6 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I39 



my former papers, 1 with slight changes dictated by later experience. 



Periods in sun and weather. — The sun's radiation which we see 

 and feel, like that of many other stars, is variable. Solar output of 

 radiation seldom exceeds 2 percent in its variation. However, its 

 variation comprises as many as 60 regular periodic pulses, ranging 

 from 1 month or less to 273 months or more. All are exact submul- 

 tiples (or aliquot parts) of 273 months, as 91, 39, 7 months, and many 

 more. They range in amplitude from 1/50 to 1/4 percent. All go 

 on simultaneously, like overtones of a musical note. 



As many as 30 of these exact periods have been found in monthly 

 weather records which have been kept from 1870 and earlier. They 

 occur in records both of precipitation and temperature. Far from 

 being confined to fractions of 1 percent, as in solar radiation, in pre- 

 cipitation they individually range from 5 to 35 percent of the normal 

 average. In temperature they range from i° to 3 F., and these limits 

 refer to 3-month smoothed records. Owing to the large number of 

 these weather periods, some in plus, some in minus phases at any one 

 time, their combined influence is not usually startlingly great. 



Normals. — Long records of weather ordinarily state "normal" 

 monthly values found by taking the monthly averages of all the years 

 tabulated. I have found considerable differences in normals if com- 

 puted separately for years of high and low sunspot frequencies, re- 

 spectively. I therefore compute separate monthly normals for years 

 above and below an average of 20 Wolf numbers in sunspot fre- 

 quency. From these normals I tabulate the departures in tempera- 

 ture, and the percentages of normal precipitation. 



The monthly values have too wide jumps to be most useful. I 

 smooth the record by 3-month consecutive means. Thus for February 

 I use ( January + February + March) X 1/3, and similarly for other 

 months. 



Lags. — Supposing, contrary to meteorologists' opinion, that the 

 variation of the sun is the real cause of the variation of the weather, 

 since it has identically the same periods, I point out that well-known 

 variations of insolation suffer variable lags in their weather influence, 

 depending on place and time. 



Lags of solar effects, as they differ with locality, indicate that the 

 state of the atmosphere is an important factor. The atmospheric 



x a, Journal of Solar Energy, Sci. and Eng., vol. 1, No. 1, January 1957; 

 b, ibid., vol. 2, No. 1, January 1958 ; c, Smithsonian Misc. Coll., vol. 123, No. 4, 

 August 1953; d, ibid., vol. 128, No. 3, April 1955; e, ibid., vol. 128, No. 4, 

 June 1955; f, ibid., vol. 134, No. I, September 1956; g, ibid., vol. 138, No. 3, 

 February 1959. 



