It follows from formula (4) that if at the initial time moment the temperature of the sea sur- 

 face is everywhere the same, it wUl change with time so that the change would be greater where 

 the differences between the water and air temperatures are greater. This difference will be the 

 greatest at the coast, no matter whether a colder or warmer offshore wind is blowing, and there- 

 fore, it is natural that even with all the other conditions being equal (equal depths, equal vertical 

 distributions of temperature and salinity) the coastal water will be heated more rapidly by warm 

 winds and will cool more rapidly with cold winds. 



So far we have discussed only the variation of the temperatures of sea and atmosphere. How- 

 ever, the temperature difference is associated with more than the process of heat exchange in the 

 restricted sense of the word. The temperature difference also affects the effective radiation, 

 evaporation and condensation, and therefore, the derived formulae, appropriately modified, are 

 applicable to these processes. 



Of special significance is the case of a cold offshore wind. In consequence of the low tem- 

 perature, the air contains only a small amount of water vapor. As the air leaves the coastline for 

 the sea, the moisture deficit is great and the evaporation (and, consequently, the cooling of the 

 sea) is intense. As the distance from the coast increases, the absolute moisture of the air grad- 

 ually increases but, with it, the air temperature Increases rapidly. Therefore, with distance from 

 the coast, the moisture deficit either decreases slowly or may even increase to a degree. But 

 since the speed of evaporation is directly proportional to the moisture deficit, the evaporation rate 

 can, at a cold offshore wind, be considerable, even for out in the open sea. 



LITERATURE: 77. 



Section 21. The Effect of Ice on tfie Atnnosphere 



Ice has certain distinctive qualities in comparison with the sea and the land. The ice, like 

 the sea, appears to be an inexhaustible source of moisture for the atmosphere. In winter, with 

 negative air temperatures, the ice behaves like the land with respect to the atmosphere. The 

 temperature of the upper surface of the ice determines the temperature of the contiguous air stra- 

 tum, if the latter is measured in oceanological coordinates, i.e. , if temperatures of the same air 

 mass are determined. The temperature of the lower air strata is very near that of the upper sur- 

 face of ice. In summer, with positive air temperatures, the air masses moving over the ice may 

 be so well heated that the temperature of the upper surface of ice remains unchanged — near the 

 thawing temperature . 



In this connection, the seasonal changes of air temperature over the ice differ from the 

 seasonal changes of temperatures over the open (not frozen) sea and over the continent. The 

 sasonal march of temperature is illustrated in figure 10: 1 — over open sea (southwestern part of 

 the Barents Sea), 2 — over the ice of the Kara Sea (Ostrov Myedineniya) and 3 — over the conti- 

 nent (Igarka). 



Insofar as the temperatures of the sea and ice are always very low in the arctic, it very 

 frequently happens that the air temperature increases with altitude (temperature Inversion) . 



In winter during clear weather, when the back radiation is intense, the temperature of the 

 upper surface of the ice can be below the temperature of the adjacent air strata by a few degrees, 

 which is the winter inversion. In summer, the warm air moving over cold ice is cooled, and thus 

 the summer Inversion is formed. 



45 



