l^otifffem^ ifund and Koebling JFund 



WEATHER DOAIIXATED BY SOLAR CILVNGES 

 Bv C. G. ABBOT 



My title suggests a radical change of view regarding weather and 

 weather forecasting. Let us contrast, for a moment, weather and 

 climate. All men realize that it is the sun which furnishes the heat 

 which warms the earth, and that the regular motions of rotation of 

 the earth upon its axis, and of its revolution in its orhit around the 

 sun produce those periodic variations of the solar heating which 

 govern climates. Differences in latitude and of proximity to oceans 

 and to other great terrestrial features introduce alterations from place 

 to place in these periodic changes of solar heating; thereby are pro- 

 duced climatic differences. As regards weather, which consists in 

 departures from regularity in climate, I suppose that practically all 

 meteorologists have been holding- hitherto that it depends principally 

 on the complexities of the earth. According to that view, weather 

 represents, as it were, the changing eddies and whirlpools in the 

 Niagara of climate, due to the jutting rocks of local circumstances, 

 and, owing- to enormous complexities, is essentially impredictable for 

 any considerable time in advance. 



I shall present evidence to show that weather, on the contrary, is 

 caused chiefly by the frequent interventions of actual changes of the 

 emission of radiation within the sun itself. Local conditions, to be 

 sure, alter the magnitudes and times of the effects of these interven- 

 tions into terrestrial aft'airs by the variable sun. but in ways determin- 

 able by statistical studies. Hopeful indications will be given that 

 changes of the solar radiation and their weather-consequences may be 

 l-redictable long in advance. 



Figure i shows the dail}- observations of the solar constant of radia- 

 tion made at jMontezuma, Chile, by the Astrophysical Observatory of 

 the Smithsonian Institution since 1924. The values give the intensity 

 of the sun's radiation as it would be found l)y an observer in free 

 space situated at the earth's mean distance from the sun. As far as 

 possible, they are independent of any effects of the varying trans- 



Smithsonian Miscellaneous Collections, Vol. 85, No, 1 



