24 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I07 



14. IS THE 6.64S6-DAY PERIOD USEFUL FOR WEATHER 

 FORECASTING? 



I now recur to the question whether the dates of shiftings of phase 

 and variations of ampHtude in the temperature curves, such as those 

 shown in figure 3, could be predicted. This is a very important in- 

 quiry. For, as just shown, the periodic variations of solar radiation 

 follow an exact time schedule, and doubtless can be computed in phase 

 for many years to come, as well as for many years preceding the year 

 1923, when our best observations of the solar constant began. Hence, 

 if we could know what allowances to make for phase shiftings, and 

 variations of amplitude, we could predict sun-caused variations of 

 temperature to be expected at Washington and other stations for 

 many years to come, and we could check this method of forecasting 

 against records of many former years. 



15. OBSERVED CHANGES OF PHASE AND AMPLITUDE IN 

 TEMPERATURE EFFECTS 



I have collected in table 6 the most certain of the data on phase 

 shiftings and variations of amplitude for Washington for all months 

 from the year 1910 to 1945, omitting those occasions for which the 

 curves like those shown in figure 3 were too indefinite to give trust- 

 worthy values. I give this table in the hope that meteorologists may 

 use it to discover the key to unlock this puzzle which, if found, would 

 enable them to profit by this proposed new method of moderate-range 

 forecasting. 



16. SEARCH FOR CAUSES OF CHANGES IN PHASE AND 

 AMPLITUDE IN TEMPERATURE EFFECTS OF THE 

 6.6456-DAY PERIOD 



I have spent a good many days on this problem myself. It was my 

 first impression that the variations of phase and amplitude were of 

 cosmic causation. I have found no correlation with the sunspot num- 

 bers, and only slight ones with the 8|-month, ii^-month, 21 -month 

 solar periodicities mentioned on page 181, volume 6 of the Annals 

 of the Smithsonian Astrophysical Observatory, which seemed possible 

 leads. Evidently some more sharply acting variable or variables must 

 govern such isolated, severalfold increases of amplitude as, for in- 

 stance, from January to February 1937, or from February to March 

 1943, in Washington. 



This consideration leads me to suggest the hypothesis that the 

 terrestrial temperature effects caused by the 6.6456-day solar period- 



