THE SUN'S SHORT REGULAR VARIATION AND ITS 

 LARGE EFFECT ON TERRESTRIAL TEMPERATURES 



By C. G. abbot 

 Research Associate, Smithsonian Institution 



I propose to show that there is a regular period of 6.6456 days 

 in solar variation, and that terrestrial temperatures respond with 

 changes ranging from 2° to 20° F. in exactly the same average 

 period of recurrence. While the sun's variation appears to be per- 

 fectly regular in phase, always recurring on the day predicted, the 

 terrestrial responses come sometimes for a month or more in succes- 

 sion from I to 3 days early or late. This, which by mechanical analogy 

 we might call backlash, is doubtless the circumstance which hitherto 

 has prevented meteorologists from recognizing the nature of this large 

 temperature variation. When examined with the knowledge of the 

 6.6456-day solar period, the temperature effect is indeed so strikingly 

 obvious, as the reader may see from figures 3 and 5, that no one could 

 doubt that it is both real and a major element in weather. Meteoro- 

 logically, this regular average periodicity appears to be a new dis- 

 covery. It is not to be confused with temporary weather periods, 

 ranging from 3 to 7 days in length and changing their phases from 

 time to time, which have been discussed by Clayton, Arctowski, and 

 others. 



When I retired from administrative duties, in July 1944, I proposed 

 to devote myself to the study of the records of solar variation obtained 

 by the Smithsonian Astrophysical Observatory. I hoped to publish 

 such detailed and thoroughgoing discussions of these observations, and 

 of their bearing on meteorology, as might convince scientific men of 

 the veridity of some conclusions already published. I hope the present 

 paper will be followed by others in this field. 



1. PREVIOUS STUDIES 



In 1936 I published two papers on the dependence of terrestrial 

 temperatures on solar variation.^ It was shown that sequences of rise 



1 Smithsonian Misc. Coll., vol. 95, No. 12, 1936, and vol. 95, No. 15, 1936. 



SMITHSONIAN MISCELLANEOUS COLLECTIONS, VOL. 107, NO. 4 



