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      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
   
   
    | q | 
    The wintertime circulation over 
     | 
     | 
   
   
     | 
   
   
     | 
    the South Pole is characterized 
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     | 
   
   
     | 
    by a gigantic whirlpool of cold 
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     | 
    and dense air, called the polar 
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     | 
    vortex. 
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     | 
   
   
     | 
   
   
    | q | 
    The cold and dense cold air in 
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     | 
    the middle of the vortex is 
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     | 
   
   
     | 
    subsiding. 
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     | 
   
   
    | q | 
    The sinking air carries cloud 
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     | 
    particles along with it. 
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     | 
   
   
     | 
   
   
    | q | 
    Remove odd nitrogen from the 
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     | 
   
   
     | 
    stratosphere. 
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     | 
   
   
     | 
   
   
    | q | 
    Very little ozone and odd 
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     | 
    nitrogen can be brought into the 
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    south pole. 
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     |