Everything You Need to Know About Barometer

What makes predicting the weather so easy? How can a person like you and I know if it is going to rain or if it is going to be sunny?


Prediction of weather has become quite common in this era of technological boost. We get this information from weather apps or the weather segments of news channels, and they come to know about such meticulous information through the readings of unnumbered instruments. One of them being a Barometers which conveniently tells the user what kind of weather will prevail today and if it is going to rain, precisely when.

Due to its invention, we cannot only come to know about the change of weather through the news. We can also predict the weather on our own through personal barometers that have emerged as a popular instrument for several professional and amateur people. Let’s understand what Barometer is and how it can forecast weather with such precision and accuracy.

What is Barometer?

A Barometer is a scientific device that is used to measure the atmospheric pressure of a region. The atmospheric pressure is different in different regions and altitudes, and the barometer helps in measuring it. Whereas air temperature is measured using a humidity monitor as seen on theweathermakers.org

The air pressure is highest at the sea level, and as you go higher, it lowers gradually. The air pressure of a region never remains stagnant, and it is ever-changing. It is due to the rotation and revolution of the Earth that the air pressure keeps changing.

It helps determine the weather conditions of an area and forecasting how they are likely to change and when. It gave weather forecasting a scientific backing and revolutionized the practice. 

Uses of Barometer

Use 1

Measures Atmospheric Pressure 

Use 2

Widely used for Weather Forecasting

Use 3

Used to Measure the Tyre's Pressure in Aircraft.

Use 4

Application in Fluid Mechanics, Astronomy, Physics & Chemistry

History of Barometer

It was invented by Evangelista Torricelli in 1643, although some people also hold Gasparo Berti in high esteem who built the first water barometer, applying the same principle of functionality. The first barometer was in Florence, Italy, around 1644 by Torricelli, and now almost five centuries down the line; it is still widely used owing to its modern usefulness and application.

Amongst an array of modern uses, its prime use has been seen in the weather forecast process. How did Torricelli come to invent the Barometer? During his time, it was widely believed that air had no weight. Torricelli held the contradictory idea. He made this belief the basis of his experimentation as the mercury-filled in glass tubes. He proved his little idea by observing that the mercury might fall away from the closed end of the tube until it is on the level where the air and the weight of mercury are balanced.

The theory of Torricelli, though had foundations of a barometer, was still incomplete. This was consummated by the French scientist Blaise Pascal. He proved how air pressure is a consequence of the vertical weight of the air. In 1646, he did an experiment through an acquaintance as he asked him to take the mercury-filled barometer to a high altitude. He expected the mercury levels to fall down, and sure enough, that is exactly what happened. 

This proved his theory of the vertical weight of air, causing a change in air pressure. This is why pressure is high in high altitudes such as in mountainous regions and high pressure near the surface of the Earth. Also, it is the reason why astronauts require large oxygen cylinders as the air pressure in the space is nearly non-existent. The air pressure of the Earth is one of the reasons why this planet is habitable.

The airplanes now use altimeters to determine the altitude at which they are flying, previously used barometers for the same function. The change is the atmospheric pressure shown by the barometer told the pilots at which altitude they are flying.

Benefit 1

Barometers are essentially helpful to predict the weather conditions of a vast area, and particularly helpful for meteorologists. But the advancement of technology, personal barometers have become quite a common thing.

Benefit 2

It is something largely used by sailors, hikers, campers, mountaineers, fishers who need to keep a tab on the change of weather for their activities to be conveniently carried out. It helps in warning a sailor.

Benefit 3

It has become quite a sight in the regular household as well, to know whether it is going to rain or not to take an umbrella with you. It can give you precise readings about the atmospheric pressure on command.

Working of Barometer

The traditional Barometer, which was widely is used in its time, is the Mercury barometer. Thus, conventionally, the substance that is used for the measurement of the atmospheric pressure via Barometer is mercury. A 3-feet high glass tube is filled with mercury with one end open and one end closed, sort of like a thin cylindrical container. The glass tube is settled inside another, larger container, which also contains some quantity of mercury. This home of the glass tube is known as the reservoir. 

The weight of the mercury inside the glass tube is balanced with the ambient atmospheric pressure, which is how the Barometer performs its primary function as I have mentioned that the basic principle of the functionality of the barometer involves the measurement of the air that is being pressed down towards the object on the surface, much like that the air pressure above the reservoir is pressed down and the weight of the mercury changes till the weight of both the air pressure above the reservoir and the weight of the mercury itself is the same. 

Subsequently, the set of scales incorporated in the system takes the readings and renders the exact figure of the atmospheric pressure. There is an inverse relationship between the weight of the mercury and the atmospheric pressure. If the weight of mercury less than the air pressure, the mercury will rise, signaling high pressure. Similarly, if the weight of mercury is higher than that of the air pressure, it will soar signaling low pressure. 

In today’s date, innumerable kinds of Barometers have come into existence by keeping pretty much the same principle in mind and yet with some distinctions. Mercury Barometers are not a common sight these days, although it is the traditional mechanism of measuring the air pressure of a region. This is also considering the fact that mercury is a highly toxic liquid metal, and all the instruments are formerly used it (including clinical thermometer), they are widely discarded and replaced with much safer means.

With new developments, several new, more convenient, and safer ways have been introduced to perform the same function and much more. Let’s understand the basic kinds of barometers used today, how they are different from each other, and how do each of them measures the air pressure.

Types of Barometer

Aneroid Barometer

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  • Aneroid Barometers that were invented by the French scientists Lucien Vidi in the year 1844. It is prime replacements of Mercury barometers owing to the fact that the former one is much safer than the latter, considering that mercury is a highly toxic substance.
  • The readings are shown through a needle movement that moves as per the movement of some levers. The dial of the device shows the precise air pressure. Thus, the design of the aneroid resembles a compass. These are typically used as home accessories.

Digital Barometer

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  • Digital Barometers are the ones that are widely being used today, especially by people who often find themselves in regions of fluctuating air pressures such as mountaineers, trekkers, sailors, etc.
  • The atmospheric pressure that they measure also helps determine the humidity levels of a region, so its use has become multi-fold in all this time. The measurement of the speed and the direction of the wind is also not an uncommon sight in the modern digital barometer these days.


Undoubtedly, the invention of the barometer has revolutionized our ways, and with the introduction of different types of barometers has ensured that all kinds of people have an ideal model for them. Applying the same underlying principle, the operation of all the kinds of the barometer is carried out, the only difference is in their design and mode of function.

Though a popular thing in its time, Mercury barometer has become nearly obsolete due to the introduction of much safer ways of measuring the atmospheric pressure. It is the digital barometer that has emerged as the 21st-century people’s choice with the aptitude of measuring all weather elements virtually.