In meteorological terms, what is defined as a "front"?

A front is specifically defined as a boundary between two different air masses, which are distinct regions of the atmosphere that have different temperature, humidity, and density characteristics. When these air masses meet, they do not immediately mix; instead, they create a transition zone where various weather phenomena can occur. The nature of the interaction between the differing air masses at this boundary influences weather conditions significantly, often resulting in changes such as precipitation, temperature shifts, and wind direction.

Understanding this concept is crucial in meteorology because it helps to predict weather changes. For instance, a cold front, which is a boundary where a colder air mass is moving into a warmer air mass, can lead to the development of storms and abrupt weather changes. Similarly, warm fronts may produce a more gradual change in weather, often bringing prolonged periods of rain.

In contrast, the other options, while related to atmospheric phenomena, do not represent the definition of a front in meteorological terms. A zone of high pressure typically indicates stable weather conditions rather than a boundary between air masses. A line of thunderstorms could occur along a front but does not define what a front is. A type of severe weather, while it may happen due to the presence of fronts, is not itself a front. Thus,