is weak and plastic in consistency; and does not acquire its strength and 

 characteristic brittle nature until it has been cooled below 16°F. 



Young ice is hard and brittle. It frequently has some slight degree of 

 transparency and is generally 2 to 8 inches thick. Young ice has a sufficient 

 degree of hardness to bear light and medium loads. 

 Winter ice is one seasons growth. 



Polar ice is the thickest and heaviest form of sea ice more than one 

 year old. Undisturbed polar ice is about 12 feet thick on the average. 

 Rotten ice is ice that is disintegrating, regardless of its former condi- 

 tion. It is honeycombed and waterlogged and will not bear much weight. 

 The above is an outline of the complete sea ice cycle. The cycle may be 

 interrupted at any stage and set back to a previous stage or forward to the 

 final one. It is probable that only the ice formed well within the polar 

 regions undergoes the entire cycle. The stages are gradational and difficulty 

 will sometimes be encountered in making distinctions. It is quite usual to 

 find adjacent ice in two or more stages of development, particularly at 

 the higher latitudes. In the Weddell Sea on more than one occasion the 

 formation of pancake ice was observed to take place during the melting 

 and decay of pack ice, although the occurrences are rare. 

 ALIMENTATION (of glaciers) : (V.C.) — A combination of processes 

 contributing to the growth and maintenance of glaciers; sometimes 

 termed the nourishing of glaciers. While accumulation of snowfall is 

 usuallv the principal factor, condensation of water vapor into its various 

 solid forms and snowslides are important agents. In parts of the 

 Russian Arctic, e.g., Novaya Zemlya. condensation is the major factor. 

 ALPINE GLACIER: 1 1 1. A. 2b.)— Valley glacier. 

 ANCHOR ICE: (I.B.l.d.) — Bottom ice. 

 ANTARCTIC WHITEOUT: ( V.B.)— Cf. arctic whiteout. 

 APRON: 



(1) (I.C.2.)— Ram. 



(2) ( 1 1. A. 3. e.)— Ice apron. 



(3) (II.A.l.a.) — An outspread alluvial deposit with generally outward 

 slope, deposited bv a stream or streams in front of a glacier. 



ARCHED ICEBERG: (II.A.5.a.) — An iceberg eroded in such a manner 

 that a large opening at the water line extends horizontally through the 

 iceberg forming an arch. See iceberg. ( Figs. 89, 94.) 



ARCTIC PACK: (I.A.3.e.)— Polar ice. 



ARCTIC SEA SMOKE: (V.B.)— Frost smoke. 



ARCTIC WHITEOUT: (V.B.)— A peculiar condition affecting visibility 

 caused by a snow cover obliterating all landmarks and accompanied by 

 an overcast sky or cirrostratus and/or altostratus clouds. No shadows 

 are cast and the picture is one of an unrelieved expanse of white. Earth 

 and sky blend so that the horizon is not distinguishable. This condition 



