I902. 



FORESTRY AND IRRIGATION. 



421 



CLIMATIC DATA FOR MARQUETTE, MICHIGAN. 



dominating characteristic of the weather 

 in the white pine belt. 



When we extend our view of the 

 weather so as to include a longer period 

 of time, say a month, it then becomes 

 possible to reduce our mental concept 

 to numerical values. In the course of 

 man}' years an approximate value for 

 the mean temperature is determined ; so 

 also for the total precipitation, the aver- 



age cloudiness, and other climatic ele- 

 ments. Thus we are able not only to 

 form a clear idea of the climate of any 

 one place, but also to compare climates 

 and to note the distinctive features of 

 one as compared with those of another. 

 The United States Weather Bureau, 

 of the Department of Agriculture, has 

 been making observations at a few 

 points within the white pine belt during 



CLIMATIC DATA FOR ALPENA, MICHIGAN. 



