NO. 3 SOLAR RADIATION AND THE WEATHER CLAYTON ' 7 



The numbers in table III show the mean departures from normal 

 temperature in Buenos Aires for five days preceding and 33 days 

 following maximum of solar radiation. These maxima are arranged 

 according to intensity, differing by 0.020 calories, or about i per cent 

 of the mean solar radiation at the earth's distance outside the atmos- 

 phere, according to the determinations of Abbot. The results are 

 given in tenths of a degree Centigrade. 



The numbers in table IV show in like manner the mean tempera- 

 ture preceding and following minima of solar radiation. 



A plot of the means (1909-1918) in table III are shown in figure i 

 by curves A I to A^. 



A I shows the variation of temperature associated with the largest 

 values of solar radiation and indicates that these are followed by 

 temperature waves of a period of between 10 and 11 days. This 

 periodicity is clearly shown by the minima on the 4th, 14th, and 25th 

 days following the solar maxima. The waves following the solar 

 maxima of less intensity show shorter intervals between maxima and 

 minima. After values of 1.980 calories the mean distance between 

 the most marked maxima is about seven days. After solar values 

 of 1.960 calories the waves appear to be still shorter, but since, with 

 the exception of a, the maxima and minima appeared to be near the 

 same days as those following 1.980, an average of the two was taken 

 and is plotted as A 4. This curve shows very clearly periodic waves 

 of between six and seven days. 



Curves A6 and A/ show the variations associated with the larger 

 solar values (over 1.990 calories) separately for sun-spot maximum 

 (1915-1918), and for sun-spot minimum (1909-1914). The maxima 

 and minima of the curves appear to occur somewhat earHer at the 

 time of sun-spot minimum and to have a lesser range. 



This result is perhaps because of difficulties in the measurement 

 of the radiation values, more values of really smaller intensities being 

 included in the minimum years. 



The values from table IV are not plotted, but in general they show 

 waves of opposite phase to those in table III, the longest waves 

 following the extremely low values of solar radiation. 



Taking the mean solar radiation as i .94 calories and supposing the 

 waves following maxima of 2.00 calories and those following minima 

 of 1.88 calories to oscillate in opposite phase, then the difference 

 ought to give the character of the waves better than the separated 

 means. A plot of this dift"erence is shown in figure i, Ai, and it shows 



