What best describes the conditions necessary for Frontal Fog to form?

Frontal fog forms when warm, moist air is lifted over a frontal boundary, typically a cold front. As the warm air rises, it cools, leading to condensation and the formation of fog. This lifting mechanism is crucial for the fog to develop because the cooling of the air as it ascends allows the water vapor to condense into tiny water droplets, creating fog.

High humidity is important in this process since it indicates a significant amount of moisture in the air that can condense when the temperature drops. If humidity is low, there wouldn’t be enough moisture available to form the fog upon cooling. Therefore, the condition that warm air is lifted over a front is integral to the development of frontal fog.