What instrument is typically used to measure atmospheric pressure?

The instrument that is typically used to measure atmospheric pressure is a barometer. A barometer functions by utilizing the weight of the air above it to create a measurable force. This is often done with a column of liquid, typically mercury or aneroid mechanisms, where changes in external atmospheric pressure cause the liquid to rise or fall in a tube.

Understanding this concept is essential in meteorology, as atmospheric pressure can influence weather patterns. For example, high-pressure areas tend to be associated with clear, calm weather, while low-pressure areas can lead to clouds and precipitation.

Other instruments mentioned have different purposes: a thermometer measures temperature, a hydrometer gauges the density of liquids, and an altimeter measures altitude by determining the atmospheric pressure, but it is not primarily designed for measuring atmospheric pressure in isolation.