This column is provided as a public service by the Geophysical Institute, University of Alaska Fairbanks, in cooperation with the UAF research community. T. Neil Davis is a seismologist at the institute. We keep hearing about the inversion over Fairbanks. Normally, the air near the ground is warmer than the air at higher altitude.
Cold air is heavier than warm air.
Thus once an inversion forms, the air is very stable. Mixing that would normally occur by the rising of warm air is inhibited. Consequently pollutants such as carbon monoxide, sulfur compounds and ice fog remain trapped near the ground when there is an inversion.