Section 46. Classification of Ice According to Size and Form 



The ice found in the sea is differentiated, aside from its origin and age, according to its size 

 and form . 



During the winter, due to the movement of ice caused by some reason or another, and due to 

 temperature changes, there occur: 1) an increase in the vertical size of the ice (due to growth and 

 rafting), 2) an increase in the horizontal size (due to the fusion of separate ice formations), and 3) 

 a decrease in the horizontal size due to fissures which arise with temperature changes (thermal 

 fissures), with paddle phenomena (paddle fissures), and with compression (pressure fissures). 



During the summer, there occur: 1) a decrease in the vertical size (as a result of melting 

 from above and below and a deterioration of rafting formations) , 2) an increase in the vertical size 

 (due to rafting), and 3) a decrease in the horizontal size (as a result of breaking and rafting). 



Ice formations in which the horizontal measurements exceed considerably the vertical ones 

 are called "icefields" and "floes. " 



Pack ice, which is the most extensive in area (more than 2 km in length) is called a "large 

 ice field. " It is formed when large areas of fast ice break loose from the shore, and above all, 

 when ice formations smaller in area are fused together (figure 37) . 



Figure 37. Ice fields. 



Some large ice fields possess such a level upper surface and such thickness that they permit 

 landings by heavy airplanes on them. Such fields are called "airdrome fields. " 



Ice fields having an extent of 200 m to 2 km are called "small ice fields. " They develop 

 either as a result of fusion of smaller formations or as a result of a break-up of large ice fields. 



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