Tables 1 73-1 76.-SOLAR ENERGY. 



TABLE 173. — The Solar Constant. 



i8i 



Solar constant (amount of energy falling at normal incidence on one square centimeter per 

 minute on body at earth's mean distance) = 1.932 calories = mean 696 determinations 1902 — 12. 

 Apparently subject to variations, usually within the range of 7 per cent, and occurring irregularly 

 in periods of a week or ten days. 



Computed effective temperature of the sun: from form of black-body curves, 6000° to 7000° 

 Absolute ; from Ama.\. = 2930 and max. = o.470/x, 6230° ; from total radiation, J = 76.8x10-1''' X T*, 

 5830°. 



TABLE 174. — Solar spectrum energy (arbitrary units) and Its transmission by tbe earth's atmosphere. 



Values computed from em= Coa'", where Cm is the intensity of solar energy after transmission 

 through a mass of air m; m is unity when the sun is in the zenith, and approximately = sec. 

 zenith distance for other positions (see table 180); eo=the energy which would have been ob- 

 served had there been no absorbing atmosphere; a is the fractional amount observed when the 

 sun is in the zenith. 



0.30 

 •32 

 •34 

 •36 

 • 38 

 .40 

 .46 



•50 

 .60 



1. 00 



I. so 

 2. 00 



Transmission coef- 

 ficients, a. 



(.380) 

 560 

 690 

 733 

 779 

 858 

 886 

 922 

 938 

 912 



I* 



(.460) 

 .520 

 .580 



•635 



.676 



.729 



.832 



.862 



.900 



.950 



.970 



.980 



.976* 



.970* 



(.550) 

 61S 

 692 

 741 

 784 

 809 

 887 

 919 

 940 

 964 

 976 

 975 

 96s 

 932 



562 

 768 

 829 

 850 

 866 

 903 

 91S 

 941 

 ,961 

 940 



Intensity Solar Energy. ^UnJ,''"^ 



Mount Wilson. 



25 



58 

 '35 

 192 

 239 

 302 



S'4 

 522 



454 

 346 



258 



61* 



34 



62 



205 



248 

 268 

 268 



221 



147 



19' 



Washington. 



'34 

 232 

 426 

 44' 

 393 



3'2 



236 

 '53 

 59 

 23 



5' 

 130 



294 

 323 

 306 

 268 

 209 

 141 

 55 



73 

 203 

 237 

 238 

 230 

 185 

 '30 

 52 

 19 



140 

 '74 

 185 

 '97 

 164 

 120 

 49 

 17 



3 

 13 



67 



94 

 112 



145 

 145 

 102 

 43 

 14 



Transmission coefficients are for period when there was apparently no volcanic dust in the air. 

 * Possibly too high because of increased humidity towards noon. 



TABLE 175. 



The Intensity of Solar Radiation In different sections of the spectrum, ultra-violet, visual 

 infra-red. Calories. 



TABLE 176. — Distribution of brightness (Radiation) over the Solar Disk. 



(These observations extend over only a small portion of a sun-spot cycle.) 



^ Taken from vols. II and III and unpublished data of the Astrophysical Observatory of the 

 Smithsonian Institution. Schwartzchild and Villiger : Astrophysical Journal, 23, 1906. 

 Smithsonian Tables. 



