Temperature inversion is a meteorological phenomenon where a layer of warm air traps cooler air near the ground. This occurs when the atmosphere is stable, often during clear nights when the ground cools rapidly. As a result, the cooler air, which is denser, gets trapped below the warmer air, preventing it from rising. This situation can lead to poor air quality, as pollutants and fog can become trapped in the cooler air layer. Temperature inversions are common in urban areas and valleys, where they can contribute to smog and other environmental issues, affecting the health of residents and the ecosystem.