6o8 



Tables 766-769 

 SOLAR RADIATION 



TABLE 766. — The Solar Constant 



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 Amax. = 2930 and max. = 0.470^, 6230 ; from total radiation, J = 76.8x10-^ X T 4 , 

 5830° 



TABLE 767. Solar spectrum energy (arbitrary units) and its transmission by the earth's atmosphere. 



Values computed from e„,= e a"\ where e m 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 table778) ; e =the energy which would have been ob- 

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

 sun is in the zenith. 



Transmission coef- 

 ficients, a 



(.380) 

 560 

 690 

 733 

 779 

 858 

 886 



922 

 938 

 912 



<= -2 



(.460) 



S20 



580 



635 



676 



729 



832 



862 



900 



950 



970 



980 



976* 



970* 



(•S50) 

 6l S 

 692 

 741 

 784 

 809 

 887 

 919 

 940 

 964 

 976 



975 

 965 

 932 



n rt u 

 v v n! 



e C u 



.562 

 .768 

 .829 

 •850 

 .866 

 •9°3 

 .915 

 .941 

 .96. 

 .940 



Intensity Solar Energy ,, .. " 



Mount Wilson 

 (altitude 1675 m) 



34 



62 

 205 

 248 

 26S 

 268 

 221 

 147 



19* 



Washington 

 (sea-level) 



•34 

 232 

 426 

 44i 

 393 

 3'2 

 236 



153 

 59 



5i 

 "3° 

 294 

 323 



306 

 268 

 209 

 141 



55 



19 



73 



203 



237 



238 



23° 



185 



130 



52 



19 



140 

 174 

 185 

 197 

 164 

 120 

 49 

 '7 



3 

 '3 



67 



94 

 112 

 ■45 

 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. t Altitude 44 20 m - 



TABLE 768. — The amount of Solar Radiation in different sections of the spectrum, ultra-violet, 



visual infra-red. Calories 



TABLE 769.— Distribution of intensity (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. 



