546 



HIRKF.I.AND. TIIK NOKWKGIAN AURORA I'OLARIS EXPEDITION, igO2 1903. 



SEPARATION OF GREAT AND SMALL DISTURBANCES. 



105. The separation of perturbations into great and small storms has been performed according to 

 rules given in the introduction to this chapter, and for the period of three months common to the four stations. 



In table C is given the storminess for great and small storms for each five-day period. 



The quantity S S T will be taken as representing the storminess of small storms. 



The storminess of small storms only shows small and quite irregular variations from one Five-day 

 period to another, showing that the cause of small storms is almost constant!}' present. In view of our theory 

 this would mean thai almost at any time pencils of electric rays from the sun (ire striking the earth, 

 and we have to suppose a great number of sources of electric radiation spread over the surface of the 

 sun. On the ground of this fairly constant supply of disturbance, the great storms, from the principal 

 sources of the sun, are superposed. 



TABLE CII. 



The ratio of the storminess of great storms to that of the small ones, given in table CII, is seen tu 



vary between 2.05 for Kaafjord and 4.39 for Axel&en, or, in other words, most of the storminess is due to storms 



_5 

 belonging to the group of great storms. The ratio "-' T is considerably greater for the group of large 



->! 



storms than in the case when all storms are counted. 



The distribution over the day of large and small storms is given in table CI, and graphically 

 represented in fig. 199. Comparing these curves with those in fig. 196 we notice tinat the characteristic 

 diurnal period found from the treatment of all storms is even more marked for the group of large stiirmt. 

 We further notice that the greater part of the calm period of the day is due to small disturbances, 

 Table CIII gives the conditions for the period of four hours during which the large storms have the 

 smallest storminess. We notice that the quantity I is greatly increased in the case in which the small storm- 

 are left out. 



TABLE CIII. 



is the total storminess of great storms for the calm period 



\<Jc/s - 



- small 



