Glacier ice in the form of icebergs if found in the Arctic Ocean between 120° west and 0-100° 

 east. The icebergs are carried out across Davis Strait into the Gulf Stream area by the Greenland 

 and Labrador currents. 



But glacier ice attains particular development and distribution in the South Polar regions. 

 Here, icebergs are found around the entire antarctic mainland, and reach to the southeastern 

 shores of the Americas. 



Sea ice is formed in the sea itself out of sea water. Salinity is its basic characteristic. With 

 time, sea ice becomes fresher, but even after it does become fresh (usable for the preparation of 

 food) , it preserves certain chemical properties which make it possible to distinguish it from river 

 or glacier ice. 



The main mass of sea ice has a greenish tuige; when there is a high content of snow and air 

 bubbles, it has a whitish, glass-like appearance. Marine ice, freshened and made more dense by 

 pressure, adopts a blue color in the course of time. 



According to areas of distribution and, above all, according to mobility, sea ice is divided 

 into two classes: "fast ice" and "pack ice. " 



"Fast, " or "immobile ice, " during the winter borders the continental shores, islands, and 

 also ice standing In shallows, which in this relation plays the role of islands. 



During the summer, fast ice usually breaks up, separates into different fields and floes, 

 breaks loose from the shore, and changes into the pack-ice classification. 



"Floating" or "drifting" ice is in constant motion both winter and summer due to the effect of 

 constant and periodic currents and the wind. 



Old drift ice of great thickness and solidarity, which is impenetrable by contemporary ice 

 greakers, even during the summer, is called "pack ice, " and fills the central part of the Arctic 

 Basin. 



Depending on the conditions under which it was formed, ice is divided into "grovm ice" and 

 "heaped ice". The thickness of the first increases exclusively due to low air temperatures. The 

 thickness of the second, in addition, is due to the rafting of one floe on another. Any ice formation 

 can occur at any time. 



Two groups of ice are differentiated according to age: 



1. Year-old ice. The following are differentiated in this group: "spring ice, " i. e. , the ice 

 which is formed in the spring before navigation. This is the youngest, thinnest, and warmest ice; 

 it hardly hinders navigation. After it follows "winter ice" and "autumn ice, " both of which are 

 older in age than the spring ice. 



2. Old ice, which includes ice which had existed a winter, a summer, and the following 

 winter. 



LITERATURE: 23, 62, 77. 



107 



