SUNLIGHT AS A SOURCE OF HADLATION 



103 



Toiiscy (1952) of the Naval Research Laboratory with a sportrosraph 

 on a rocket flying above the ozone region from al)()ut 60 to 110 km on 

 June 14, 1949. The spectra of Figs. 3-1 and 2 overlap at the absorption 

 band 2882 A. 



The curves of Pettit and the NRL (Durand and coworkers, unpub- 

 lished; cited in Hulburt, 1947) shown in Fig. 3-3 in the ultraviolet, are 

 replotted in Fig. 3-4 with the ordinate on an absolute scale and with the 



120 



no - 



PETTIT, 1940 



NAVAL RESEARCH 

 LABORATORY, 

 55KM, 1947 



STAIR, 1951- 



6000°K 

 RADIATION 



J L 



2500 



3500 



3000 

 WAVE LENGTH, A 



Fig. 3-4. Ultraviolet portion of the solar spectrum on top of the atinospliere. 



scale of the abscissa expanded over that of Fig. 3-3 in order to bring out 

 detail. The data of Stair (1951) of October 1950 are added. The fluc- 

 tuations in the curves indicate certain major absorptions in the solar 

 spectrum but are not fine-grained enough to bring out all the Fraun- 

 hofer lines. Pettit's value of u at 3400 A is taken as standard, and the 

 other two curves are adjusted to it. The ()000°K black-body curve of 

 Fig. 3-3 is continued in Fig. 3-4 to emphasize the fact that the solar 

 intensity continues to fall below it as the wave length is decreased to 

 2200 A. 



In the infrared beyond 2.6 n, io decreases rapidly with increasing wave 

 length approximately as for a black body at 7000°K. For example, rela- 



