MISCELLANEOUS TABLES. IxXXV 



double weight to those lo' in deviation apart. It will be noted that the summa- 

 tion includes the following spectral bands, namely, below 0.346/^, between 0.346 

 and o.405fi, between 0.405 and 0.704/x, and above 0.704/i, ; or the short-wave 

 ultra violet, the long-wave ultra violet, the visible radiation, and the infra-red 

 radiation. The percentage of the energy included in each of these sections 

 to the total energy is given, and the percentage of the total to the total before 

 it enters the atmosphere, or the atmospheric transmission corresponding to 

 the conditions as specified, is also given. 



By means of computations such as are given in Table iii the curves of 

 Figure i, showing the depletion by scattering in passing through dry air, 

 curve I, and through air containing different amounts of moisture, curves 2 

 to 8, and the depletion by both scattering and absorption, curves 9-15, have 

 been constructed. The ordinates give atmospheric transmission ; the abscissas, 

 air masses, m, corresponding to zenith distances of the sun 0°, 60°, 70.7°, 

 and 75.7°. The values for m less than i represent depletions at elevations 

 above sea level. 



For a more complete description of this figure see the Monthly Weather 

 Review, 55 : 167, 1927, and 56: 394, 1928, and 58: 43, 1930. 



Abbot's correction for u. v. radiation below 0.346/^, which is not mea- 

 sured, includes the radiation absorbed at these wave lengths by an average 

 amount of atmospheric ozone, but does not take account of variations in the 

 ozone content of the atmosphere. Fowle ^ has shown that the absorption by 

 ozone in the visible spectrum varies in amount with both time and place, and 

 that it causes a depletion of solar radiation by about 0.2 to 0.4 per cent of the 

 solar constant. This depletion has not been included in "Absorption by perma- 

 nent gases," near the bottom of Table 112. The values of atmospheric trans- 

 mission in the last line of the table are therefore too high by from 0.2 to 0.4 

 per cent, more or less, depending upon the ozone absorption in the visible 

 spectrum, and disregarding the possible error, probably small in amount, due 

 to variations in the ozone absorption in the ultra-violet. 



Example of the use of Figure i. The atmospheric pressure is 76.0 cm., 

 the water vapor pressure 0.87 cm., the zenith distance of the sun is 60° 

 (ni = 2.0), and the elevation of the station is only slightly above sea level. The 



precipitable water = 2.3X0.87X 10 ^^''"o =2.0 cm. From Figure i the trans- 

 mission read from curve 11, for m = 2, is 0.653. 



T , ,-7 , • , , , TABLE 1 12. 



Table 11 2. International meteorological symbols. 



The information under this heading has been compiled for the present 

 edition by the librarian of the United States Weather Bureau, and repre- 

 sents current practice in the use of the symbols approved by the Interna- 

 tional Meteorological Organization. For further information on the sub- 



1 Fowle, F. E. Atmospheric ozone : Its relation to some solar and terrestrial phe- 

 nomena. Smithsonian Misc. Coll., vol. 81, No. Ii, 1929. 



