In turn, in the course of time, when there is a temperature decrease, surface brine partially 

 forms crystals of pure ice (due to this, its concentration gradually increases) and it seeps 

 downward. 



The brine on the surface of the young level ice formations is one of the very characteristic 

 phenomena. Since brine remains in a liquid state even at very low temperatures the surface of 

 young ice is always moist. During the expedition on the Vega, Nordenskjold observed surface 

 brine containing 15. 7 o/oo chlorides and which remained moist for a week when the air temperature 

 reached -32°. 



According to the observations of the expedition on the Zarya, the fresh ice on the polynyas 

 which had closed in November (when the air temperature was about -30°) was covered with a moist 

 brine during the first days of its existence, making sledging difficult. Sledging over the brine was 

 just as difficult as over sand. 



If the air temperature decreases still further, the entire surface brine freezes, turning into 

 cryohydrates and ice — a mixture of ice crystals and salts. During this, small snow-white bushes, 

 called "ice flowers, " form on the ice surface. These flowers resemble heavy frosts on grass. 

 According to Wesrprecht, these bushes, which are sometimes 3-4 cm high, consist of thin ice 

 needles carrying the separated salts on the ends of the crystals. 



The ice flowers are very brittle formations, and are easily blown off by the wind, turning Into 

 fine salt dust. This dust is sometimes carried for great distances before it again falls on the 

 surface of the ice along with the snow. 



During each rise in temperature, the salt crystals turn into a solution and the ice surface 

 again becomes moist. 



The snow, falling on the surface of the young ice moist with brine, is saturated with brine to a 

 slight height. During this, the upper snow layers do not undergo any changes and keep the brine from 

 freezing during low airtempteratures. Thus, surface brine is preserved for a long time, determining 

 "ice moisture. " The expedition on the Zarya observed that during a frost of -20°, movement over 

 freshly fallen snow on young ice left clear, wet traces of a steel gray or gray-yellow color. 



When there is a further decrease in temperature, the mixture of snow and brine soldifies and 

 forms a thin, non-transparent, snow-white and very salty scum 2 to 3 cm thick on the ice surface, 

 which differs sharply from the glass-like, dull and semi-transparent mass of ice. 



The mass of the snow and the brine frozen together forms a rougher surface in comparison 

 with the surface of the ice which had solidified without snow, and especially in comparison with ice 

 formed In the fresh-water reservoirs on Arctic ice. The latter is usually as smooth as glass, and 

 snow is not retained on it. 



It has already been pointed out that the salt cells which are surrounded on all sides by pure 

 ice (figure 53), as the ice thickness increases, assume the greatest importance for their salinity. 

 The shape of these cells can be extremely variable. 



As Bruns indicates, an understanding of sea ice structure can be given by measuring its 

 electrical conductivity. Actually, the electrical conductivity of pure ice varies within the limits of 

 lOlO to 10-12 reciprocal ohms. But according to Bruns' calculations, the electrical conductivity 



142 



