What instrument records atmospheric pressure?

A barometer records atmospheric pressure.

Italian scientist Evangelista Torricelli invented the mercury barometer in 1643. His instrument used a column of mercury supported by air pressure, demonstrating that the atmosphere has weight. The height of the mercury column changes as atmospheric pressure rises or falls.

Modern barometers commonly use an aneroid capsule, a small sealed metal chamber that flexes as outside pressure changes. Electronic barometers use pressure sensors and can feed measurements to weather stations, aircraft systems, and smartphones.

Meteorologists use pressure patterns to identify weather systems. Falling pressure often accompanies an approaching low-pressure system, while rising pressure commonly follows improving weather, although pressure alone cannot predict every local condition. Standard sea-level pressure is 1013.25 hectopascals, or 1013.25 millibars.