What term is used to describe the transitional zone between two different air masses?

The term that describes the transitional zone between two different air masses is "front." In meteorology, a front is defined as the boundary separating two air masses of different densities, temperatures, and humidity. This zone can lead to various weather phenomena, as the interaction between the two air masses can cause precipitation, cloud formation, and shifts in wind patterns.

Each type of front—such as cold fronts and warm fronts—represents specific characteristics of the air masses involved, with cold fronts often bringing colder air and warm fronts bringing warmer air. However, while these specific types describe certain conditions that occur at fronts, the broader term "front" encapsulates all such transitional zones irregularly, regardless of the specific air mass characteristics.

This foundational meteorological concept helps to explain many aspects of weather patterns and phenomena, making it crucial for understanding weather dynamics.