188 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1954 



infrared, visible, and near ultraviolet. Thus, during the day the sun- 

 light dissociates molecular oxygen. Partial recombination of tlie re- 

 sulting atoms during the night will involve processes in which light 

 may be emitted. It is of interest to note that the yellow D lines of 

 sodium are quite prominent in the air-glow spectrum, even though the 

 proportion of sodium at its maximum concentration is less than 10"* of 

 the main atmospheric constituents. The intensity of emission is so 

 high that Bates has suggested that an observable enhancement might 

 be achieved by conveying a can of sodium to the required altitude by 

 rocket and dispersing the metal there. A day air-glow has been ob- 

 served by rocket methods at altitudes above 40 km. where scattered 

 light from the lower atmosphere is sufficiently weak. Detailed spec- 

 troscopic observation of this air-glow has not yet been carried out. 



REFERENCES 



1. Wekkes, K., and Wilkes, M. V., Proc. Roy. Soc, A, vol. 192, p. 80, 1947. 



2. HoYLE, F., and Bates, D. R., Terr. Magn. Atmos. Electr., vol. 53, p. 51, 1948. 



3. Stewaet, Balfoue, Encyclopedia Britannica, 9th ed., vol. 16, p. 181. 



4. SiNGEB, S. F., Maple, E., and Bovpen, W. A., Joiirn. Geophys. Res., vol. 56, 



p. 265, 1951. 



5. Gartlein, C. W., Phys. Rev., vol. 81, p. 463, 1951. 



6. Meinel, a. B., Phys. Rev., vol. 80, p. 1096, 1950. 



Reprints of the various articles in this Report may be obtained, as 

 long as the supply lasts, on request addressed to the Editorial and Pub- 

 lications Division, Smithsonian Institution, Washington, 25, D. C. 



