Which type of front is characterized by a gradual transition between air masses?

A warm front is characterized by a gradual transition between air masses. This occurs when warm air moves over cold air, leading to a slow and steady uplift of the warm air. As this happens, the warm air gradually cools, which results in the formation of layered clouds and often gentle precipitation, typically seen in the form of rain that may last for an extended period.

In contrast, cold fronts tend to have a more abrupt transition, where denser cold air pushes under the warm air, causing more intense weather changes along a sharper boundary. Stationary fronts represent a standoff between two air masses, leading to prolonged weather changes that can be similar to both warm and cold fronts but do not have the same gradual transition. Occluded fronts occur when a cold front overtakes a warm front, producing complex and often varied weather patterns rather than a smooth transition. Therefore, the defining characteristics of a warm front make it the correct choice for identifying the type of front with a gradual air mass transition.