Which factor influences the characteristics of a cold front?

The characteristics of a cold front are primarily influenced by a cold air mass pushing under a warm air mass. This process occurs because cold air is denser than warm air, causing the denser cold air to advance and displace the lighter warm air upwards. As the warm air rises, it cools and can condense into clouds and precipitation. This dynamic creates distinct weather patterns typical of cold fronts, including the potential for thunderstorms and a noticeable drop in temperature following the front's passage.

Other options may describe different atmospheric phenomena but do not directly characterize the dynamics of a cold front. For instance, while warm and humid air rising can relate to the presence of a warm front, it does not apply to the characteristics specifically associated with cold fronts. High-pressure systems are more related to stable weather conditions, while equilibrium between air masses does not capture the active and often tumultuous nature of a cold front's movement and the resulting weather changes.