REPORT OF THE SECRETARY 107 



The variations observed in the solar constant by the Astrophysical Observa- 

 tory of the Smithsonian Institute during the last 30 years are mainly due to the 

 defects in the methods of determining the solar constant. If this conclusion 

 is accepted the subsequent work based on the supposed variability of the solar 

 constant is not valid. 



Dr. Paranjpe's paper was read at a meeting of the Royal Meteoro- 

 logical Society and favorably received and commented upon by 

 several of the principal meteorologists of Great Britain. 



Dr. Abbot's reply (Quart. Journ. Roy. Met. Soc, April 1939) 

 is abstracted as follows: 



The author cites five recent papers containing many evidences of solar 

 change ignored by critics. Chief among them, and in the author's opinion 

 unanswerable, are evidences that day to day solar changes profoundly influence 

 temperatures. Between 1924 and 1935 were found 320 dates, the beginnings 

 of sequences of observed rise or of fall of solar radiation. The average march of 

 departures from normal temperatures in four widely separated cities shows 

 opposite trends for 16 days following, respectively, these sequences of rising 

 and falling solar radiation. The separation of temperatures thus produced 

 reaches from 10° to 25° F. Similar curves of temperature departure are found, 

 on the average, in the years 1924 to 1930, to those found in the years 1931 to 

 1935. Selecting 46 cases of especially large solar changes observed, the 

 temperature effects which followed were in the same phase but about twice as 

 large as usual. A crucial test is given wherein correlation coefficients are 

 computed for the march of temperatures for 16 days after and for 16 days 

 before observed solar changes, as between rising and falling sequences of solar 

 variation. The correlation values are respectively: After, — 54.3±4.9 percent; 

 before, +11.1±6.0 percent. The first is 11 times its probable error and 

 therefore significant, the second less than twice its probable error and hence 

 meaningless. 



From these studies it appears that day-to-day changes averaging 0.7 

 percent in solar radiation are presumably real and competent to produce 

 major changes of 10° to 25° F. in temperature in the temperate zone. Such 

 changes may be conventionally represented by the repetition 18 times per year 

 of the day-to-day sequence, 3, 6, 9, 12, 14, 12, 9, 6, 3 thousandths calorie in 

 solar radiation. 



The author demonstrates that correlation of day-to-day solar constant values 

 from different obserA'atories, as relied on by critics, is incompetent to refute 

 the sun's important variability. For the author computes correlation 

 coefficients for 110 days as between the best stations, Montezuma and St. 

 Katherine, obtaining 6±6 percent. He then loads the values of each station 

 simultaneously with five humps of sequences such as just numerically specified. 

 The two stations are then certainly correlated, and carry assumed solar changes 

 adequate to produce from 10° to 25° F. in temperature departures. The cor- 

 relation coefficient now becomes 1S±6 percent, an increase of 12 percent, far 

 below what critics reqtiire as being evidential. 



The author points out that multiplication of values, as in monthly means 

 or in large groupings governed by magnitudes, may sufficiently reduce accidental 

 errors to give trustworthy evidences of solar variation, and cites numerous 

 cases of this sort not referred to by critics. 



