CONCLUDING REMARKS 



In this " Study of the Radiation of the Atmosphere," I have at- 

 tempted an investigation of the influence of various factors — 

 humidity, temperature, haze, clouds — upon the radiation of the atmos- 

 phere. The results of these investigations are briefly summarized at 

 the beginning of the paper. 



It may be of advantage here to state in a few words in what 

 respects this study must be regarded as incomplete and in need 

 of further extended investigations. In the first place, it will be 

 noticed that my observations have been limited to a particular time of 

 year; the observations in Algeria and in California have all been 

 made during the periods July-August of the years 1912 and 1913. 



Now the investigations, as yet unpublished, carried on at the 

 Physical Institute of Upsala, indicate that the amount of ozone 

 contained in the atmosphere is larger in winter time than in summer 

 time. Further, it has been shown by K. Angstrom ' that the ozone 

 has two strong absorption bands, the one at A = 4.8 /a, the other at 

 A = 9. 1 to 10 p, of which the latter especially is situated in a region of 

 the spectrum where the radiation of a black body of the temperature 

 of the atmosphere ought to have its maximum of radiation. Then 

 it is obvious that the radiation of the atmosphere must be dependent 

 also upon the quantity of ozone present. Spectroscopic investiga- 

 tions indicate that in the summer time the ozone present in the air 

 is practically nil; it is therefore not liable to have introduced any 

 complications into the results discussed in this paper. But in the 

 winter the quantity of ozone is often considerable, and it is not im- 

 possible that the variations of the effective radiation in the winter 

 may be partly due to variations in the quantity of ozone in the 

 upper air layers. The consequence of the higher radiating power 

 of the atmosphere, due to the presence of ozone, must be that the 

 effective radiation ought to be found to be less in the winter than 

 is to be expected from the observations discussed in this paper. 



Another point where it is desirable that the observations of the 

 " nocturnal radiation " should be extended, is in regard to conditions 

 under which the quantity of water in the air is very small. Such 



1 K. Angstrom : Arkiv fur Mat., Astr. och Fysik I, p. 347, 1904. Ibidem, I, p. 

 395, 1904. 



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