OPEN 

 WATER 



pUMMOCKED O ROTATION 

 ICE OF THE ICE 



COMPRESSION 

 =f STRONG _ 



"■"weak 



SCATTERING 



Figure 139. Diagram of the position of regions of hummocking, polynyas 

 and rotation of the ice during the passage of a cyclone over a 

 rectangular channel. 



Novaya Zemlya lead will result. If tlie patlis of the cyclone centers pass approximately along the 

 parallel of Yugorskii Shar, the Yamal lead will form, etc. 



In such calculations, one must remember that the ice edges will not move toward the shore 

 or the shore ice at the same rate of speed, given the same wind force, because of compaction and 

 hummocking. For example, considerably less time is required to bring ice from a concentration 

 of 5/10 to 6/10 than is required to bring it from a concentration of 8/10 to 9/10. Of course, the 

 same thing applies to hummocking. It seems reasonable to assume that these phenomena follow 

 the logarithmic law, but thus far we have no supporting observations. 



LITERATURE: 77. 



Section 139. The Drift of on Isolated Ice Floe 



As direct observations have shown, individual icebergs, floes, and small ice fields may drift 

 at a speed as great as 1. 5 knots or 80 cm/ sec and more during fresh winds, i. e. , the wind drift 

 speed of isolated floes and fields may be 2 to 3 times greater than the velocity of the wind-driven 

 current which forms simultaneously. * 



In 1935 to 1937, Shestiperov, observing the wind drift of ice floes in the Chuckchee Sea by 

 means of a theodolite set up on Cape Schmidt (Mys Schmidt) at an elevation of 48 m above sea level, 

 noted that the mean wind factor during winds which blew along the coast (in either direction) varied 



*On an ice-free sea the energy of the wind acting on the surface of the sea is expended on the 

 formation of waves, on mixing, the formation of currents and the heating of the sea. Where there 

 is an ice cover, the wind energy is not expended on the formation of waves, and thus there is less 

 mixing. However, the uneven surface of the ice offers high resistance to the wind, which explains 

 the relatively rapid drift of the ice. 



381 



