Table 139 425 



ABSORPTION OF RADIATION BY WATER VAPOR, 1.3-9,, 



Fowle ' made a series of laboratory measurements on the infrared absorption spectrum 

 of water vapor for wave lengths up to about 22/*. His results for the band 1.3 to 8.0/* 

 and the band 5 to 9/x are tabulated below. The 1.3 to 8.0^ band was investigated using 

 a 60° rock-salt prism; the 5 to 9//. band using a 15° rock-salt prism. The latter gives 

 smaller dispersions and the measurements are more difficult. 



Part A. — Percent absorption by water vapor, 1.3-8.0^. 



Band 



Wave-length interval 



Precipitable water, mm. 



0.08 0.82 



Part B. — Percent absorption by water vapor, 5-9/t. 



Precipitable water, mm. 



TRANSMISSION OF SOLAR RADIATION BY WATER VAPOR, 0.7-2.2^ 



Fowle 1 determined the fractional transmission of energy in the <$> and yp bands by 

 laboratory experiment over short water-vapor paths. By intercomparison with solar 

 spectra, he was able to extend the path length to greater values, and to relate the trans- 

 mission in the </> band to that in other bands as a function of the amount of water vapor, 

 considering only depletion due to selective absorption and neglecting scattering (see 

 Table 145). These values are given in the chart 2 below for various wave-length bands 

 defined as follows: 



Band Wave-length interval (microns) 



a 0.70-0.74 



.8m 0.79-0.84 



P 0.86-0.99 



1.03-1.23 



* 1.24-1.53 



fi 1.53-2.10 



1 Fowle, F. E., Astrophys. Journ., vol. 35, p. 149, 1912. 

 3 Fowle, F. E., Astrophys. Journ., vol. 42, p. 394, 1915. 



(continued) 



SMITHSONIAN METEOROLOGICAL TABLES 



