more constantly similar than the soil features. 

 For the large prairie regions the general features common 

 to all are : (1) low precipitation ; (2) the large proportion 

 of this precipitation occurring during the summer months ; 

 (3) the character of the precipitation, falling in quick 

 thunderstorms, as a rule, with very few days of mists or 

 fogs ; (4) the great number of clear days of the summer ; 

 (5) extremes of temperature, especially excessive heat in 

 midsummer; (6) high winds; and (7) a comparatively 

 light snowfall. 



271. Climatic extremes. The temperature and total 

 precipitation of these regions, if more evenly distributed 

 throughout the year, as in forested areas, would not be suf- 

 ficient even for cereal crops. However, the seasonal rain- 

 fall is sometimes one half to two thirds of the total for the 

 year. Also certain points having mean-annual tempera- 

 tures little above freezing, and mean- January temperatures 

 little above zero Fahrenheit, have nevertheless mean-July 

 temperatures about the same as those of points in humid 

 regions at much lower latitudes. Great extremes, there- 

 fore, of both temperature and moisture, are the climatic 

 characteristics of prairie and steppe regions, where the 

 most of the world's small grain (excluding rice) is grown. 



272. Conditions in the Chernozem and Great Plains. 

 The following table, taken from another publication 



254 



