INVESTIGATIONS ON PERIODICITY IN THE WEATHER 

 By H. Helm Clayton. 



Presented March 8, 1899. Received April 19, 1899. 



Investigations on periodicity in the weather have occupied the at- 

 tention of many workers, and I can refer only in a brief way to inves- 

 tigations along other lines than those on which I have been engaged. 



A knowledge of the existence of annual and diurnal periods in the 

 weather is older than history, and the fact that these periods depend on 

 changes in the position of the sun is universally recognized. A larf^e 

 part of the labor of meteorologists at the present time is devoted to 

 determining, for different parts of the world, the amount of change in 

 weather conditions resulting from these periods. 



Many investigators have sought to prove a period in terrestrial mag- 

 netism and in meteorological phenomena coinciding with the rotation of 

 the sun on its axis. Among these are Broun (Comtes Rendus, 1873), 

 Hornstein (Sitzungsberichte Wien-Ak., 1873), Liznar (Sitzungsberichte 

 Wien-Ak., 1885, '86, '87, and '88), Balfour Stewart (Nature, 1879 and 

 1884), Nerwander, (Poggendorffs Annalen, Bd. LVIH.), Buys Ballot 

 (Archives Neerlandaises, Tom. XX.), Muller (Melanges physiijues et 

 chemiques, Bnll. Ac. St. Pet., 188G), Schmidt (Sitzungsberichte Wien- 

 Ak., 1888), Veeder (Proc. Rochester Acad. Sci., 1889), Hall (Araer. 

 Jour, of Sci., Vol. XLV., 1893), and Bigelow (Amer. Meteor. Jour., 

 1893). The results of these researches differ from one another, and 

 none has received general acceptance. 



Also there has been much study of the relation between the frequency 

 of sun spots and corresponding periods in the weather. The results are 

 conflicting, and the relation is not accepted as proved. The relation if it 

 exists is undoubtedly complex, but this is what might be expected in 

 meteorological phenomena. An excess of rainfall in India implies an 

 increased ascent of air. This demands an increased descent of air in 

 some other part of the world, as for example in Russia. Hence, an 

 excess of rainfall in India would be coincident with a deficiency in Russia, 

 and the two would have opposite phases in regard to the sunspot period, 



