kviksølvbarometren

A kviksølvbarometer is a type of barometer that uses mercury to measure atmospheric pressure. Invented by Evangelista Torricelli in 1643, it was the first practical instrument for measuring air pressure. The device consists of a glass tube closed at one end, filled with mercury, and then inverted into a dish containing more mercury. The weight of the atmosphere presses down on the mercury in the dish, and this pressure supports a column of mercury in the tube. The height of this mercury column is directly proportional to the atmospheric pressure.

The standard unit of pressure measured by a mercury barometer is millimeters of mercury (mmHg), also known as Torr. A standard atmospheric pressure at sea level is approximately 760 mmHg. Changes in the height of the mercury column indicate variations in atmospheric pressure. A rising column suggests increasing pressure, often associated with fair weather, while a falling column indicates decreasing pressure, typically heralding unsettled weather.

Despite their historical significance and accuracy, mercury barometers have largely been replaced by more modern and safer instruments, such as aneroid barometers, due to the toxicity of mercury. However, they are still used in some scientific applications and for calibration purposes. The principle behind the mercury barometer, however, remains fundamental to understanding atmospheric pressure measurements.