In the explanation of table 89 It was shown that the time necessary for the transformation by 

 melting of one ice percentage into another for any given ice thickness and any quantity of heat ab- 

 sorbed by the water could be obtained by multiplying the figures of the table by proper factors. 

 From this it follows that under any conditions, provided they are the same in both cases, nine- 

 tenths ice becomes eight-tenths ice in the same time interval as five-tenths ice melts away 

 completely. 



The aforementioned calculation once more confirms the importance of dispersion of ice for 

 melting and in particular explains the ability of individual large floes to last throughout the polar 

 summer. 



It must be noted that it is considerably more difficult to thin out close ice than ice already 

 opened and dispersed since the small and more movable ice formations are hindered in their move- 

 ment by the larger ice formations which have greater inertia and are less movable. Therefore, ice 

 floes of large area are not thinned out, but are as if broken into ice floes of smaller area but of 

 similar degree of compactness. That is why, while navigating in the ice, one often meets separate 

 strips and accumulations of close-ice alternating with more or less broad stretches of open water. 

 This phenomenon is strengthened by the fact that each separate ice floe which appears in the midst 

 of clear water in the summer time is extremely short-lived. Only large floebergs and icebergs 

 are capable of existing, separately for a long time and can float for great distances, especially if 

 their movement is connected with appropriate currents . 



Thus we may consider that in the melting period we will meet for the most part either eight- 

 to ten-tenths ice, or open water with scattered ice floes in the process of destruction, or in other 

 words, one- to two-tenths ice. Only in the case of tidal phenomena and under conditions of complete 

 lack of wind do we find ice of different compactness. 



In this respect, the disposition of ice in the Kara Sea at the start of navigation in 1940 was 

 extremely typical. In this case the pre-navigational air reconnaissance carried out in June estab- 

 lished the presence of a strip of open ice stretching approximately from Dickson Island to Severnaya 

 Zemlya. This strip subsequently became the basic region from which melting extended to the 

 northwest. At the start of navigation the whole band became free of ice and thereby made navigation 

 possible in the first navigational period. There is no doubt that this band of open-ice was formed 

 as a result of breaking-up of ice fields by suitable winds. 



Figure 112 shows the condition of ice in the southwestern part of the Kara Sea from 20 to 24 

 June 1943, according to observations of the icebreaker Mitioyan with additional data from simul- 

 taneous air reconnaissance. On the diagram there may clearly be seen the Novozemelski ice field 

 of the Kara Sea which is beginning to be destroyed, the Yamalskaya and Ob-Yeniseikaya polynya and 

 the strip of fast ice which still remains in the mouth of the Yeniseiski Gulf, reaching from Oleni 

 Island across Sibiryakova Island to Dickson Island. The same figure shows simultaneous observa- 

 tions of water temperature (denominator) and air temperature (numerator), made by the icebreaker 

 Mikoyan . These observations merit particular attention. Actually, in a comparatively small 

 stretch the water temperature varied within very wide limits — from 0.4° to 10.6°. During this 

 time a southeast air current prevailed over the region under observation and consequently a more 

 or less uniform air mass was drawn over the sea. Nevertheless, the air temperature over the sea 

 also varied, in a small expanse, within very wide limits — from 0.7° to 10.6°. Most remarkable 

 was the fact that despite the great differences in temperature of water and air in adjacent points of 

 the area, the difference between the temperatures of water and air at one and the same point in the 

 sea stayed within the limits of 2° with the exception of the region in direct proximity to Dickson 



322 



