THE CLIMATE OF MICHIGAN. 



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With the oucoming liigh area, if it advances from the northwest, the 

 winds are northwesterly. With a good aneroid barometer and wind 

 vane the movement and passage of these atmospheric formations can 

 be determined and followed Avith interest and profit, for they largely 

 control weather changes. 



^^Ke: Sqpe(?ior 



CHART X. -Prevailing wind direction. Arrow- 

 fly with the wind. 



HUMIDITY. 



The amount of moisture in the atmosphere in the form of vapor is 

 important enough to be classed in with the other climatic elements. It 

 is usually expressed in terms of relative humidity, or the per cent of 

 moisture present in the air, compared witli the possible amount. The 

 capacitj^ of the air for moisture increases rapidly Avith the temperature. 

 For example the invisible vapor necessary to saturate air at 40° F. is 



