What instrument is used to measure air pressure?

• A. Barometer
• B. Hygrometer
• C. Thermometer
• D. Anemometer

Answer: (A)

Measuring air pressure is done with a barometer. A barometer detects the weight of the air pressing down on the surface, so when atmospheric pressure is high the reading goes up, and when it’s low the reading goes down. Mercury barometers use a column of mercury that moves with the pressure, while aneroid barometers use a small sealed chamber that flexes in response to pressure changes and displays the value on a dial.

Hygrometers measure humidity, the amount of water vapor in the air. Thermometers gauge temperature, how hot or cold the air is. Anemometers measure wind speed, how fast air is moving.