How do air masses move at a warm front?

In the context of meteorology, at a warm front, warm air is characterized by its ability to rise over a cold air mass. This is because warm air is less dense than cold air, which causes it to move upwards as it approaches the boundary between the two air masses. When a warm front occurs, the warm air gradually ascends above the cold air, leading to various weather phenomena.

This rising of warm air over cold air can result in the formation of clouds and precipitation, which is often steady and prolonged rather than the more showery phenomenon commonly associated with cold fronts. As the warm air ascends, it cools and can condense, forming the cloud layers typically associated with warm fronts. Observing this behavior is essential for understanding weather patterns and forecasting.

In contrast to the other options, the correct choice accurately describes the interaction between the two air masses at a warm front, highlighting the fundamental dynamics of atmospheric processes.