no. 3 



RADIATION OF THE ATMOSPHERE ANGSTROM 



79 



the computed data, for the effective radiation as a function of the alti- 

 tude. The curves bring out some interesting facts that deserve 

 special consideration. 



For ordinary values of the humidity, the effective radiation has a 

 maximum at i to 4 km. altitude. 



An increase of the humidity or a decrease of the temperature 

 gradient shifts this maximum to higher altitudes. 



The . effective radiation gradient is consequently positive at low 

 altitudes and negative at high altitudes. 



An examination of the observations, made simultaneously at dif- 

 ferent altitudes, must naturally give a result that is in general accord- 

 ance with these considerations, which are based upon the experi- 

 mental investigations. 



Table XIIIa 



In table XIIIa I have collected the data, gained simultaneously 

 at different altitudes during the Mount Whitney expedition. The 

 values represent mean values during entire nights. They confirm 

 the fact, already deduced from more general considerations, that 



