Table IIO 309 



COMPOSITION OF DRY AIR UP TO ABOUT 25 KILOMETERS 



•Variable: see Carpenter, T. M., Journ. Amer. Chem. Soc, vol. 59, p. 358, 1937. 



Haldane, J. B. S., Nature, vol. 1037, p. 575, 1936. 



Callendar, G. S., Quart. Journ. Roy. Meteorol. Soc, vol. 66, p. 395, 1947. 

 t Variable : increasing with height. 

 t Variable: decreasing with height. 



1 Baxter, G. P., Guichard, & Whytlaw-Gray, Thirteenth report of the committee on atomic weights 

 of the International Union of Chemistry. Journ. Amer. Chem. Soc, vol. 69, p. 731, 1947. 



For composition of the upper atmosphere see: 



Dobson, G. M. B., Proc. Roy. Soc. London, A. Bakerian Lecture, 1946. 

 Paneth, F. A., Gluckauf, E., Proc. Roy. Soc. London, A, vol. 185, p. 89, 1946. 

 Paneth, F. A., et al., The upper atmosphere. Quart. Journ. Roy. Meteorol. Soc, vol. 65, pp. 303- 

 336, 1939. 



Table 111 



INDEX OF REFRACTION OF AIR 



Barrell and Sears ' give the following values for the index of refraction of dry C0 3 - 

 free a air at normal pressure in the visible spectrum: 



Index of refraction 

 15 "C. 20 °C. 



1.0002763 1.0002716 



1.0002771 1.0002724 



1.0002779 1.0002731 



1.0002787 1.0002739 



1.0002795 1.0002747 



1.0002799 1.0002751 



1.0002806 1.0002758 



1.0002810 1.0002762 



Barrell and Sears found for the index of refraction of moist normal air in the range 

 10-30 °C, 720-800 mm. Hg. 



(n - 1)10-= [ 0.378125 + °- Q0 g 414 + 0m f 79 ^ X 



P\ 1 + (1.049 -0.0157Q/>X 10^ r f 00624 _ O000680] ___ j____ 

 1 + 0.003661* L ' X a J 1 + 0.003661/ ' 



where X is the wave length of the radiation, t is the air temperature in °C, p is the 

 barometric pressure and / is the vapor pressure, both measured in millimeters of mercury. 

 The variation of the index of refraction n with density p is best represented by the 

 Lorenz-Lorentz * formula 



n 2 — 1 



— — ; — — = constant 



(n' + 2) P 



For a study of the index of refraction of air in connection with microwave frequencies 

 see: Committee on Propagation, Wave Propagation Experiments, Summary Technical 

 Report of NDRC, vol. 2, 1947. 



1 Barrell, H., and Sears, J. E., The refraction and dispersion of air for the visible spectrum, Phil. 

 Trans. Roy. Soc. London, A, vol. 238, pp. 1-64, 1939. 



a See Barrell and Sears for evaluation of small correction necessary due to C0 2 . 

 'Wave length in normal, dry air at 760 mm. Hg. and 15 °C. 

 * Lorentz, H. A., Collected papers, vol. 2, The Hague, 1936. 



SMITHSONIAN METEOROLOGICAL TABLES 



