Elavhõbedabaromeetrid

Elavhõbedabaromeetrid, also known as mercury barometers, are instruments used to measure atmospheric pressure. They work on the principle that the weight of the atmosphere pressing down on a surface of mercury in a dish is balanced by the weight of a column of mercury in an inverted tube. The height of this mercury column is directly proportional to the atmospheric pressure.

The first mercury barometer was invented by Evangelista Torricelli in 1643. His design involved filling a glass tube, sealed at one end, with mercury and then inverting it into a dish also containing mercury. As the mercury in the tube descended, it created a vacuum at the top, and the atmospheric pressure then pushed the mercury up into the tube until the weight of the mercury column equaled the atmospheric pressure.

The height of the mercury column is typically measured in millimeters of mercury (mmHg) or inches of mercury (inHg). Standard atmospheric pressure at sea level is defined as 760 mmHg or 29.92 inHg. These instruments were crucial for weather forecasting, navigation, and scientific research for centuries.

While highly accurate, mercury barometers pose health and environmental risks due to the toxicity of mercury. Modern weather stations and scientific institutions now predominantly use aneroid barometers, which are mechanical devices that do not contain mercury, or digital barometers that rely on electronic sensors. However, mercury barometers are still sometimes used in specialized scientific applications or for educational demonstrations.