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FURTHER EVIDENCE ON THE DEPENDENCE OF 



TERRESTRIAL TEMPERATURES ON THE 



VARIATIONS OF SOLAR RADIATION 



By C. G. abbot 



Secretary, SmitJisonian Institution 



A former paper on this subject ' showed how the temperatures of 

 Washington, St. Louis, and Helena seem to depend on the rise and 

 fall of solar radiation. Table i of that publication gave a series of 

 dates in all months of the year from the year 1924 to 1935 on which 

 the solar radiation apparently began either to rise or to fall for a 

 succession of several days. In figure 2 (here reproduced as figure i) 

 was shown the opposite average marches of temperature at Wash- 

 ington for 16 days after such opposite changes of solar radiation 

 began. 



On the basis of the evidence contained in this paper, Dr. R. A. 

 Millikan composed, and others, including Dr. K. T. Compton, Dr. I. 

 Bowman, and the Chief of the United States Weather Bureau, signed 

 with him, the following memorandum : 



The work on solar radiation that has been carried on for a considerable number 

 of years under the leadership of Doctor Charles G. Abbot has apparently brought 

 to light good evidence, 



First, that the rate at which radiant energy comes to earth from the sun is 

 not entirely constant but sometimes rises and other times falls through periods 

 of a number of days ; and 



Second, that these rising or falling periods of solar radiation are followed 

 through as much as sixteen days by measurable temperature variations in the 

 atmosphere as determined by ordinary thermometer readings. 



These effects are of so much scientific and practical interest for the problem 

 of predicting at least some elements of the " weather " as much as two weeks 

 ahead that it is our unanimous judgment that there should be not only a continua- 

 tion of this research but considerable enlargement and refinement of the program, 

 so as to subject these preliminary findings to exceedingly careful and dependable 

 verification and extension. 



The Smithsonian Institution has been for at least half a century the agent 

 which has specialized most successfully on solar radiation problems. No other 

 institution is in as good a position as is it to continue to lead in this field. The 



' Smithsonian Misc. Coll., vol. 95, no. 12, May 1936. 



Smithsonian Miscellaneous Collections, Vol. 95, No. 15 



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