As you go higher in the atmosphere, the air pressure decreases. This is because the air molecules are pulled towards the Earths surface by gravity, and as you move away from the surface, there are fewer air molecules above you to exert pressure. The decrease in air pressure with altitude occurs due to two reasons: the gravitational attraction between the Earth and air molecules, and the compression of air molecules due to the weight of the air above them.

Atmospheric pressure is measured in units of force per unit area, such as pounds per square inch (psi) or pascals (Pa) . The pressure exerted by the air in the atmosphere is greater close to the Earths surface and decreases as you go higher above the surface. For example, at sea level, the atmospheric pressure is around 1013 hPa, while at an altitude of 5,000 meters, it is around 500 hPa.

The decrease in air pressure with altitude has important implications for weather and climate. For example, low-pressure systems are associated with rising air, which can lead to cloud formation and precipitation. High-pressure systems, on the other hand, are associated with sinking air, which can lead to clear skies and dry weather.