During which weather condition does warm air rise over cold air?

Warm air rises over cold air primarily during a warm front. In a warm front scenario, warm, moist air moves toward colder, denser air. As this warm air encounters the cold air mass, it is forced to rise gradually. This lifting process leads to the formation of clouds and precipitation in advance of the front, as the warm air cools and condenses as it ascends.

In contrast, a cold front comprises colder air displacing warmer air, which causes the warm air to rise more abruptly. A stationary front occurs when two air masses meet but neither moves, resulting in similar weather patterns without the active rising of warm air over cold air. An occluded front forms when a cold front catches up to a warm front, leading to complex weather patterns that don’t fit the straightforward warm air rising scenario. Therefore, the defining characteristic of a warm front is the gradual ascent of warm air over cold air, making it the correct answer.