Nil as forms from lard ice on a calm sea. This is a dull opaque ice with a surface damp 

 from brine, grey, and easily discernible from the bridge of a ship or from an airplane. As opposed 

 to bottle ice, which is brittle, nilas is extremely plastic; it bends easily on a wave, and when 

 smashed, gathers into pieces. Burke arbitrarily divides nilas according to colors into dark and 

 light grey, limiting the thickness to approximately 10 cm. He further points out that the dark color 

 of nilas is due not so much to water shining through it as to its high brine content. Also, due to 

 this, the snow falling on the surface of nilas melts. 



With slight turbulence, ice formation sometimes seems to originate from many centers (disks 

 30 to 50 cm in diameter). This is the "pancake ice, " which is the most widespread initial form of 

 ice in the sea (figure 32). Pancake ice is often observed on lakes and quiet rivers. 



Figure 32. Pancake ice. 



Round forms of pancake ice are the most frequent. Toll's expedition observed the formation 

 of pancake ice in the form of ellipses during a 2 to 3 m/sec-wind. Such a change in form can also 

 be caused by currents. In September 1935 during the expedition of the Sadho along the eastern 

 shores of Franz Josef Land, I observed variations of pancake ice. Individual elements were angular 

 in form, and the surface of the ice resembled crocodile skin in design. Evidently, such forms of 

 pancake ice are created in connection with the breaking of nilas by interference waves, and naturally 

 form thicker ice. 



Small ridges along the edges of the pancake ice discs, which form due to the friction of one 

 disc against the other, are characteristic. This gives it the appearance of flat frying-pans. 



Pancake ice discs, gradually thickening and freezing together, finally form more or less ex- 

 tensive folds of continuous ice, in which the ridges along their edges, which are 1 to 2 cm higher 

 and whiter than the discs themselves, give the surface of the freezing sea an appearance of being 

 covered by a white net. 



With wind and strong agitation, the lard ice gathers into whitish fragments called "brash." This 

 gathering is especially characteristic along the crests of waves. During the Sadko expedition in 

 1935, with an air temperature of -6° and a strong wind, I observed the formation of brash accumu- 

 lations stretched out behind the wave crests in the direction of the wind. It seemed that brash 



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