Along with the thermal influence of winds on the water, there is felt a mechanical effect which 

 results from the influence of wind, waves and current. The wave movement washes away the edges 

 of the water puddles while the current hastens the circulation and drives the individual ice chunks 

 from place to place, bumping them against each other . The circulation which is set up by the wind 

 in polynyas and puddles, where ice of various sizes and shapes is floating, may sometimes be ex- 

 tremely complex. I have often observed how, when the wind springs up in certain polynyas, the 

 first to start to move with the wind are the small ice floes having little inertia. Then, when the 

 larger ice floes have started to move with the wind, the small floes start to be carried against the 

 wind by the compensating current . This phenomenon continues until all the floes in the given 

 polynya are drive towards its leeward edge . 



LITERATURE: 62, 171. 



Section 112. Second Phase of Weakening of Ice 



The melting of ice is particularly increased when the air temperature, rising gradually, goes 

 above 0°. Then an increased absorption by the ice of atmospheric heat commences . This heat may 

 be either from heat of advection (carried hither from other regions of the sea or dry land) , or local . 

 From the very beginning of formation of water hollows on the ice, the sun' s heat is expended par- 

 tially on heating of the snow-water hollows and partially on evaporation. The air, which is satura- 

 ted with moisture in the evaporationprocess, is carried over the comparatively cold surface of the 

 ice, thus freeing the heat of condensation and causing the formation of fog and condensation of 

 moisture on the surface of the snow. The snow is reduced and "eaten away" ui this process. It 

 is obvious that this process is stronger when the water area is large in comparison with the surface 

 area of ice . 



From this there clearlyiB-ppears one more characteristic peculiarity of melting of the ice 

 cover . 



The first to start the thawing process is the "winter snow" which covers the ice, and the re- 

 sulting thaw water flows away into the snow puddles . After this process the ice surface is free of 

 snow. However, this phase lasts only a short time while the low winter temperatures are retained 

 in the surface layers of the ice. With passage of times, due to penetration of the ice by solar 

 radiation, the surface layer of ice starts to be destroyed and is changed first into porous ice and 

 then into granular ice not very different in appearance from decomposing snow. According to the 

 observations made by Gordienko on the ice of the Chuckchee Sea the average thickness of "snow" 

 formed from the ice varies from 10 to 15 cm. This "summer snow" is continually destroyed from 

 above by melting while its thickness is constantly increased from below on account of the penetra- 

 tion of atmospheric heat into the ice . Thus the thickness of the snow cover which is formed from 

 the ice as a result of melting remains more or less constant for each region. 



Along with thawing of the snow a strong desalinification or softening process of the higher 

 parts of the ice floes occurs . The fresh snow-water flowing off through the ice capillaries at first 

 freezes and thus blocks off the exits, but at the same time due to expansion on freezing, it causes 

 formation of cracks in the adjacent parts of the ice . With the later rise in temperature the freezing 

 of thaw water in the cracks ceases , and this thaw water commences to wash away very thoroughly 

 the brine from the salt cells of the ice. Thus, a softening of all parts of the sea ice which lie above 

 the water is gradually accomplished . 



As has already been shown, the melting process begins first on the more soiled parts of the 

 ice. In addition, the more saline the ice the greater its ability to absorb solar heat. We have 

 noted that as a general rule the ice near the thermal and dynamic cracks (which are formed at low 



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