Barometer is an device in the study of meteorology. It is used to study atmosphere and weather phenomena. A Barometer is a scientific tool used to measure the atmospheric pressure at a specific temperature.

In this article, we will learn about barometers and their related terms including types, working principles, uses, and many more related topics.

What is a Barometer?

A barometer is a scientific device that indicates air pressure. It is used for monitoring atmospheric pressure, commonly used for weather forecasting and altitude calculations. It varies with altitude either above or below sea level. In 1643, the Italian scientist E. Torricelli discovered a scientific device named barometer. In the vacuum of barometer, mercury is used. The basic principle of a barometer relies on the balance between the weight of the air in the atmosphere and the force exerted by a column of mercury or other liquid in a vertical tube.

History of Barometer

Evangelista Torricelli, an Italian physicist and mathematician, invented the barometer for the first time in 1643. Torricelli was concerned by the problem of water pumps, that lifted water to a height of about 32 feet only. He assumed that the weight of the atmosphere was responsible for this problem.

To solve the problem, Torricelli took a large glass tube (one side open) filled with mercury, and put the opened side into a container of mercury. Surprisingly, the mercury did not completely flow out from the tube, even it stood at a height of about 30 inches. Torricelli understood that the weight of the mercury line in the tube was balanced by the weight of the atmosphere pressing down on the mercury in the container.

Torricelli’s experiment proven the existence of atmospheric pressure and also he was finding the way of measuring it. This mercury barometer, which was also called as a Torricellian tube, became the standard instrument for measuring atmospheric pressure for centuries.

How does a Barometer work?

Barometer is a glass tube that has one side open and the other side is closed. The open side of a barometer is placed in a mercury filled basin and the closed-end side is at the top. Instead of water, we normally use mercury for barometer. Because the density of mercury is more than water. The working process of a barometer is based on the balancing of mercury weight with respect to the atmospheric pressure. When the atmospheric pressure decreases, the mercury level also decreases and when the atmospheric pressure increases, the mercury level also increases. Rising the level of mercury of a barometer indicates improving weather and falling level of mercury indicates worsening weather. When the mercury level suddenly fall down, it indicates storming weather. The rising and falling level of mercury are calculated using a scale marked on the glass tube.

Types of Barometer

There are two types of barometer namely

• Mercury Barometer
• Aneroid Barometer

Mercury Barometer

The most popular barometer is the mercury barometer. Italian scientist Torricelli invented mercury barometer in 1643. It consists of a mercury-filled glass tube column and for measuring the readings, it will markings with inches on it. The top of the glass is closed and the bottom of the glass is opened and placed in a mercury-filled basin, or cistern. These barometers are gravity and environment-corrected to get accurate reading. For the reason, the more denser metal named mercury is used.

Aneroid Barometer

Aneroid barometer is made up of a combination of aneroid capsule, a thin and flexible metal box made of an alloy. This metal box is the alloy of beryllium and copper. For greater expansion and contraction of levers and springs of the box, the metal box is tightly sealed. This will happen due to a change in atmospheric pressure outside the box.

Difference between Barometer and Manometer

The basic differences between barometer and manometer are as follows: