502 E. HUNTINGTON SOLAR HYPOTHESIS OF CLIMATIC CHANGES 



and its storminess was 99.8 per cent. Evidently here, just as in the 

 other case, when sun-spots were more abundant, storms were also more 

 abundant. 



There is still another method by which we may compare the number 

 of storms with the sun-spot numbers. Let us divide the 30 years for 

 which full records are available into six groups of five years each, accord- 

 ing to the sun-spot numbers. The first group will be the years having 

 the smallest sun-spot numbers, the next the five years having the next 

 smallest sun-spot numbers, and the last the five years of most abundant 

 spottedness. In the following table the first column shows the average 

 sun-spot number for each group, and the second column the average 

 storminess in percentages of the mean for 30 years. The third column 

 will be described later : 



Table 4 



Average sun-spot Percentage of Percentage of stormi- 



number for storminess in ness in main storm 



• five years North area of North 



America America 



4.5 95.5 74.7 



9.7 104.5 101.6 



24.5 101.6 99.4 



42.2 102.4 105.2 



58.0 90.4 (102.2) 98.2 (101.0) 



73.0 : 111.3 121.6 



This table should be compared with that for tropical hurricanes on 

 page 494. The storminess does not here increase with the regularity seen 

 among hurricanes, although perhaps it would do so if the whole northern 

 hemisphere were included. The chief irregularity is due to the group of 

 five years having an average sun-spot number of 58. These were the 

 years 1883, 1884, 1885, 1905, and 1906. The average storminess for 

 1905 and 1906 was 102.2 per cent, which is only slightly less than would 

 be expected if there is a regular increase in proportion to the sun-spot 

 numbers. The other three years, 1883 to 1885, were the first during 

 which the part of the United States west of 100° west was included in 

 the Weather Bureau's statistics of storms. It is probable that during 

 these early years the data are incomplete, and hence that our table is to 

 that extent inaccurate. If we omit this doubtful group, it appears that 

 when sun-spots are least numerous storms are least numerous. With a 

 moderate number of sun-spots, the storminess is close to the average, 

 while with extreme spottedness the storminess greatly increases. 



Kullmer's law of the shift of the storm track. — The apparent relation- 

 ship between the number of storms and the spottedness of the sun is 



