What weather phenomenon is characterized by warm air being on top of cold air?

The weather phenomenon characterized by warm air being on top of cold air is known as a temperature inversion. In a temperature inversion, the typical pattern of temperature decrease with altitude is reversed; instead, the warm air acts as a cap over the cooler air below. This scenario can lead to various atmospheric effects, such as trapping pollutants and moisture, which can result in fog or smog in urban areas.

Temperature inversions are significant in aviation because they can affect visibility and potentially lead to hazardous flying conditions. Understanding this phenomenon is essential for pilots, as it influences both weather patterns and the performance of aircraft. The presence of a warm layer above cold air can also suppress vertical mixing, stabilizing the atmosphere, which may lead to prolonged periods of undesirable weather conditions.