How does atmospheric pressure change with elevation?

Atmospheric pressure decreases with increasing elevation due to the thinning of the air as you move higher in the atmosphere. Specifically, the decrease in atmospheric pressure is approximately 0.5 psi for every 1000 feet of elevation gain. This phenomenon occurs because the weight of the air above a given point is reduced as you ascend, resulting in lower pressure.

Understanding this concept is essential for fire service pump operators because it affects how pumps operate and how water behaves under different atmospheric conditions. For example, lower atmospheric pressure can impact the ability of a pump to draw water, especially in higher elevation areas where the atmospheric pressure is significantly lower. Consequently, recognizing how pressure changes with elevation is crucial for effective pump operation and water delivery during fire service operations.