NATURE OF THE STREAM 141 



is concentrated and in the east is broad, slow, and diffuse. 

 Thus the Gulf Stream runs northward through the western 

 Atlantic at a pace which may sometimes exceed five knots, 

 while the Canaries Current, running in a southerly direction, 

 is very wide but barely noticeable. A stronger current in the 

 west is also found in the North Pacific, where the Japanese 

 Current, the Kuroshio, takes the place of the Gulf Stream; 

 in the Indian Ocean, with its strong Agulhas Stream; and in 

 the South Atlantic, where the Brazil Current flows. The only 

 exception seems to be the Humboldt Current in the eastern 

 South Pacific. The explanation for this comes from the work 

 of Henry Stommel, Walter Munk, and others who have stud- 

 ied the balance of forces working on the whole system. And 

 here is Munk's interpretation: 



The spin of the winds, which blow outward in roughly 

 spiral fashion from the mid-ocean center of high pressure, 

 keeps the water moving in its circular path, but there are other 

 forces acting that are different on the two sides of the ocean. 

 We have spoken of the CorioHs force and of the right-hand 

 twist it gives to movement in the northern hemisphere. This 

 effect is not constant, but becomes greater in the higher lati- 

 tudes — it becomes increasingly powerful as the western cur- 

 rent flows northward from the equator; whereas in the eastern 

 part of the ocean the Stream runs south and the Coriolis pull 

 becomes less. When the opposing spin of water friction is 

 taken into account, a mathematical analysis shows that the 

 ocean circulation can become stable and balanced only if the 

 current becomes concentrated in the west. Shorn of its tech- 

 nicalities this new wind theory means that there must be a 

 broad, slow Canaries Current in the east and a narrow, fast- 

 flowing Gulf Stream in the west, and that this would be so 

 even if the Caribbean were dammed up and the water no 

 longer forced to flow through the Straits of Florida. 



Although Munk's work is the first successful attempt to 



