DECATUR, Ill. (WAND) -Â In normal weather, air gets cooler with elevation. Warm air near the ground rises, mixes with cooler air above it, and this helps spread out clouds, smoke, and pollution.
A temperature inversion is when that pattern flips.
A layer of warm air sits on top of cooler air near the ground, like a lid on a pot. Because warm air is lighter, it prevents the cooler air below from rising. When this happens, air near the ground gets trapped. In tonight and tomorrow's case, the moisture trapped is in the form of clouds. There can also be spotty drizzle in the morning.  Regardless of the clouds, mild weather will continue to advect in from the west.Â
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