The three Greenland Expeditions of the University of Michigan (1926–29) were launched to study the meteorological conditions over and about the inland-ice dome, which so nearly covered the continent. The resulting studies depended upon pilot-balloons, supplemented in 1926 by registering balloons—ballons sondes. Earlier studies based on the observations made by explorers clearly indicated that over this northern ice-mass is located a fixed permanent and powerful anticyclone (glacial anticyclone), which as a reversing mechanism of the general circulation may be regarded as a northern wind pole of the earth in the same sense that the similar mechanism over the Antarctic continent may be looked upon as a southern wind pole. Earlier studies had also indicated that the success of the studies would depend very largely upon the location of the observing station. It was clear from the start that the meteorological records, particularly the direction and force of the wind made regularly at a few coastal settlements (generally partly sheltered within the mouths of fjords), would afford quite misleading indications. Thus the portion of Greenland selected for the studies was the area where the land ribbon surrounding the inland-ice is the widest, the Holstensborg district in the southwest, where this land stretches out to a width of close to a hundred miles.