The South Polar Lands 
HILE THERE MAY BE some ambiguity about the term 
W cota lands” as applied to the Arctic, there is none 
in the Southern Hemisphere. The Antarctic Continent 
lies almost wholly within the Antarctic Circle, which 
roughly parallels the isotherm of 32° F. for the warmest 
month. 
There is no intimacy between Antarctica and other land 
masses as there is between all of the other continents. You 
might start at Cape Horn and travel to all the rest of the 
continental lands never crossing more than sixty miles of 
shallow seas, whereas most of the lands around Antarctica 
are separated from it by as much as two thousand miles of 
water. The narrowest oceanic area, Drake Passage, is more 
than seven hundred miles wide. 
However, what is generally regarded as the most notable 
natural boundary relating to the totality of South Polar 
conditions roughly parallels the isotherm of 50° F. for the 
warmest month (the outer boundary of the Outer Polar 
Belt). ‘This is the Antarctic Convergence, an unbroken 
and rather sharply defined boundary around the continent 
whose position shifts slightly from season to season. ‘The 
Antarctic Convergence is caused by the fact that the cold 
waters of the northward-moving Antarctic intermediate 
current are denser than the sub-Antarctic waters and sink 
sharply below them with but little mixing. Sea and air 
temperatures, water analyses, the character of the plankton 
and the sea birds, all reveal this boundary. 
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