Mercury Barometer

A mercury barometer is a scientific instrument used to measure atmospheric pressure. It consists of a glass tube filled with mercury, inverted into a container of the same liquid. The weight of the mercury creates a vacuum at the top, and the atmospheric pressure pushes down on the mercury in the container. The height of the mercury column in the tube indicates the air pressure: higher mercury levels mean lower pressure, while lower levels indicate higher pressure. This tool is essential in weather forecasting, as changes in atmospheric pressure can signal different weather conditions.