Question

Why does air pressure decrease the higher you get in altitude?

Answer 1

Less air molecules in higher altitudes, exerting a smaller force on the layer below. The force is air pressure.

Explanation:

Each layer of atmosphere exerts a force on the layer below it. Due to the weight of the entire air column of air exerting a force on the layer below, the bottom layer becomes compressed.

As the altitude increases, the amount of air above that level becomes smaller and smaller. Therefore, exerting a smaller force of air just below it.

The force becomes air pressure.

Hope this helps :)