A measurement of the pressure exerted by Earth's atmosphere at a given point.

• A. Humidity
• B. Barometric pressure
• C. Wind
• D. Temperature

Answer: (B)

Atmospheric pressure is the force the air above us exerts on surfaces per unit area. The measurement of that pressure at a specific location is called barometric pressure. Barometers, which can use mercury or aneroid sensors, quantify this pressure and are read in units like hectopascals or kilopascals. At sea level the standard pressure is about 1013 hPa, and pressure decreases with altitude or changes with weather systems. Humidity measures how much water vapor is in the air, not the weight of the air itself. Wind describes the movement of air caused by pressure differences, not the static pressure at a point. Temperature influences pressure through the gas laws, affecting density and pressure indirectly, but it is not the measurement of atmospheric pressure.