NON-PERIODIC CHANGES. 



75 



If, however, we had used the average minimum temperature instead of the mean tempera- 

 ture for the comparison, the years would have been arranged thus : — 



Table 34. 



in which only one month of the lour is out of the sequence. 



The investigation has been carried further by plotting the reduced range for the cold 

 months against the average maximum and average minimum temperature of the month. The 

 points for the months May to August are plotted in figure 27. A glance shows at once that 

 whereas there is only a small tendency for the points to lie on a straight line in the upper 



-40 



-55 



-30 



-25 



-20 



-15 



Fig. 27. Reduced temperature ratiRe plotted against maximum and minimum temperatures, 



diagram, there is a considerable tendency in the lower diagram. This means that during the 

 period May to August the reduced range, i.e., the unperiodic temperature changes, depends 

 much more on the minimum than on the maximum temperatures. The relationship, expressed 

 in statistical terms, is represented by the correlation coefficients — 7 and —-2 respectively. 



