TABLES 1 73-1 76. -SOLAR ENERGY. l8l 



TABLE 173. 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 = 76.8x10-1* X T 4 , 

 5830. 



TABLE 174. Solar spectrum energy (arbitrary units) and its transmission by the earth's atmosphere. 

 Values computed from e m = e a m , 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 table 180) ; e =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. 



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 II and III and unpublished data of the Astrophysical Observatory of the 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. 



