ground inversion

A ground inversion is a meteorological phenomenon where a layer of cool air at the Earth's surface is trapped beneath a layer of warmer air. This is the opposite of the usual atmospheric condition where temperature decreases with altitude.1

Ground inversions typically form on clear nights when the ground rapidly cools due to radiation. This cooling causes the air in contact with the ground to become colder than the air above it. This can lead to fog formation if the surface air cools below its dew point.1

These inversions play a significant role in weather and air quality. They act as a cap, limiting the upward movement of air and thus trapping pollutants, dust, and smoke near the ground. This accumulation can lead to reduced visibility and contribute to air pollution episodes, as seen in cities like Los Angeles. Topography can also influence ground inversions, with cold air draining into valleys and creating thicker inversions at lower elevations.12