latitudes, on the contrary, precipitation dominates over evaporation, and a constant dilution oc- 

 curs. The general equilibrium of moistxire is maintained by sea currents. 



In order to judge the balance of water and salinity in individual seas of the World Ocean, let 

 us adopt the following assumptions: 



1. the volume of water in a given sea is constant; in other words, the mean water level does 

 not change; 



2. the mean salinity of the given sea does not change; with such assumptions, we have the 

 following equation for the required balance of water masses: 



precipitation + continental runoff + water Influx from other basins = evaporation + water out- 

 flow to adjacent seas. 



If the pure water balance in this equation is precipitation + continental runoff — evaporation, 

 which is designated by F, we have the following formula of water balance: 



V^ + F = V., (1) 



where [/^ = the volume of water flowir^ from adjacent seas, 



[/„ = the volume of water flowing out of the given sea. 



Depending upon the relative magnitudes of the factors constituting the pure water balance, it 

 can be either negative or positive. In the first case we may have a positive water exchange of a sea 

 with the ocean (the influx of ocean waters exceeds the outflow of the given sea). In the second case 

 there is a negative exchange. A typical example of the first case is the Mediterranean Sea; a typ- 

 ical example of the second is the Black Sea. 



In order to preserve the constancy of the mean salinity of a sea (neglecting the volatilization 

 of salts into the atmosphere and their sedimentation on the bottom of the sea), the following equation 

 is needed: 



V,S, = V,S„ (2) 



in which Si= salinity of the water flowing from the ocean, 



So- salinity of the water flowing out of the given sea. 



It follows from equation (1) that if the pure water balance of a given sea is 0, i.e. , if precipitation 

 plus continental runoff exactly equals evaporation, then 



V, = V„ (3) 



whence, on the basis of equation (2) we have 



S, = S,. (4) 



If Si is greater than ^2 , the water exchange with other seas is negative; if ^i is smaller than S2 , 

 the water exchange is positive . 



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