The colder air mass is heavier than the warmer air, and so the lighter, warmer air rises over the top of the heavier, cooler air.

较冷的气团比较热的空气重，因此较轻的空气——暖空气上升到较重、较冷的空气上方。

For example, if the cold air mass is feeling feisty and moves in on a warm air mass, we get a cold front.

例如，如果冷气团感觉活跃并进入暖气团，我们就会得到冷锋。