CHAPTER V 



EXPLORING THE UPPER AIR 



I HE prime object of the Green- 

 land Expeditions from the Uni- 

 versity of Michigan has been the 

 study of the winds over the great 

 ice-cap, the glacial anticyclone or 

 North Pole of our wind system. 

 The first problem which faced us 

 was to select a place for the observing station 

 which would be sufficiently near to the ice-cap to 

 have the winds about it dominated by this North 

 Polar circulation, and it was not at the time known 

 how far outside the ice margin the outblowing 

 winds extend. 



We had come provided with equipment for a 

 study of the upper air in addition to the usual 

 studies carried out upon the ground; and for the 

 upper air work two quite distinct types of balloons 

 were required. One type, the pilot balloon, gives 



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