How does the density of air affect surface pressure when more air is added?

When more air is added to a given volume at Earth's surface, the density of the air increases. Density is defined as mass per unit volume, so as more air is packed into the same space, the mass increases without changing the volume. Since atmospheric pressure is directly related to the weight of the air above a given point, an increase in the density of the air results in a corresponding increase in surface pressure.

This relationship is grounded in the fundamental principles of fluid mechanics, where pressure at a point is influenced by the overlying mass of fluid (in this case, air). Higher density means that for every cubic meter of air, there is more mass exerting downward force due to gravity, thereby increasing the surface pressure.

Thus, in the scenario where more air is added, both the density of the air and the surface pressure increase, establishing a direct relationship between these two factors.