NO. 3 RADIATION OF THE ATMOSPHERE ANGSTROM 69 



of mountain regions that do not rise higher than about 10 or 15 

 degrees above the horizon is therefore very small and can be neg- 

 lected. In valley regions the effective radiation must be less than oh 

 a plane, owing to the shading influence of the mountains around. 

 The conditions will, however, be slightly complicated through the 

 superposed radiation from the surface of the mountains themselves, 

 a radiation that is dependent upon the temperature of the heights 

 and the properties of their surfaces (influence of snow). 



