EFFECT OF SHORT PERIOD VARIATIONS OF SOLAR 



RADIATION ON THE EARTH'S ATMOSPHERE.' 



Bv H. HELM CLAYTON 



With 8 Ch,arts 



INTRODUCTION 



Several years ago the Director of the Astrophysical Observatory of 

 the Smithsonian Institution announced the discovery of variations in 

 the intensity of solar radiation with intervals of only a few days 

 between the maxima and the minima of intensity. 



It is a matter of interest and importance to determine whether 

 these variations are coincident with atmospheric changes on the 

 earth. Recently there was received from Dr. Abbot a pamphlet *' On 

 the Distribution of Radiation over the Sun's Disk and New Evidences 

 of the Solar Variability " by C. G. Abbot, F. E. Fowle, and L. B. 

 Aldrich (Smithsonian Misc. Coll.. Vol. 66, No. 5). This pamphlet 

 contained measurements made with the bolometer at Mt. Wilson. 

 California, during the years 1913 and 1914 for the purpose of 

 measuring the variability of the solar radiation. The results were 

 determined in calories of heat per minute corrected to represent 

 values outside the atmosphere. 



In making a comparison between solar and atmospheric changes 

 it was decided to use the method of correlation as worked out by Karl 

 Pearson (see " Theory of Statistics " G. Undy Yule, London, 1912). 



This method is the one used by the most modern investigators for 

 comparing variables with each other, and is free from the error of 

 personal bias which may enter when the investigator confines himself 

 to curves and arithmetical averages. 



The great varieties of local climate in the world caused by the dis- 

 tribution of land and water, mountain and valley, pole and equator, 

 make it evident that any solar change may have very different effects 

 in different parts of the world, and, hence, it seemed desirable for 

 a first trial to select, out of the multitude of meteorological stations, 



^ Published simultaneous]}' in English and Spanish with the consent of the 

 Director of the Oficina Aleteorologica Argentina. 



Smithsonian Miscellaneous Collections, Vol. 68, No. 3 



