What is the atmospheric phenomenon when cool air is trapped near the earth by warm air?

The phenomenon where cool air is trapped near the earth's surface by a layer of warmer air above is known as a temperature inversion. This occurs when the normal atmospheric temperature gradient is reversed, leading to a situation where the cooler, denser air becomes trapped. This inversion can result in various effects, such as the trapping of pollutants and increased fog formation, since the warm air acts as a cap, preventing the cooler air from rising.

Inversions often occur during the night when the ground cools rapidly and the air adjacent to it loses heat. The warm air above does not allow this cooler air to mix, which can lead to stagnant conditions, significantly affecting weather and air quality. Understanding this phenomenon is crucial for predicting local weather conditions and recognizing its implications for aviation, as it can affect visibility and aircraft performance.