Sedou drifted, generally moved quite calmly. The ship experienced sharp rotations only with 

 sharp wind changes, which were accompanied also by sharp changes in the direction of the drift. 

 Fissures, breaking up, and heaping of ice occurred simultaneously. 



Thus, on 12 November 1938, it was observed on the Sedou that the ice began to move in an 

 unusual manner after the southeast wind, with a force of 7 to 8 points (which blew for a period of 

 48 hours), had been replaced by a powerful southwest wind. A fissure passed at 50 to 70 m from 

 the ship and widened up to 10 to 15 m. An open patch of water (polynya) 100 x 150 m square was 

 formed on the starboard side of the ship. 



Hummocks appeared simultaneously in all directions. The course of the ship changed quickly 

 from 100° to 75°, and later turned to 87°. 



Thus, rotation inevitably results from collision of ice fields and ice blocks which have some 

 freedom of movement relative to one another, such as when they are situated in sea currents which 

 differ in velocity and direction or become subject to wind which acts differently on various ice 

 blocks with regard to their size and form. The ice fields begin to collide and to rotate; as a result, 

 their sharp corners break off gradually and become worn. If viewed from the top, the ice blocks 

 have a characteristic, monotonous, oval form. Only ice blocks which have not been separated from 

 ice fields, and broken-up ice fields which cannot undergo any further break-up because of solid ice, 

 retain their initial angular contour. This process is particularly characteristic of warm ice; i.e. , 

 for spring and summer. 



LITERATURE: 38, 72, 77. 



Section 96. Break-up of Fast Ice 



As we have seen, the break-up of ice fields in the open sea occurs as a result of wind action, 

 sea currents, and ice fluctuations. The break-up of fast ice occurs as a result of the same factors. 

 Naturally, it is necessary to distinguish the break-up of fast ice at the shore, which is open to the 

 sea, and that of fast ice in closed bays and narrow straits. 



The break-up of fast ice in open shores, even with solid ice present in the sea, may occur 

 during the entire winter. Thus, e.g., at Cape Cheliuskin, in the winter of 1942-43, fast ice broke 

 up four times before the end of March: 5 and 24 November, 27 January, and 25 March. 



On 24 November, the center of an intense cyclone was situated between Franz Joseph Land 

 and Novaya Zemlya (pressure: in the Bay of Tikhara, 981.6 mb, on Cape Cheliuskin 1010.7 mb). 

 Over the entire Kara Sea, a southwest storm reached a force of eight marks or points. As a 

 result, the fast ice at Cape Cheliuskin was fractured. 



On 26 January, the center of a vigorous cyclone was situated toward the north of Franz Joseph 

 Land (pressure: in the Bay of Tikhara 980. 9 mb, on Cape Cheliuskin 1010.2 mb) . On 27 January, 

 the center of the same cyclone moved to the northern part of Severnaya Zemlya (pressure: on the 

 Island of Domasch 984.5 mb, on Cape Cheliuskin 1000.6 mb, and at Tiksi Bay 1035 mb). A stormy 

 southwest wind reached a force of 8 to 9 points. As a result, the fast ice at Cape Cheliuskin was 

 fractured. Furthermore, on 28 January, an unusual rise in the level to 1.25 above the normal was 

 noted at Cape Cheliuskin. This increase was evidently connected with observed storms. Some 

 small barges and mooring ropes were damaged at this time. 



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