no. 3 



RADIATION OF THE ATMOSPHERE ANGSTROM 



65 





tion is concerned. But in regard to the radiation to points near the 

 horizon we must consider that the corresponding air masses become 

 very large and that effects of dust and haze and other sources of 

 lack of homogeneity in the air must be introduced in quite a marked 

 way. 



Zenith distance. 

 Fig. i i a. — Radiation to different parts of the sky. Bassour observations. 



The curves in figures iia and iib represent the effective radiation 

 within the unit of the solid angle in different directions from a sur- 

 face perpendicular to the radiated beam. From these curves we can 

 compute the radiation from a horizontal surface, like the earth's 

 surface, to the different zones of the sky. If the radiation within a 

 solid angle one degree square is R } the radiation (/) to the whole 

 zone, whose width is one degree, is expressed by : 



J = R cos c/> sin <f> • 360 (1) 



