NO. 6 



SOLAR RADIATION AND WEATHER CLAYTON 



53 



The Greenwich Observatory pubhshes a table giving the amount 

 of faculse visible on the sun each day. From these tables the dates 

 of each successive maximum of faculae were taken from July, 1918, 

 to December, 1921, and tabulated with solar radiation on the day on 

 which the maximum of faculse occurred, and for two days before 

 and two days after. The number of cases was over 200. The mean 

 solar radiation for each day is given in table 16. 



Table 16. — Mean Solar Radiation with Maxima of Faculcs, 1918-1921. 



Mean Year i . 9477 



Mean Apr.- Sept i . 9455 



Solar Radiation and Faculae 

 1918-1921 

 Days Day Days 

 before obs. after 



•■ • Year 



X— — — X Sept. -Apr. 



Fig. 40. 



The means are plotted in figure 40. The continuous curve shows 

 the means for the whole period, while the broken curve shows the 

 means for the period April-September, when observing conditions 

 are best. The curves show a marked maximum of solar radiation on 

 the day of the maximum of faculae. The increased radiation shown 

 by the observations of April to September amounts to about one- 

 third of I per cent. 



