An atmospheric condition in which the air temperature rises with increasing altitude, holding surface air down and preventing dispersion of pollutants: Atmospheric inversion is a departure from the usual increase or decrease of an atmospheric property with altitude.

Atmospheric inversion usually refers to an increase in temperature with increasing altitude, which is a departure from the usual decrease of temperature with height.

In other words, atmospheric inversion is a reversal in the normal temperature lapse rate, the temperature rising with increased elevation instead of falling.

Usually within the lower atmosphere (the troposphere), the air near the surface of the Earth is warmer than the air above it, largely because the atmosphere is heated from below as solar radiation warms the Earth's surface, which in turn then warms the layer of the atmosphere directly above it.