NO. 8 



HARMONIC PERIODS IN PRECIPITATION — ^ABBOT 



I give in figure 4 only the periods in Category 2. These, about 

 60 percent of the whole record, relate to intervals when Wolf sunspot 

 numbers exceed 20. The other 40 percent (in Category 1) were also 

 computed and used in the forecast below. But as their forms and 

 amplitudes are similar to those of Category 2, I omit printing them 



Fig. 4. — Rochester harmonic periods, 1884-1956. 

 Ordinates percent normal precipitation. 



here. I give in table 2 details of interest regarding the periods plotted 

 in figure 4. 



In Section 3 of figure 4 (18^ to 68| months) all periods had over- 

 riding subperiods, such as ^, ^, \. These were removed and not shown. 

 Figure 3 illustrates by numbers and forms the method of clearing 



I 



