where d = heat of evaporation, 



A. = heat of fusion, 

 h = height of melted layer of ice, 

 s = height in centimeters of layer of precipitation, 

 At = difference in temperature of precipitation and temperature of ice surface, which 

 is considered positive if the former is higher than the latter. 



Substituting in equation (4), we obtain 



Qr+Qa= dD + US. — zM , (9) 



or 



As we have already noted, since the quantity of precipitation in the artic is small and the 

 temperature of the precipitation is little different from the temperature of the sea surface, the 

 effect of liquid precipitation falling on the surface of the ice consists not so much of a heating action 

 as of a decrease in the albedo of the ice. As for the difference between evaporation and conden- 

 sation, if it is considerable, then melting is lessened. 



Kizmin has shown that in the case of glaciers, on a warm, dry and sunny day when humidity 

 is relatively low there is less melting than on a similar warm and sunny day with air condition 

 close to saturation. , 



Ignoring precipitation, Kuzmin obtains from equation (10): 



Qr I Qa 



dD+US.^ dD-JfUB., 



^^ + ^^^" . = 1, (11) 



or 



K,+Ka=l, (12) 



where K^ = coefficient of radiational influence, 



K^ = coefficient of thermal influence of air. 



Kuzmin further shows that under the most favorable conditions of atmospheric transparency 

 and with cloudless weather the layer of ice which is melted from radiational heat may amount to 4 

 to 5 cm a day on the southern glaciers of the USSR. If the coefficient of thermal influence of air is 

 equal to .5, then the total daily melting m.ay reach 8 to 10 cm. Judging from direct observations, 

 this is a limiting value. 



In cloudy weather the coefficient of thermal influence of air may very nearly approach unity. 



We note that from equation (12) it follows that 



(13) 



K Qr' 



Concerning the value of this ratio, Kuzmin notes that two surface conditions of glaciers are 

 well known. In the first case, when warm and cloudy weather has set in, melting occurs in such a 

 way that the glacier surface becomes smooth and at the same time dirty, covered on top with 



313 



