Which of the following is a characteristic of a warm front as it approaches?

A warm front is characterized by the gradual ascent of warm air over cooler air. As this front approaches, the warm air pushes the cooler air upwards, leading to specific meteorological patterns. One of the key characteristics associated with a warm front is the lowering of the cloud base. As warm, moist air rises, it cools and condenses into cloud formations at progressively lower altitudes.

As the warm front gets closer, the cloud base can lower due to the increasing moisture in the air and the cooling effect that occurs as the warm air rises over the cooler air mass. This often results in a blanket of stratiform clouds, which can lead to precipitation as the warm air continues to rise and cool. The presence of these clouds and the resulting impact on visibility and weather conditions are significant as the warm front approaches.

In comparison, a rising atmospheric pressure typically occurs in advance of a warm front, while cumulonimbus clouds are more associated with cold fronts and severe weather conditions. Clear skies with isolated cumulus clouds do not accurately describe the typical cloud patterns observed with an approaching warm front.