Il8 POLAR PROBLEMS 



the polynyas and leads, also occur as large-scale features associated 

 with definite regions, and it is therefore necessary to discuss them 

 briefly in their regional aspect. 



POLYNYAS AS A GENERAL PHENOMENON 



A few words first, however, with reference to the polynya as a 

 general phenomenon. 



The polynya occurs both in the pack ice and the Arctic Pack and 

 depends on the mutual motion of parts (field and floes) of the pack. 

 The motion of these parts depends on the winds, currents, tides, 

 resistance met with (islands, stamukhi, shoals, etc.) and on the vari- 

 ous dimensions and forms of the parts participating in the motion. 

 Owing to these factors this motion is very complicated in character. 

 Side by side with the progressive motion of the pack as a whole there 

 goes a rotary motion of its parts, as a result of collision, shock, and 

 pressure among them. Owing to this intricate motion, such a group- 

 ing of fields and floes may result as to form an area of open water or 

 an area with fragments of ice (glagons) in it. This area of open water 

 is called in Russian polynya. These polynyas are of a temporary 

 character, and, under the influence of the same combination of factors 

 that cause the motion of parts of the pack, they are closed in one place 

 and reopened again elsewhere, and so on. With a relatively large 

 number of polynyas and with channels connecting them, the pack has 

 the appearance of being more or less favorable for navigation, but it 

 is still tight enough to be called "close pack." 



REGIONAL POLYNYAS 



Now as to the polynya as a major regional feature. 



As such it has been observed in two localities (see Fig. i), off 

 eastern Siberia from north of the New Siberian Islands at intervals to 

 about Kolyuchin Bay and off Grant Land and northern Greenland. 



Great Siberian Polynya 



The former, which may be termed the Great Siberian Polynya, 

 is, according to all observations since 1820, permanent in character 

 and of great dimensions. Its observed positions, when plotted, shows 

 it clearly to be associated with the outer edge of the fully developed 

 fast-ice {heregovoi pripai) as defined in the present paper. The forma- 

 tion, existence, and extension of this Great Siberian Polynya depend 

 upon those physico-geographical conditions which produce the gen- 

 eral motion of the Arctic Pack, or, in other words, they depend in 

 this region on the northwest and west-northwest direction of the 

 drift, i. e. a direction obliquely away from the fast-ice. The width of 

 this polynya depends upon the fluctuations of the outskirts of the 



