NO. 3 SOLAR RADIATION AND THE WEATHER CLAYTON AQ 



table XVII show that the change ranges from about 0.2 C. to about 

 0.8° C. in the tropics ; while in the temperate zones, where the tem- 

 perature variations are more controlled by wind variation than by 

 direct solar radiation, the ratio of change exceeds 1.0° C. and at some 

 stations 2.0° C. 



9. The results of these researches have led me to believe (i) that 

 if there were no variation in solar radiation the atmospheric motions 

 would establish a stable system with exchanges of air between equator 

 and pole and between ocean and land in which the only variations 

 would be daily and annual changes set in operation by the relative 

 motions of the earth and sun; (2) the existing abnormal changes 

 which we call weather have their origin chiefly, if not entirely, in the 

 variation of solar radiation. 



APPENDIX 



REPORT ON THE USE OF SOLAR RADIATION VALUES IN 

 FORECASTING THE WEATHER OF ARGENTINA 



Prof. G. O. Wiggin, Director of the Argentine Weather Service. 



Dear Sir, In compliance with your request I herewith submit a report on 

 the effort made in the forecast department to use the observation of variations 

 in solar radiation in improving the weather forecasts of this service. 



These measurements after being freed from atmospheric influences show 

 that the heat emitted by the sun is variable, and when the publications of the 

 Smithsonian Institution reached this office a study was made of a possible 

 connection between these solar variations and variations in the weather of 

 Argentina and of other parts of the world. This study was published in the 

 Boletin Mensual of June, 1916, and in Publication 2446 of the Smithsonian 

 Institution. 



This study and others not yet published indicated a relation between solar 

 changes and the weather in different parts of the world and suggested the 

 usefulness of such solar measurements as an aid in weather forecasting. 



In July 1918 a station for solar measurements was established in Chile by the 

 Smithsonian Institution and application was made to the Director of the Astro- 

 physical Observatory for the use of these values by the Oficina Meteorologica 

 Argentina. This being granted, the observations were at first transmitted by 

 mail and later by cable. 



This was made possible by the kindness of the Central and South American 

 Telegraph Co., through the local manager, Mr. Hussey, and by the enthusi- 

 astic co-operation of Mr. A. F. Moore of the Solar Observatory and his 

 assistant, Mr. L. H. Abbot, who undertook the arduous work of reducing the 

 observations day by day. This task they have accomplished without a break 

 when observations were possible. The first telegraphic transmission was 

 received on December 23, 1918. 



The use of the data for forecasting began, however, early in December from 

 the reports by mail, and has been continued since in so far as the data permit. 



