Here's a breakdown:

* Air Masses: Large bodies of air with relatively uniform temperature and humidity.

* Fronts: The transition zone, or boundary, between two different air masses.

There are four main types of fronts:

* Cold Front: A cold air mass pushes into a warmer air mass, causing rapid lifting and cooling. This can lead to thunderstorms, heavy rain, and strong winds.

* Warm Front: A warm air mass pushes into a colder air mass, causing gradual lifting and widespread precipitation.

* Stationary Front: Neither air mass is strong enough to push the other, leading to prolonged periods of rain and cloudiness.

* Occluded Front: A faster moving cold front overtakes a slower moving warm front, forcing the warm air aloft. This can bring heavy precipitation and cooler temperatures.

Let me know if you have any other questions about fronts or air masses!