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SHORT PERIODIC SOLAR VARIATIONS AND 



THE TEMPERATURES OF WASHINGTON 



AND NEW YORK 



By C. G. abbot 

 Research Associate, Smithsonian Institution 



In my paper read before the National Academy of Sciences in 

 April 1949, fairly successful predictions of 55 minima of Washington 

 temperatures for the year 1948 were discussed. The 55 dates in 

 question were the dates when the period of 6.6456 days ^ would recur 

 in the same phase as on January 17.0000, 1946. It was privately indi- 

 cated to me, after the delivery of my paper, that certain correlation 

 studies which had been made on New York City temperature de- 

 partures raised doubts if similar results would have been obtained for 

 that station. By the kindness of E. J. Christie, Meteorologist in 

 Charge at New York, Weather Bureau forms 1030 giving departures 

 from normal temperature for every day from January 1928 to date 

 were furnished for me to study this question. 



WHY EXPECT SUCH A REACTION? 



Before proceeding further, let us refresh our minds on the reasons 

 for supposing that there should be a period of 6.6456 ^ days in 

 meteorology.- Solar radiation is the source which maintains the 

 earth's temperature and other meteorological phenomena. If the solar 

 radiation is variable, these must be expected to vary. Daily observa- 

 tions by Smithsonian observers carried on at Montezuma, a mountain 

 9,000 feet high in the Atacama Desert of northern Chile, show that 

 small fluctuations of the sun's output of radiation do occur. A 

 statistical study of them showed that there is an approximately regu- 

 lar solar variation of about 6f days' period. 



The departures from normal temperatures at Washington between 

 the years 1910 and 1945 were tabulated in 6f-day intervals for the 

 months of May and November, separately. On plotting the 6f-day 



^ As shown below a small correction now alters this period to 6.6485 days. 

 - See Smithsonian Misc. Coll., vol. 107, No. 4, Apr. 4, 1947. 



SMITHSONIAN MISCELLANEOUS COLLECTIONS, VOL. Ill, NO. 13 



