NO. 3 SOLAR RADIATION AND THE WEATHER CLAYTON I3 



(2.000 calories). Curve T is plotted from the same values as A6 in 

 figure I, but is displaced three days to the left and inverted. That is, 

 day 3 is plotted under day o of the solar curve and plus values are 

 plotted below the mean line and negative above. The values for 

 sun-spot minimum from which Ay was plotted in figure i were 

 treated in the same way and plotted in T2 under S6. The similarity 

 of S5 and Ti are very striking and, I think, can leave no doubt but 

 that maxima of solar radiation are followed about three days later 

 by minimum temperatures at Buenos Aires. 



The correlation between the mean radiation values for the 30 days 

 following the radiation maxima of 2.000 and the mean temperatures 

 at Buenos Aires three days later is —0.66, and for a change of i per 

 cent of solar radiation the temperature change is 1.4° C. At sun-spot 

 minimum the correlation is less, being —0.48 for 24 days, and the 

 temperature change is 0.5° C. Both these values were computed by 

 the formula: 



y= s^- (3) 



The closeness of the relation at the time of sun-spot maxima may 

 be realized further by the statement that the three highest means of 

 solar radiation; namely, the means exceeding 1.958 calories (see 

 table V sun-spot maxima), were followed three to four days later 

 by the three chief minima of temperature; namely, the mean depar- 

 tures below —1.2° (see table IV sun-spot maximum), the departures 

 being given in tenths of a degree Centigrade. Seven maxima between 

 1.948 and 1.958 were followed three days later by minima of tem- 

 perature differing less than 1.1° from the mean, except in one case 

 where the minima is obscure. The two lowest values of solar radia- 

 tion; namely, the means below 1.935, were followed three days later 

 by maxima of temperature, in one case by the highest mean depar- 

 ture from normal temperature; namely, 1.7°, and in the second by a 

 mean departure of 1.0°. 



Annual Inversion in the Correlations Between Solar Radia- 

 tion AND the Temperature in Buenos Aires 



It must be borne in mind, however, that these observations on the 

 sun were all taken in the winter half-year of the southern hemisphere. 

 The recent observations taken in Chile during the summer half-year 

 show that the correlation in summer is not inverted but is direct. 

 Observations were begun in Chile in late July, 191-8, and correlation 



