NO. 9 FORECAST OF U. S. PRECIPITATION — ABBOT 21 



Times. — The growth of population, destruction of forests, multi- 

 plying of oil engines, automobiles, and airplanes alter the properties 

 of the atmosphere and thereby shift phases of periods. Hence, as 

 stated above, I divide the thousand months of records into first and 

 second halves and compute the phases and amplitudes within the two 

 parts separately. 



Table 7a. — The sixfold groupings.* The 9-1/10-month period. Eastport, Me. 



Values in percentages of normal precipitation 



A. Wolf sunspot numbers below 20 



01^4 610k ci^4 as ok b-2^3 cz ok 2 2 ~ 6 A 



Mean 98 

 B. Wolf sunspot numbers exceed 20 



ai ok 61^3 civj-i 020k 620k C2fa 2 2 -J- 6 



87 92 92 84 97 89 54 1 90 



Mean 100 



* The shifting of phases is indicated by arrows as in figure 9 and table 7. The accompany- 

 ing subscripts indicate the number of months shifted up or down. 



Not only so, but considerable differences of amplitude between the 

 two halves are sometimes found. As forecasts are for present and 

 future time, weights, as 2/1, 3/1, or 4/1, are given to favor the second 

 half when considerable differences in amplitude of periods between 

 the two halves appear. It matters not whether the later amplitudes 

 are the less or the greater, the larger weight is ascribed to amplitudes 



