4i8 



Tables 649-552.-SOLAR ENERGY. 



TABLI! 549. —Tbe 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 varia.tions, 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. = 0.470JU, 6230° ; from total radiation, J = 76.8x10-1=^ X T*, 



5830°- 



TABLE 550. — Solar spectrum energy (arbitrary units) and its transmission by the earth's atmosphere. 



Values computed from em= Coa"", where em 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 556) ; eo= the energy w^hich 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 651. — The intensity of Solar Radiation in different sections of the spectrum, ultra-violet, visual 



infra-red. Calories. 



TABLE 662. — Bistributlon 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 II and III and unpublished data of the Astrophysical Observatory of the 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 Institutioti. Schwartzchild and Villiger: Astrophysical Journal, 23, 1906. 



'Smithsonian Tables. 



