510 E. HUNTINGTON — SOLAR HYPOTHESIS OF CLIMATIC CHANGES 



must be clearly iiiiderstood, however, that during recent times the process 

 has not gone far enough to produce belts which stand out unmistakably. 

 How far the process usually goes will be shown on a later page. 



In this connection Kullmer points out that Spoerer's law of the shift- 

 ing of sun-spots in latitude may also apply to cyclonic storms. At the 

 beginning of a new snn-spot cycle spots appear in about latitude 30° on 

 either side of the solar equator. As the sun^s activity increases, the loca- 

 tion of new spots is farther and farther toward the equator. When the 

 maximum intensity is reached, the average position is about 15° from the 

 equator. Then as a cycle dies away the zone of chief activity falls to a 

 latitude of 10° or less. Before this happens a new cycle begins in higher 

 latitudes, and for a period of about three years there are two distinct 

 belts, one waxing and the other waning. The double terrestrial belt at 

 times of maximum sun-spots may be of similar origin. The matter is 

 introduced here merely as a suggestion of one of the many interesting 

 lines of research which are opened up by the study of storms. 



Shifting of storms in the main storm belt. — In order to ascertain how 

 closely the shifting of the storm belt coincides with solar phenomena, I 

 have made an independent investigation of the area where there is the 

 greatest change in storm frequency from times of maximum to minimum 

 sun-spots. This area is inclosed within heavy meridians and parallels 

 on the map (figure 3). In a limited area of this sort the number of 

 storms depends almost wholly on the amount of shifting of the storm 

 belt and only slightly on the actual change in total storminess for the 

 whole country. As a first step, the 30 years for which accurate data are 

 available have been divided into six groups of five years each, in accord- 

 ance with the number of sun-spots, just as was done for the whole country 

 on an earlier page. The results are given in Table 4, on page 502. The 

 general conclusion is the same as for the continent; but the differences 

 between the groups are far more marked, because we are dealing with a 

 shift as ^ell as with actual differences in the total storminess. Making 

 allowances for the possible error in the group having a sun-spot number 

 of 58.0, where the figure for 1905 and 1906 is 101.0, instead of 98.2 for 

 the whole group, we see that in general the number of storms increases 

 with the spottedness. The middle groups are none of them far from 100 

 per cent. The difference between the highest and lowest groups, how- 

 ever, which for the whole continent amounts to 15.8 per cent, has here 

 increased to 46.9 per cent. The excess of 46.9 per cent over 15.8 per cent 

 represents the effect of the northward shifting of the main storm belt. 



If we divide our period of 30 years into four groups instead of six, the 

 relationships of sun-spots aud storms becomes much clearer than with 



