How is atmospheric pressure defined?

Atmospheric pressure is defined as the pressure exerted by the weight of air on the surface of the Earth. This pressure results from the gravitational force acting on the molecules in the atmosphere, causing them to exert a force on areas below them. At sea level, atmospheric pressure is typically around 101.3 kPa (kilopascals) or 14.7 psi (pounds per square inch), which provides a standard reference point for various applications in science and engineering, including gas systems.

Understanding this concept is essential for working within the context of gas systems, as atmospheric pressure affects how gases behave and their measurements. For example, when dealing with gas lines, an understanding of atmospheric pressure helps in recognizing how it influences gas flow and burner operations. Any variations in atmospheric pressure can impact the efficiency and safety of gas appliances and systems, which is why this foundational knowledge is critical for professionals in the field.

The other options do not accurately define atmospheric pressure. The pressure exerted by water vapor relates specifically to humidity levels rather than the total atmospheric pressure. The pressure inside a gas line at sea level refers to a specific system condition and not the general atmospheric pressure surrounding us. Finally, the pressure of a gas in a closed container pertains to gas