Barometer

Barometr, Skwer Bowiena, Sopot - panoramio

NSRW Siphon diagram

Gasparo Berti Experiment

Evangelista Torricelli by Lorenzo Lippi (circa 1647, Galleria Silvano Lodi & Due)

Torricelli

Barometer is an instrument used to measure atmospheric pressure. It plays a crucial role in meteorology, the science that studies the atmosphere and its phenomena, especially with respect to weather and weather forecasting. The concept of the barometer was first developed in the 17th century, and since then, it has undergone significant advancements, leading to various types of barometers being used today.

History

The invention of the barometer is credited to the Italian scientist Evangelista Torricelli in 1643. Torricelli, a student of Galileo Galilei, demonstrated that air has weight by using a tube filled with mercury. He inverted the tube into a dish of mercury and observed that the mercury level dropped, leaving a vacuum at the top. This experiment led to the creation of the first mercury barometer and proved the existence of atmospheric pressure.

Types of Barometers

There are primarily two types of barometers: mercury and aneroid.

Mercury Barometers

A Mercury barometer consists of a glass tube that is closed at one end and open at the other, filled with mercury. The open end is submerged in a mercury reservoir. The height of the mercury column in the tube changes as the atmospheric pressure varies, with higher pressure pushing more mercury up the tube and lower pressure allowing it to drop. Mercury barometers are known for their accuracy and were widely used until concerns about mercury's toxicity led to the development of safer alternatives.

Aneroid Barometers

Aneroid barometers, invented by Lucien Vidie in 1843, do not use mercury. Instead, they contain a small, flexible metal box called an aneroid cell. Changes in atmospheric pressure cause the cell to expand or contract. This movement is magnified by a mechanism and displayed on a dial, making it easier to read. Aneroid barometers are safer and more portable than mercury barometers but can be less accurate unless regularly calibrated.

Applications

Barometers have a wide range of applications, from meteorology to aviation. In meteorology, they are used to measure atmospheric pressure, which helps in forecasting weather and identifying changes in weather patterns. A sudden drop in atmospheric pressure, for example, can indicate the approach of a storm. In aviation, barometers are used to determine altitude, as atmospheric pressure decreases with an increase in altitude.

Digital Barometers

With advancements in technology, digital barometers have become common. These instruments use electronic sensors to measure atmospheric pressure and often include features such as temperature and humidity sensors, making them versatile tools for weather observation and forecasting.

Conclusion

The barometer is a vital instrument in understanding and predicting weather. From its historical mercury-based design to modern digital versions, it has evolved significantly over the centuries. Despite the development of new technologies, the basic principle discovered by Torricelli remains at the heart of how barometers function, demonstrating the enduring importance of this tool in meteorology and beyond.