Answer:
Gravity
Step-by-step explanation:
Air pressure (or atmospheric pressure) is the weight that air exerts on the earth's surface.
Its occurrence is mainly related to gravity and its influence on gaseous molecules that make up the atmosphere.
Thus, an atmospheric pressure changes according to altitudes and air temperature conditions.
The higher the altitude of a particular relief, in other words, the higher it is relative to sea level, the lower the atmospheric pressure.
This is because the force of gravity keeps most of the air close to the surface, which explains why large mountain ranges have a thinner air environment.