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THE DEPENDENCE OF TERRESTRIAL TEMPERATURES 

 ON THE VARIATIONS OF THE SUN'S RADIATION 



By C. G. abbot 



Secretary, Smithsonian Institution 



The burden of this paper is an affirmative answer to two ques- 

 tions: I. Does the variation of the sun's radiation sensibly afifect 

 the course of temperature in terrestrial weather? 2. Conversely, does 

 the march of terrestrial temperature support the view that the sun 

 is a variable star? 



As long ago as 1920 Clayton expressed his affirmative conclusions 

 as to these questions in a paper ^ published by the Smithsonian Insti- 

 tution. I introduced Clayton's paper of 1920 with a note, from which 

 I shall quote at the end of this discussion several paragraphs still 

 pertinent, including the text figure which accompanied my note as the 

 frontispiece of Clayton's paper. I returned to the same subject in 

 1931 in my paper ^ "Weather Dominated by Solar Changes", in 

 which I employed solar observations made at Montezuma, Chile, 1924 

 to 1930, in relation to the temperature departures at Washington and 

 other stations. I am now able to present the results of 5 more years 

 of solar study, with a revision of the work published in my paper of 



1931- 



By a more discriminating scrutiny of the solar data I have elimi- 

 nated some doubtful cases of solar change in the period 1924 to 1930, 

 formerly included. Unfortunately, the solar radiation cannot yet be 

 determined from a single day of observation with an accuracy better 

 than about 0.3 percent. Hence, it is only by a well-supported series 

 of quite a number of successive days' values of high apparent relia- 

 bility, trending steadily in a given direction, that we may be well 

 assured that a real and not an accidental indication of solar change 

 is before us. 



In volume V of the Annals of the Astrophysical Observator}', table 

 31 gives a long series of Montezuma measurements of the " solar 



' Smithsonian Misc. Coll., vol. 71, no. 3, 1920. 

 * Smithsonian Alisc. Coll., vol. 85, no. i, 1931. 



Smithsonian Miscellaneous Collections, Vol. 95, No. 12 



