hummocks which run under the water and that the lower points of the lower lumps stretch deeper 

 than the tubes reach. " 



LITERATURE: 11, 23, 77, 88, 101, 105. 



Section 102. Snow Cover on Ice 



The snow which falls on the arctic ice in winter, due to the low temperature of the air, which 

 prevails at this time, belongs to the type of wild or gritty snow. Often it includes a mixture: crys- 

 tals of sea salt and specks of dust of ground origin. 



Crystals of sea salt fall in the snow in two ways. First, as we have seen, in the leveling of 

 the combs of waves, the spray often evaporates into the air and particles of salt are transferred by 

 the wind for great distances. They serve as fine kernels of condensation and crystallization and 

 finally fall with precipitation. Secondly, the surface of young ice (forming especially at low temper- 

 atures) is covered with brine, which, freezing, forms salty hoar frost or ice flowers, sometimes 

 covers great areas, and consists of crystals of ice upon the tips of which are attached crystals of 

 salt. During strong winds, these crystals are removed from a spot, rise, and are mixed with the 

 snow particles which are already in the air. They then fall, appearing like salted snow. 



Nansen noted that in some places, the snow on the ice of the Arctic Basin was extremely 

 salty, and it was not possible to use it for checking the zero point of his thermometers. According 

 to the observations of the Zarya, snow was sometimes so rich in salt that the water from it was 

 entirely unsuitable for drinking. In other places, the prisms of salt were discovered easily by the 

 turbidity of the melted water with the addition to it of some drippings of silver nitrate. 



Dust specks of ground origin which fall on the surface of the ice are received chiefly during 

 erosion and freezing out from tundra and clay-fan soils. These soils with drying give a thin dust 

 which is easily transported great distances by the wind. Such dust forms greyish, yellowish or 

 brownish deposits on the ice. It is clear that this dust is especially noticeable on littoral ice. Ac- 

 cording to the observations of the Zarya, the ice, free from snow and at the same time covered 

 with dust, was encountered in the Buorknaya Gulf at a distance 15 miles from the shore. During the 

 spring of 1939, at the time of a flight along the coast of Yamal, we saw signs of dust extending to the 

 west from the hills of tundra which were free of snow. 



The fate of snow depends on the surface upon which it falls. 



If the snow falls on a comparatively warm surface of the sea which is clear of ice, then when 

 melting, it cools the surface layers of the sea. 



If snow falls on a surface of the sea either cooled earlier or cooled by the snow itself to a 

 freezing temperature, the fallii^ snow flakes appearing as kernels of crystallization accelerate the 

 process of ice formation. With a great quantity of snow, as we have seen, a particular form of ice 

 may even be caused, (snezhura). 



If the snow falls on cold ice, covered with brine, then, soaking the salt, it freezes solidly to 

 the cold ice, forming a characteristic dull grainy crust. 



During low air temperatures, as was already discussed, the snow appears odd or gritty. 

 Falling on the surface of smooth ice, it forms a thin, badly connected cover which is easily blown 

 away by the wind. As a result of this, (according to observations of the Zarya ) huge spaces of 



274 



