What term describes the atmospheric pressure at sea level, typically about 100 kPa and varying with altitude and weather?

• A. Atmospheric Pressure
• B. Gauge Pressure
• C. Absolute Pressure
• D. Pressure Differential

Answer: (A)

Atmospheric pressure is the pressure exerted by the air surrounding us. At sea level it’s about 100 kPa and it changes with altitude and weather patterns, which is why you often hear it referred to as barometric pressure. This is the baseline pressure for the environment.

Gauge pressure measures how much the pressure rises above ambient atmospheric pressure, so it’s the difference between absolute pressure and atmospheric pressure. Absolute pressure is the total pressure relative to a vacuum, so it’s the sum of atmospheric pressure and any gauge pressure. Pressure differential is just a general term for the difference between two pressures, not the specific sea-level atmospheric value.