What is a Barometer?
A barometer measures atmospheric pressure. The air in the atmosphere exerts a force called pressure that constantly changes due to moving weather systems. Therefore, in conjunction with other meteorological instruments, a barometer helps to predict clear or rainy weather. In 1643, Evangelista Torricelli invented the first barometer. He figured that if he had a vacuum, an airless space, he could compare the ever-present atmospheric pressure with zero pressure. So he placed a vacuum contained in a glass tube on top of a larger container of mercury. The air presses down on the mercury’s exposed surface and pushes it up into the tube. The higher the mercury level, the greater the air pressure. Originally, the units of air pressure were just millimeters of mercury. People could finally measure the force of air. Since the advent of “Torricelli’s tube,” others developed the aneroid barometer that works without liquid. In this instrument, a flexible metal accordion box that resembles a bellows
Meteorologists use barometers to measure atmospheric pressure to determine how the weather is changing. Read on to learn more about a forecaster’s greatest friend… Barometer History The barometer dates back to 1643, when Italian scientist Evangelista Torricelli used a 34-foot tube filled with water to measure air pressure. As weather patterns shift, the “weight” on the water changes, which causes the column to move up or down. Perfecting the design, Torricelli replaced water with mercury, which allowed the use of a much smaller tube. While water used a 34-foot tube, mercury accurately recorded pressure in a 3-foot tube.
