In addition to the alternation of warm and cold waves, one must remember that each sub- 

 sequent cyclone in each series of cyclones passes somewhat to the south of the preceding cyclone 

 and that after the passage of the last cyclone of a given series a cold wave penetration occurs. 



During the first natural synoptic period in the Kara Sea, which lasted from 1 to 9 October 

 1943, several centers of cyclones moved subsequently from the Barents Sea approximately along 

 the longitude of Gugorskiy Shar; during the second period, from 10 to 17 October, the center of cy- 

 clone intersected the Kara Sea, moving in a southeasterly direction from Franz Joseph Land. Dxir- 

 ing the third period, from 18 to 24 October, the center of a cyclone intersected the southern portion 

 of the Kara Sea, moving in a southeasterly direction. During the fourth period, from 24 to 31 

 October, no center of any cyclone was observed in the Kara Sea. 



As a result of such development of synoptic processes, winds blowing from the southwesterly 

 quadrant were not observed on Ostrov Uyedineniya after October, 1943. After 19 October, easterly 

 winds became established and air temperatures began to decrease rapidly. On 24 October, the 

 first ice appeared and as early as 27 October the air temperature dropped to -14°. 



Thus, the cooling of the sea always occurs by leaps. Each of the leaps is characterized by 

 the duration and intensity of a cold wedge of air. In consequence, at a certain time the temperature 

 of the upper water layers drops to the freezing point. The continuation of a given cold wave or the 

 arrival of a new one, even if insignificant, appears to be sufficient for the beginning of ice 

 formation. 



The cooling of the sea surface to the freezing point is, however, determined not only by syn- 

 optic but also by oceanological conditions. Indeed, the rate of cooling of the sea is measured by the 

 amount of calories given off to the atmosphere by a unit surface of the sea in a unit time. But this 

 number of calories is not at all proportional to the decrease of temperature of the sea surface. As 

 we shall see below, the amount of heat given by the sea to the atmosphere, at the same air temper- 

 ature and Initial temperature of sea surface, in order to lower the temperature of the latter to the 

 freezing point can be extremely variable, even for areas lying very near each other. As a rule, the 

 smaller the depth, the more abrupt is the lowering of the surface temperature. 



If the surface layer is very thin and its salinity so low that, even when cooled to the freezing 

 temperature, the density of the surface layer remains lower than the density of the underlying 

 layers, radiation alone may suffice for the cooling of the surface layer to the freezing point and for 

 subsequent ice formation, despite the high temperature of the subsurface water layers and high 

 temperature of the air. 



Thus, if the surface layer is thin and the water is sufficiently stratified, its cooling to the 

 freezing temperature occurs at the greatest possible speed when the frost is severe, the sky is 

 clear (intense reradiation) and the wind is absent. 



The wind brings about a rapid drop in temperature of the surface layer to the freezing point 

 only If its force is insufficient to Intermix the surface layer with the warmer, lower layers. Other- 

 wise, not only can the temperature of surface layer rise, but the ice that has been formed can be 

 destroyed. With wind and low air temperatures, on the other hand, the cooling involves at once a 

 large water mass; as soon as the freezing temperature is reached, ice formation begins at once in 

 the entire layer that has been cooled. 



LITERATURE: 62, 73, 77. 



50 



