Barometerets

A barometeret is a scientific instrument used to measure atmospheric pressure, which is the force exerted by the weight of the air above a given point. The term originates from the Greek words *baros* (weight) and *metron* (measure), reflecting its primary function. Barometers are essential tools in meteorology, aviation, and various scientific disciplines for predicting weather changes, monitoring altitude, and studying atmospheric conditions.

The most common type of barometer is the mercury barometer, invented by Evangelista Torricelli in 1643. It consists of a glass tube filled with mercury, inverted into a reservoir of the same liquid. Changes in atmospheric pressure cause the mercury level inside the tube to rise or fall, allowing precise measurements. Aneroid barometers, introduced later, use a small, flexible metal box (aneroid cell) that expands or contracts with pressure changes, eliminating the need for liquids. These are more portable and widely used in everyday applications.

Barometers are calibrated in units such as hectopascals (hPa), millibars (mb), or inches of mercury (inHg). A standard atmospheric pressure at sea level is approximately 1013.25 hPa or 29.92 inHg. Fluctuations in pressure often correlate with weather patterns—falling pressure may indicate an approaching storm, while rising pressure suggests clearer skies.

Beyond meteorology, barometers play a role in aviation for determining altitude and in industrial settings for monitoring environmental conditions. Modern digital barometers integrate with weather stations and smartphones, providing real-time data for personal and professional use. Their accuracy and reliability have made them a cornerstone of atmospheric science for centuries.