Air mass

An air mass is like a big bubble of air that travels around in the sky. Different air masses can be really different - some might be cold and dry, while others might be warm and wet. Just like people, air masses come from different places, and where they come from can make a big difference in how they feel.

For example, imagine that you're standing in a really hot place - maybe at the beach on a hot summer day. The air all around you is hot and humid, which means there's lots of moisture in the air. Now imagine that you walked into an air-conditioned building - the air inside the building is probably cooler and less humid than the air outside.

In the same way, when an air mass moves into a new area, it can bring different weather conditions with it. If a cold and dry air mass moves over a warm and wet area, it might suck up all the moisture and leave the area dry and chilly. But if a warm and wet air mass moves over a cold area, it might cause thunderstorms and lots of rain.

So when we talk about air masses, we're really talking about big bubbles of air that can affect the weather in different ways depending on where they come from and where they go.