Barometer tubes, Nairobi Industrial Area

A barometer tube is a long, sealed glass or metal tube used to measure atmospheric pressure. It is typically filled with a liquid, such as mercury, with one end sealed and the other submerged in a reservoir of the same liquid. The atmospheric pressure pushes on the reservoir, causing the liquid level in the tube to rise or fall. The height of the liquid column reflects the current atmospheric pressure, allowing for precise readings. Barometer tubes are commonly used in meteorology, physics, and laboratory experiments to observe pressure changes and calibrate instruments.