What instrument is used to measure atmospheric pressure?

The instrument used to measure atmospheric pressure is a barometer. Barometers work based on the principle that atmospheric pressure can be quantified by observing the height of a column of mercury or any other fluid within a sealed tube. As atmospheric pressure increases or decreases, it exerts a force on the liquid in the tube, causing it to rise or fall. This change in height can be calibrated to provide a precise measurement of pressure, typically expressed in millibars or inches of mercury.

Understanding atmospheric pressure is crucial for weather forecasting as it influences weather patterns and conditions. For example, high-pressure systems are generally associated with clear skies, while low-pressure systems can lead to clouds and precipitation. This importance underscores why a barometer is essential in meteorology and aviation.

In contrast, other instruments like thermometers measure temperature, anemometers are designed to measure wind speed, and hygrometers are used to assess humidity levels. Each of these instruments serves a specific purpose and does not provide information about atmospheric pressure.