NO. IO 



REFLECTING POWER OF CLOUDS — ALDRICH 



the mean of a number is used, the error from irregular drift is 

 minimized. The writer is inclined to place more weight in the obser- 

 vations of the first half of the morning, for the fog then was thicker 

 and its top surface more level. As the sun rose higher there was not 



3 



fl -3 S 7 .& £t .3 S 7 i 



Abscissae = Air masses. Ordinates = Calories. 

 Curve A = Total sky and sun per sq. cm. of horizontal surface. 

 Curve B = Calories reflected from cloud per sq. cm. of horizontal surface. 

 Curve C=Pyrheliometry of September 16. 1918. Total calories from sun 

 alone per sq. cm. normal to beam. 



only more boiling of the fog surface but the increased temperature 

 differences tended to increase possible thermo-electric disturbances. 



RESULTS 

 The mean value is 78 per cent. No evidence of a change of reflect- 

 ing power with a change in solar altitude is evident for the range of 



