How is atmospheric pressure defined?

Atmospheric pressure is defined as the total weight of the gaseous mass at any given place and time. This definition captures the essence of how atmospheric pressure is generated by the weight of air above a specific point. The atmosphere is made up of various gases, primarily nitrogen and oxygen, and each gas contributes to the total weight of the air column above the location being measured.

This weight acts on a surface area, creating pressure, which is typically measured in units such as pascals or atmospheres. Atmospheric pressure decreases with altitude because there is less air above the measurement point. Weather and climatic conditions also play a significant role, as humidity and temperature can affect the density and composition of the air, thereby influencing pressure readings.

Other choices provided do not accurately reflect the definition of atmospheric pressure. The total weight of water vapor pertains only to the moisture content in the air, which is just one component and not representative of the entire atmospheric pressure. The pressure exerted by the Earth's crust and the pressure in a closed container pertain to different physical concepts unrelated to atmospheric pressure as defined by the gaseous mass in the atmosphere.