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SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 68 



" Avogadro's Constant and Atmospheric Transparency," Astro- 

 physical Journal, 40, p. 435, 1914. 



" The Transparency of Aqueous Vapor,'' Astrophysical Journal, 

 42, p. 394, 1915; 



" Atmospheric Transparency for Radiation," Monthly Weather 

 Review, 42, p. 2, 1914. (See also Meteorologische Zeitschrift, 6, 

 p. 270, 1914.) 



Amounts of precipitable water. 

 Fig. 15. — Fractional absorption of energy by water-vapor bands. 



From the second of the papers just cited is reprinted figure 14 

 indicating the atmospheric bands between 0.6 and 2.1 /x. Figure 15 

 shows the absorptions produced by the various bands over the regions 

 indicated by the lines at the bottom of figure 14, and table 9 shows the 

 losses which the incoming solar energy sufifers from these absorptions 

 and from scattering in the atmosphere before reaching sea-level. 

 In table 10 will be found the transmission coefficients, a^^ for i cm. 

 ppt. H2O and for zenith passage of solar energy to sea-level (a^^ ) for 

 use in the formula, ex = eo\ jaa\.a^'^^ j "^ for computing the additional 

 losses due to molecular scattering. In this formula w is the ppt. 

 H2O in cm., m the air mass, in terms of the path vertically through 



