318 SOILS: PROPEBTIES AND MANAGEMENT 



Fig. 52. — Diagram showing the proportional amount of heat received to 

 the unit area by different slopes on June 21, at the 42d parallel north. 



It is seen that in this case a southerly slope of 20° 

 receives to a unit area the greatest amount of heat, the 

 level soils and the soils having northerlv inclination of 

 20° differing in the order named. The following table 

 shows the proportional amount of heat received by each 

 one of these soils per unit area at midday with such an 

 inclination of the sun's rays : — 



Proportional Amount of Heat Received per Unit Area 

 BY Different Slopes on June 21, at the 42d Parallel 

 North Latitude 



20° Southerly slope = 106 



Level = 100 



20° Northerly slope = 81 



