Question

What kind of air front forms when a warm air mass meets the area of a cooler air mass?

Answer 1

With any front there is a warm and a cold air mass but it is the cold air that we look at not the warm air.

Explanation:

Since cold air is denser than warm air the movement of the cold air is what we look at. So a cold front is the leading edge of an advancing cold air mass and a warm front is the trailing edge of a retreating cold air mass.

Cold air is denser and therefore stays at the Earth's surface. If a warm air mass moves over a cold one it simple is lifted up over the cold air.

Here is a picture of a warm front to illustrate.

You can see how the warm air is lifted over the cold air. If the cold air is moving (it usually is) this becomes the trailing edge and is called a warm front.

Answer 2

Whatever air mass is moving determines the front

Explanation:

If cold air is moving, the front is a cold front. If warm air is moving, the front is a warm front. So if the warm air mass is advancing and moving towards a cooler area, it is a warm front. If the cold air mass is advancing and moving towards a warmer area, it's a cold front. It all depends on what air mass is moving.