The instrument used for measuring atmospheric pressure is known as

The instrument used for measuring atmospheric pressure is called a barometer. Atmospheric pressure is the force exerted by the weight of the air on the Earth's surface. A barometer measures this pressure and is typically composed of a long glass tube that is closed at one end and open at the other end. The closed end of the tube is then placed in a container of mercury, which is a heavy liquid metal that is sensitive to changes in air pressure. As the air pressure increases, the weight of the air pushes down on the surface of the mercury, causing it to rise up the tube. Conversely, as the air pressure decreases, the weight of the air on the surface of the mercury decreases, causing the level of mercury in the tube to drop. The height of the mercury column in the tube is then used to measure the atmospheric pressure, with higher columns indicating higher pressures and lower columns indicating lower pressures. Therefore, a barometer is the instrument used for measuring atmospheric pressure.