Which instrument is specifically designed to measure barometric pressure?

An aneroid barometer is specifically designed to measure barometric pressure by utilizing a small, sealed metal box that expands or contracts with changes in atmospheric pressure. This mechanical movement is translated into a reading on a dial or scale, allowing for the direct measurement of air pressure without the use of liquid.

The mercury barometer, although also an instrument that measures barometric pressure, functions differently, relying on a column of mercury in a glass tube to indicate pressure changes. While it accurately measures atmospheric pressure, it is primarily an older method and less commonly used today compared to the aneroid barometer.

A hygrometer measures humidity rather than barometric pressure. It assesses the amount of moisture in the air, which is a different meteorological parameter entirely. The psychrometer is akin to a hygrometer as it also measures humidity, typically using the principle of wet and dry bulb temperatures. Both hygrometers and psychrometers do not provide barometric pressure readings, reinforcing that the aneroid barometer is the correct choice for measuring atmospheric pressure specifically.