What phenomenon occurs when a layer of cold air is trapped near the ground?

The phenomenon that occurs when a layer of cold air is trapped near the ground is known as temperature inversion. During a temperature inversion, the typical decrease in temperature with altitude is reversed, resulting in warmer air sitting above cooler air. This situation can lead to several consequences, such as poor air quality since pollutants are trapped within the cooler air layer and do not disperse easily. This lack of vertical mixing can cause fog and a reduction in visibility.

In contrast, thermal stratification generally refers to the layering of water at different temperatures, which is more relevant in aquatic environments. Barometric pressure increase doesn't specifically describe the trapping of cold air; it relates to changes in atmospheric pressure that can occur for various reasons. Wind shear refers to the change in wind speed and direction with height and is not directly associated with the phenomenon of cold air being trapped. Thus, temperature inversion clearly explains the scenario of cold air being trapped near the ground.