724 



TABLE 816.— THE BIOLOGICALLY EFFECTIVE COMPONENT OF ULTRAVIOLET, 

 SOLAR, AND SKY RADIATION PER MONTH PER CM 2 (UVQ IN WATT 

 MINUTES) AND THE TOTAL SOLAR AND SKY RADIATION (Q IN 

 CALORIES PER MONTH PER CM 2 ) INCIDENT IN WASHINGTON, 

 D. C, 1941-1946, MONTHLY AVERAGE 253 



UVQ m Q 



watt min cal 



Month month" 1 cm" 2 month- 1 cr 



Jan 112 4,982 



Feb 209 6,987 



Mar 466 10,847 



Apr 692 12,916 



May 990 15,203 



June 1.108 16,019 



UVQ Q 



watt min cal 



Month month -1 cm -2 month -1 cm -2 



July 1.091 15,239 



Aug 1.012 14,470 



Sept 721 11,158 



Oct. 406 8,767 



Nov 177 6,085 



Dec 087 4,690 



^Coblentz, W. W., Bull. Amer. Meteorol. Soc, vol. 28, p. 465, 1947. 



TABLE 817.— DURATION OF SUNSHINE* 



* Prepared by G. M. Clemence, U. S. Naval Observatory. For more extensive tables, see "Tables of Sunrise, 

 Sunset, and Twilight," Supplement to the American Ephemeris, 1946. 



TABLE 818.— RELATIVE DISTRIBUTION IN NORMAL SPECTRUM OF SUNLIGHT 

 AND SKY LIGHT AT MOUNT WILSON 



Zenith distance about 50° 



This table is abstracted in modified form from the Annals of the Smithsonian Astrophysical 

 Observatory. The observations, which were visual, made on October 17, 1906, probably represent 

 the most ideal sky conditions on Mount Wilson. 



Place in spectrum (fi) 422 



Intensity sunlight 186 



Intensity sky light 1 194 



Ratio at Mount Wilson 642 



Ratio computed by Rayleigh ... — 

 Ratio observed by Rayleigh .... — 



.457 .491 

 232 227 



986 

 425 



701 

 309 



.566 .614 

 211 191 



395 

 187 



231 

 121 



.660 

 166 

 174 

 105 



102 

 102 

 102 



143 

 164 



246 

 258 



168 291 



316 

 328 

 369 



SMITHSONIAN PHYSICAL TABLES 



