52 : The Atlantic 



ate and deep waters of any ocean. Atlantic intermediate water is 

 formed off Newfoundland and sinks and moves south slowly under 

 the surface currents. Atlantic deep bottom water is formed on either 

 side of south Greenland. It sinks to the very bottom of the ocean and 

 begins a movement southward over the bottom surface that is so slow 

 it has been described as a "creep"; but eventually it will arrive near 

 the equator. 



To these must be added a very special type of water known as the 

 Mediterranean which, as we might expect, originates in that sea; but 

 we should hardly expect it to form a distinct level or carpet in the 

 Atlantic spreading out in all directions and being recognizable almost 

 as far as Bermuda. To understand how this is so, we must recollect 

 the peculiar conditions in the Mediterranean. 



If you were looking from the Rock down on the Straits of Gibral- 

 tar, the only connection between the Atlantic and the Mediterranean, 

 you would observe that the waters seem to be flowing continually 

 from the Atlantic into the Mediterranean and that so far as you could 

 see, there would be practically no water escaping from the Mediter- 

 ranean into the Atlantic. 



The mystery is solved — as mysteries so often are — ^by looking be- 

 neath the surface. Here we should find that at greater depth there 

 was a flood of water pouring out of the Mediterranean into the Atlan- 

 tic. What happens here is that the Atlantic water coming in is light 

 and not very salty. The column of fresh water flowing into the Medi- 

 terranean is not very great. On the other hand, the region is warm 

 and sunny, therefore the evaporation is great. 



The incoming Atlantic water, therefore, spreading out on the sur- 

 face evaporates and becomes saltier and heavier and so sinks down to 

 form a carpet of saltier and heavier water and finally to form the 

 stream that rushes out of the Straits of Gibraltar under the lighter 

 Atlantic surface water. It finds its own level of temperature and of 

 saltiness and spreads out across the Atlantic in a fanshape pattern. 

 This Mediterranean water keeps its identity amid the other Atlantic 

 waters and has been identified off Bermuda. 



The right-handed or clockwise circulation of currents in the North 

 Atlantic is of course due to the rotation of the earth about its axis. 

 The same force that produces the right-handed swerve in the North- 

 ern Hemisphere will produce a left-handed swerve across the equa- 

 tor in the Southern Hemisphere. The South Atlantic winds and cur- 

 rents are therefore very similar in general pattern to those of the 



