give me an example of front – a boundary between two or more air masses
An example of a front - a boundary between two or more air masses - is a cold front.
A cold front occurs when a colder air mass advances and replaces a warmer air mass. As the cold air mass moves into an area previously occupied by warmer air, it creates a sharp boundary between the two air masses. This boundary is the front.
For instance, imagine a scenario where a cold air mass from the north is moving southward and encounters a warm air mass from the south. As the two air masses meet, the colder air aggressively wedges underneath the warmer air, forcing the warm air to rise rapidly. This uplift of warm air causes the formation of clouds, leading to precipitation and potentially thunderstorms. The front, in this case, would be the boundary separating the warm air mass in the south from the advancing cold air mass in the north.