What happens in a warm front? A. A warm air mass becomes a cold air mass as it moves.
B. A warm air mass catches up to a moving cold air mass, sliding
over it.
C. A cold air mass comes in under a warm air mass.
D. A warm air mass collides with a stationary cold air mass, and
slides under it.

A warm front forms when a warm air mass pushes into a cooler air mass, shown in the image to the right (A). Warm fronts often bring stormy weather as the warm air mass at the surface rises above the cool air mass, making clouds and storms. ... As the front passes over an area, the clouds become lower, and rain is likely