A barometer is a device for measuring atmospheric pressure. In hygienic research, the most common metal barometers are aneroids and liquid barometers - mercury.

IN aneroid barometer fluctuations in atmospheric pressure are perceived by a round metal box with wavy walls (aneroid box), from which it is removed (Fig.). The elastic walls of the box bend when the pressure increases, and bulge when the pressure decreases. The walls of the box are connected by a gear system to the instrument pointer. The latter indicates on the instrument scale, graduated in millimeters of mercury, the value of atmospheric pressure.

Mercury barometer is a U-shaped curved glass tube containing; atmospheric pressure is determined by the difference in mercury levels in the long and short sections of the tube.

To continuously monitor changes in atmospheric pressure, self-recording devices - barographs - are used. Fluctuations in atmospheric pressure are recorded on a tape placed on a rotating drum.

Atmospheric pressure is usually measured in millimeters of mercury (mmHg) and millibars (mbar). 1 mbar = 0.75 mm Hg. Art., 1 mm Hg. Art. = 1.33 mbar.

Barometer (from the Greek baros - heaviness and metreo - I measure) is a device for measuring atmospheric pressure. In meteorological and hygienic practice, mercury barometers are most widely used. There are three systems of mercury barometers (Fig. 1): cup (1), siphon (2) and siphon-cup (3).

Rice. 1. Mercury barometer systems. H is the height of the mercury column corresponding to atmospheric pressure.

Currently, only cup and siphon-cup barometers are used. In stationary cup barometers with a compensated scale, atmospheric pressure is determined directly from the position of the mercury in a glass tube (using a scale marked on metal frame barometer). In expeditionary cup barometers, before observation, the mercury level in the cup is first set at the zero point using a special screw (at the bottom of the device). In siphon-cup barometers, the value of atmospheric pressure is measured by the difference in the heights of the mercury column in the long (sealed) and short (open) legs. The barometer allows you to make readings with an accuracy of 0.05 mm Hg. Art. Using the screw on which the leather bottom of the barometer cup rests, the mercury level in the short (open) elbow is brought to the zero point, and then the barometer readings are taken. To determine tenths of a millimeter of mercury (in hygienic practice this happens relatively rarely), a movable metal vernier scale is used. The found numerical expressions of atmospheric pressure must be brought to 0° using calculations using a special table. Temperature corrections to the barometer reading can be quite significant. Barometers are installed away from sources of thermal radiation (stoves, heating devices, sun), as well as from doors and windows.

A metal aneroid barometer is very convenient for observation, especially in expeditionary conditions (Fig. 2). It is less accurate than the mercury barometer by which it is usually calibrated. A metal Bourdon tube, bent in the shape of a horseshoe, or more often a metal pad with corrugated walls, from which air has been removed, changes its volume and deforms with changes in pressure. This deformation is transmitted using a system of levers to a pointer, which indicates the amount of atmospheric pressure on the scale.

Rice. 2. Mechanism of the aneroid barometer (diagram): 1 - aneroid box; 2 - spring; 3 - rod; 4 - crank lever; 5 - arrow axis; 6 - arrow; 7 - hinge chain; 8 - spiral spring; 9 - scale.

Currently, atmospheric pressure is more commonly expressed in international units - millibars (mb). 1 mb is equal to 0.75006 mmHg. Art., and 1 mm Hg. Art. corresponds to 1.3332 MB. There are special tables for converting millimeters of mercury into millibars.

Barograph is a self-recording barometer for continuous recording of atmospheric pressure. In hygienic practice, only aneroid barographs are used (Fig. 3). The principle of their operation is based on the deformation under the influence of changes in atmospheric pressure of a package of 5-7 aneroid boxes connected together; this deformation is transmitted by a system of levers to the recorder pen. As atmospheric pressure increases, the aneroid boxes compress and the lever with the feather rises; when the pressure decreases, the boxes expand under the action of the springs placed inside them and the pen draws a line downwards. The pressure record is drawn with the instrument's pen on a special paper tape, graduated in millimeters of mercury or millibars, placed on a rotating barograph drum. There are barographs with daily and weekly winding. To eliminate temperature effects on barograph readings, bimetallic capacitors are inserted into them. Barographs are installed away from heating devices and protected from direct exposure to sunlight.

Rice. 3. Barograph mechanism (diagram): 1 - recorder lever; 2 - column of aneroid boxes; 3-5 - system of rods and levers.

The Earth's atmosphere, which extends several hundred kilometers upward, presses on the surface of our planet. It is this pressure that is called atmospheric. To measure it, a device called a barometer was invented. The creator of the device was the Italian Evangelista Torricelli, who lived in the 17th century. It was he who explained to people why a barometer was needed.

Atmospheric pressure usually “jumps” due to changes in weather conditions: it drops before bad weather, and rises in good weather. Meteorologists record any pressure fluctuations on the map and determine the movement of cyclones and wind directions. Lines of equal pressure are called isobars from the Greek baros (gravity) and isos (equal).

Types of barometers

There are two types of barometers - aneroid and mercury. The second is much more accurate and reliable, the first is more compact and convenient, and can be pocket-sized if necessary.

A mercury barometer shows pressure by the height of a mercury column, next to which a measuring scale is attached. Usually it is an 80 cm glass tube filled with mercury, which is sealed at one end and open at the other and immersed in a cup of mercury. There is no air in the tube, so the space at the top is called a Torricelli void. There is no liquid in the aneroid. It shows the pressure that acts on a corrugated metal box with thin walls, inside of which a vacuum has been created. When atmospheric pressure decreases, the box expands slightly; when it increases, it contracts, and the pressure itself acts on a special attached spring. Typically, several aneroid boxes are used, which are connected in series. Using a lever transmission system, the needle rotates and moves along a circular scale graduated according to the mercury barometer. It may contain the following inscriptions: “variable”, “rain”, “very dry”, “clear”.

It is aneroids that are used on airplanes, ships, and also at meteorological stations. Typically, a stylus is attached to the hands and it automatically records readings.

What pressure is normal

The fact is that there is no standard definition of normal atmospheric pressure. Depending on the geographical location of the region, the norm that the barometer shows is different. So, for example, in St. Petersburg, which is located at the altitude closest to sea level, it is 760 mmHg. But in Moscow, located on a hill, - 748 mmHg.

Only the local hydrometeorological service can tell you exactly what is the norm for a particular city.

Now you know what a barometer is. Good luck with your discoveries!

A device for measuring air pressure at home is necessary for all people, especially those in the category that is dependent on changes in this parameter: for example, hypertensive patients with old injuries and open wounds, heart patients also feel unstable when there is a sudden change in weather. Our industry and foreign manufacturers have been producing unique instruments and devices for a long time, so choosing a beautiful and high-quality barometer for your home today is not a problem.

In addition to pressure, these devices show temperature, humidity, forecast precipitation for the near future, and also warn of increased wind. Those readers who are still unfamiliar with such a useful home weather forecaster are strongly advised to read our article to fill in the gaps in their horizons.

We all know from school curriculum that around our planet there are quite dense layers of the atmosphere, the thickness of which is several tens of kilometers. The mixture of various gases that make up its basis, although light in weight, exerts a certain pressure on the surface of the earth.

IN Everyday life we don’t feel it, because our body is perfectly adapted to it, but the magnitude of this pressure needs to be known. For normal weather conditions, it has the following value - 760 millimeters of mercury (mm Hg), this is the parameter shown by working home barometers. Previously, mercury was used for accurate measurements, but its vapors are dangerous to humans, so it was replaced with other liquids.

A household aneroid barometer operates without liquid, and the pressure in it is measured using a sealed box made of thin tin, but before that, some of the air has been pumped out of it. We will talk in detail about the design and device in the next section.

As a rule, each barometer can show several physical quantities; home weather stations are produced with the function of several devices at once: a thermometer that very accurately shows the real temperature in the apartment or a hygrometer that indicates the humidity inside the room. The smart device notifies about possible precipitation, increased wind and approaching storm.

Device

As we have already said, there is no flask with liquid inside the aneroid, but a tin box whose walls compress or expand. A spring is attached to it, which rotates the needle of the device, and on a scale mounted on the dial, you can monitor the change in pressure in real time. For accurate measurements, engineers use up to 10 aneroid boxes connected in parallel into one circuit, resulting in the most accurate barometer.

On a semicircular or circular scale, depending on the modification of the device, there are several specific zones:

• dry;
• variable;
• It's clear;
• rain;
• storm.

When the pressure decreases, you can be completely sure that the weather is getting worse and it is better not to go on a picnic, but if the arrow moves in the direction of increase, this means that it will be sunny and you can go to barbecue.

The barometer is very helpful for avid fishermen, because the fish feel the change in pressure quite strongly and stop biting at low pressure values. To monitor changes in parameters, it is enough to place the control arrow on top of the main one, and then the changes will show the result - the pressure increases or decreases.

What types of barometers are there?

These products are not very diverse - there are four main types, we will tell you in detail about each:

1. The mercury barometer was invented in the mid-17th century by the Italian physicist Evangelista Torricelli, who was a student of Galileo, and after his death became his successor at the department of the University of Florence. Two years after the death of his teacher in 1644, he proved the possibility of obtaining emptiness, later named Torricelli after his name, and invented the mercury barometer. Of course, that primitive design with mercury poured into a plate was not widely used, although it was very accurate. It has been proven that mercury vapor has a negative effect on the human body, but the principle of operation is still used in special barometers at standard meteorological stations different countries to ensure precise weather control.
2. Liquid analogues are currently practically not used, because they have a rather large error and monitoring weather changes with their help will be problematic. A column of liquid does not behave identically at different temperatures, so large errors arise, and meteorologists only need accurate results. The most famous modification of a liquid barometer is a product with a flask filled with colored glycerin. It expands less from high temperatures and has a very attractive decorative effect.
3. The most popular today is the mechanical barometer because it is much more compact than the first two options and has great accuracy. Their main merit is that they are absolutely safe to use, although they are quite complex to manufacture. The outer case of the barometer, which is placed on the wall, looks like a classic antique clock with a round dial. In retail sales you can find simple desktop products with a rectangular body made of durable plastic. We have already described the principle of operation, so we will not repeat it, we will only note that such devices are produced compact - the so-called pocket version, a little larger in size - this is a desktop one, and then there are wall-mounted devices, in which the body is made of polished acrylic or high-quality wood. Sometimes manufacturers produce a home weather station, where a barometer, thermometer and hygrometer are built into one case made of polished wood.
4. The fourth type is an electronic barometer; it is a very high-precision and compact instrument. The main element is the same sealed box with thin tin walls, which react very sensitively to the slightest change in external pressure, but readings are taken by sensitive sensors. The design necessarily contains a microprocessor with an electronic unit, which outputs the processed data to a digital liquid crystal display. Such a device works simultaneously as a watch and a compass to determine its location if necessary; the case can be waterproof, so such devices are often used by tourists, geologists in search parties, as well as avid hunters and fishermen.

We have talked in detail about the main types that exist in the world of barometers, now let’s talk about what you need to know to choose best option for use at home.

Criterias of choice

First of all, we need to decide what we are choosing - a barometer with a minimum set of functions or a miniature home weather station with readings of pressure, temperature, humidity and a warning about the wind increasing to stormy. If you need original gift for a man, a barometer is an excellent option, because the stronger sex likes different instruments.

Housing material

There are quite a few options here, because the body of a modern wall barometer can be made of polished acrylic, plastic, wood of different types from simple to elite. The shape is also varied: round, rectangular, elongated vertically or horizontally, in the form of a steering wheel, anchor or mooring bollard - a bollard for securing mooring ends, such a product would be appropriate on the table of a retired sea captain.

Fastening

The gift can be placed on the wall, for example, a barometer stylized as a steering wheel will look great in a house on the seashore and remind the owner of his turbulent youth, when a young sea wolf roamed the expanses of the world's oceans. An anchor made of brass or golden metal, located in the office of a business man, will personify reliability, stability and confidence.

A stand for an expensive fountain pen in the form of a small barometer looks great on the desk of the head of a small office and notifies visitors that the owner of the office is always aware of all events, and not only knows what the weather will be like tomorrow.

Dimensions

It's easier to navigate here:

• if you are purchasing a barometer for your home, then you need to choose standard sizes so that the product looks normal on the wall and does not stand out like a black sheep;
• as a gift, you need to choose something that is not small-sized, but not the size of an average closet; the most acceptable option is a width of 120 mm, a height of up to 450 mm and a depth of 30-40 mm.

Tabletop options are even more miniature.

Clock face

If this is a standard barometer, then all the scales should be perfectly readable and not confused with each other, and when the product is made in the form of a station with built-in several dials, then this makes the data even easier to read. Digital options are more acceptable for the middle generation, who are on short terms with any display, and for a gift to an older person, it is better to buy a standard version of the barometer.

When you choose such a gift while on vacation, keep in mind that barometers cannot be transported on airplanes - they will fail due to pressure changes. The mechanism is designed to withstand certain changes and can break even when traveling along a fairly steep mountain serpentine road, when you descend the mountain at high speed. So all this must be taken into account and the operating features of these devices must be known.

Rating

Rather, this is just a review where the best, in our opinion, models from manufacturers from different countries, including Russia, are presented.

• Item Type: Liquidless Aneroid
• Body material: plastic, polished acrylic
• Measuring range: 710-790 mm. Hg Art.
• Scale division value: 1-5 mm. Hg Art.
• Purpose: weather harbinger for hunters
• Dimensions: 140x40x160 mm
• Warranty: 12 months
• Manufacturer: Sweden

• unique design
• all inscriptions are in Old Russian language
• great gift for a hunter

• not found

• Item Type: Home Weather Station
• Location: wall mounted
• Body material: high strength wood, baroque color
• Measuring range: pressure - 710-800 mm. Hg Art., t - -20-+50 °C, humidity - 0-100%, rH
• Instrument diameters: barometer - 90 mm, thermometer - 100 mm, hygrometer - 48 mm
• Dimensions: 450x115 mm
• Weight: 1 kg
• Warranty: 12 months
• Manufacturer: Russia

• high build quality
• attractive, original design
• saves freight this type long years

• not found

• Product type: weather station
• Location: wall placement
• Case material: matte polished wood
• Measuring range: pressure - 710-790 mm. Hg Art., t - -10-+50 °C, humidity - 0-100%
• Display diameter: 90 mm
• Purpose: weather harbinger
• Dimensions: 119x443x30 mm
• Warranty: 12 months
• Manufacturer: Sweden

Barometer is a measuring device that is designed to determine atmospheric air pressure. In addition to meteorological applications, the barometer is used for environmental monitoring (for example, to certify workplaces) or in aviation (to determine flight altitude above sea level).

Figure 1. Aneroid barometer

For the first time, the barometer was invented and described in the work “Opera geometrica” in 1644 by a scientist from Florence (Italy) Evangelista Torricelli. It was a liquid mercury barometer, the pressure of which was measured by the height of the mercury (liquid) column in a tube sealed at the top and placed at the lower end in a vessel with mercury (liquid). On the day that Torricelli conducted the experiment with his mercury barometer, the weather was calm and sunny, and the mercury column stood at 760 mm. Since then, a pressure of 760 mmHg has been normal. Mercury and liquid barometers are the most accurate and are still used at weather stations. Their disadvantages are fragility, insecurity and large size.

In 1844, the French engineer Lucien Vidy, using the research of a German mathematician and physicist of the 17th century. Gottfried Wilhelm Leibniz, designed a fundamentally new, liquid-free barometer, which was called an aneroid barometer (from the Greek “aneros” - not containing moisture). Barometers built on the basis of the L. Vidi barometer are currently the most common.

At all, barometers, depending on the principle of operation may be mercury, liquid, aneroid or electronic.

- Liquid barometer- a device that uses the principle of balancing the weight of a liquid column with atmospheric pressure.

- Mercury barometer- atmospheric pressure, which can be measured by the height of the mercury column on a scale attached next to it.

- a device whose operating principle is based on changing the dimensions of a metal box filled with rarefied air under the influence of atmospheric pressure. Such barometers are reliable and small in size.

- Electronic barometer– this type of barometer works on the principle of converting the linear dimensions of a traditional aneroid pressure box into electrical signal and further processing of this signal by a microprocessor. If, instead of an aneroid box, a strain gauge is used, then the measured pressure is perceived by this sensitive element and is converted through its deformation into a change in the electrical resistance of the strain gauges of the strain gauge transducer.

However, since the topic of this article is “Barometer-Aneroid,” we will return to this type of pressure measuring devices and consider them in more detail.

So, this is a device that is intended to measure atmospheric pressure mechanically. Structurally, the aneroid consists of a round metal (nickel-silver or hardened steel) box with corrugated (ribbed) bases, in which a strong vacuum is created by pumping out air, a return spring, a transmission mechanism and an indicator needle. Under the influence of atmospheric pressure: its increase or decrease, the box, respectively, either compresses or unbends. In this case, when the bellows box is compressed, the upper flexing surface begins to pull the spring attached to it down, and when the atmospheric pressure decreases, the upper part, on the contrary, bends and pushes the spring upward. An indicator needle is attached to the return spring using a transmission mechanism, which moves along a scale calibrated in accordance with the readings of the mercury barometer (Figure 2). It is worth noting that usually, in practice, several (up to 10 pieces) thin-walled corrugated boxes with vacuum are used in series, which increases the amplitude of the pointer moving along the scale.

Figure 2. Aneroid Barometer structure.

Aneroid barometers, due to their small size and the absence of liquid in their design, are the most convenient and portable; they are widely used in practice.

Unfortunately, barometers are affected by temperature environment and changes in spring elasticity over time. Therefore, modern aneroid barometers are equipped with an arc-shaped thermometer, or a so-called compensator, which is intended to correct the instrument readings for temperature.

In general, to obtain the true value of atmospheric pressure, the readings of an aneroid barometer require various corrections, determined by comparison with a mercury barometer. There are three amendments to aneroids:

Scale correction - this correction depends on how unevenly the aneroid barometer reacts to pressure changes in different parts of the scale,

Temperature correction - determined by the relationship between temperature and the elasticity of the aneroid corrugated box and spring,

The amendment is additional - determined by a change, over time, in the elasticity of the aneroid corrugated box and spring.

The body of an aneroid barometer is usually made of valuable types of wood, such as walnut, oak, beech, cherry or mahogany. Such barometers are no longer just instruments for measuring atmospheric pressure, but interior items. However, to reduce the cost of the entire structure and make it more practical, the aneroid body can be made of plastic or metal.

Aneroid barometers presented by models:

- BAMM-1 is a barometer, which is intended for measuring atmospheric pressure in ground conditions and indoors. Included in the State Register of Measuring Instruments of the Russian Federation, therefore it can be used for certification of workplaces.

- M-67 is the most accurate and unpretentious barometer. Thanks to its design features, it is capable of operating at temperatures from -10 to +50 o C (Figure 3).

- M-110 – barometer for industrial use, included in the State Register of Measuring Instruments.

- BB-0.5M – household wall-mounted barometer. Ideal for approximate measurements of atmospheric pressure.

- BR-52 – school aneroid barometer, used as teaching aid and for conducting experiments.

Figure 3. Barometer model M67.

To carry out more accurate or longer-term measurements, as well as to verify related instruments at weather stations, weather posts and laboratories, other instruments are used. They can be either digital or mechanical. For example, the BOP-1M barometer, being an exemplary portable barometer, as a reference measuring instrument, is intended for checking barometers of various designs and devices for general industrial purposes that measure atmospheric pressure.

BRS-1M – working network barometer, intended for precise definition absolute air pressure, has a digital RS232 interface for connecting to a computer.

Meteorological barograph M-22A is a device that is intended for determining and graphically recording atmospheric pressure values ​​both indoors and outdoors, for a certain period of time (Figure 4.).

Figure 4. Barograph M-22A

The MD-13 automated digital barometer is used at weather stations for long-term (up to 1 month) measurement of atmospheric pressure with the ability to transfer measurement results to a computer.

Modern man, from childhood, has access to complex and functional electronic devices. Such accessibility of technology has led to the fact that classic devices attract almost no interest and gather dust on shelves in complete oblivion. All these compasses, thermometers and barometers, with the help of which our grandfathers and even our parents navigated the world and assessed the state of the environment, seem outdated and boring toys. And in vain. It is precisely about the barometer that I would like to talk in more detail. Because, even despite the obvious and rapid technical progress, this device remains an indispensable assistant to determine atmospheric pressure. And it influenced and influences both us and our ancestors equally. And even today, when everyone may have a portable weather station in their pocket, its operation is still based on the principle of that same barometer.

Of course, now barometers differ from their ancient prototypes - both externally, structurally, and functionally. But the essence of their action remains the same, and it is indispensable for every person who does not live in conditions of complete isolation from the world around and breathes air. Atmospheric pressure affects everyone and everything. And, if we usually notice the weather and its phenomena, such as the sun, rain, wind, then it is worth thinking about the fact that all these manifestations can be predicted in advance by measuring the atmospheric pressure with a barometer. Such measurements help weather-dependent people and those who are simply going on a long trip and want to know what the weather will be like along the way to prepare in advance for upcoming changes. To do this, you can simply watch the forecast on TV or on the Internet, but it is much safer to control what is happening yourself. And for this it won’t hurt to learn how to use a barometer.

Structure and functions of a barometer
A barometer is a device that measures atmospheric pressure and displays the results of these measurements in human-understandable quantities. But it does not have artificial intelligence and does not have direct communication with space satellites. So how does he do it? Yes, very simple. The operation of the simplest barometer was based on the ability of a liquid to move under air pressure. The first liquid used for this purpose was mercury, enclosed in a thin vertically oriented glass tube. The author of this design, Evangelista Torricelli, back in 1643, came up with the idea of ​​lowering a hollow tube sealed at the top end into a vessel with mercury and observing how the “mercury column” rises or falls under pressure.

Rumor has it that Galileo himself inspired him for this ingenious invention at that time. But, be that as it may, the mercury barometer was a rather dangerous device, and therefore, almost from the moment of its creation, the search began for other options that did not involve the use of toxic liquids. It was possible to find a satisfactory method only in the middle of the 19th century, when Torricelli’s compatriot Lucien Vidi showed the world a mercury-free and generally liquid-free barometer he had invented, which was naturally dubbed an aneroid (in Latin - “without liquid”). The aneroid barometer immediately appealed to sailors because it could withstand the pitching and shaking of a ship, and they still use similar devices to this day. In fact, there is nothing complicated about them either: just a metal box with thin walls, inside of which there is a vacuum or very rarefied air. Air pressure bends the metal, and it, in turn, pulls the attached spring. An arrow is attached to the spring, indicating the scale divisions.

The main advantage of this design is safety and accessibility. The main disadvantage is the low accuracy compared to the mercury column. Therefore, no matter how funny it may seem, aneroid readings are sometimes double-checked using liquid barometers. For travelers and yachting fans, the accuracy of the readings is very important. Oddly enough, many of them still use classic aneroids - either there is a certain charm in this, or it is due to conservatism. Although today the problem of measurement error has practically disappeared, and traditional models of barometers play the role of status souvenirs and stylish decor rather than measuring instruments.

If you need to find out the atmospheric pressure, it is much easier to use a compact electronic barometer. In him metal plates successfully replaced by microscopic capacitors and circuits, sometimes by crystals. Such a digital device can easily be integrated into wrist watch and/or radio receiver, does not take up much space and does not disappoint in the data provided. Moreover, in Lately There are even barometers built into mobile phones, and special applications for smartphones that not only measure pressure, but are also linked to GPS navigators. In other words, there is nothing easier than finding out the current and future state of the atmosphere, the weather for tomorrow in different parts of the globe. But, if not for the first barometers, invented almost half a millennium ago, one could only dream of this newfangled comfort.

Rules for using a barometer
So, there are several types of instruments for measuring atmospheric pressure, each of which is, in fact, a barometer, and has its own characteristics, advantages and disadvantages. But, if you still decide not to limit yourself to ultra-modern devices and master the use of a classic barometer, then there are good reasons for this. In some cases, this may be a desire to understand the structure of traditional technology, a desire to classic style in the interior and everyday life, or just curiosity. It happens that a desktop barometer is given as an expensive souvenir, and it’s a pity not to use a new beautiful thing. In any case, you will find the following tips for using a barometer at home useful:

1. Mercury barometer will show atmospheric pressure in millimeters of mercury. Mercury (possibly another, safer, colored liquid) is inside the flask, which is marked with divisions. The size of each division depends on the size of each specific barometer; check it to avoid errors. Then just look at how high the column inside the flask has risen and what number it points to. Please note that the barometer must be strictly at eye level, otherwise the readings will be distorted. Try not to move the device or touch it with your hands at all, because its sensitivity is very high and the data may be lost.
   Mercury barometer is the simplest device, and it only shows the state of the atmosphere directly around itself, in the room where it is placed. Therefore, using it to estimate the pressure outside the window or even in the next room can be problematic. To do this, you will have to move the barometer to a new place and wait until it adapts to the new conditions. However, this particular barometer has long been the most common device for measuring pressure, and mastering it is no more difficult than learning to use a household thermometer. Today in most residential buildings and offices, more modern and functional barometers are used, but if necessary, a mercury model can still be found and purchased at a pharmacy or hardware store.
   
2. Aneroid box. It can be placed on a table, hung on the wall in the bedroom (this can still be found in the homes of older people, whose well-being depends on atmospheric changes) or attached to a window glass. The size of this device can vary, from a very miniature round to a “puck” with an impressive diameter. But outwardly it always looks like a dial with a moving arrow above it. On the dial, in addition to numerical designations, words can be written, such as: “Clear”, “Dry”, “Variable”, “Rain”, “Storm”, etc. As you might guess, these tips serve to make using the barometer even easier.
   By and large, you just need to look at what word the barometer needle is pointing to at the moment. All technical subtleties will remain beyond your attention and should not worry you, because the necessary information in a simple and understandable form is already before your eyes. For your part, you can participate in drawing up a short-term forecast and observing changes in the atmosphere if the design of your barometer requires not one, but two arrows. You can turn the additional arrow using the same principle as you use to set a mechanical alarm clock. If you compare it with the second arrow, then after a while you will be able to notice whether changes have occurred relative to this position - that is, whether the pressure has changed, and, if so, in what direction.
   
3. Electronic barometer even easier to use than the classic aneroid. Most often it is called a weather station for its ability to combine several functions at once and fairly detailed monitoring of weather changes and forecasts. The only difficulty you may have when reading the readings is confusion among the many numbers and icons displayed on the digital barometer display. Indeed, in pursuit of external effectiveness and design delights, many electronics manufacturers forget that any device should, first of all, be convenient in practice. This is the main task of the ergonomics of the barometer case and screen, and not at all in its futuristic and amazing design.
   An electronic barometer usually has a housing and a flexible sensor designed to be placed outside a window. The end of the sensor sensitively records any changes in humidity, pressure, strength and direction of the wind outside, and the screen on the body immediately (or with a minimum time delay) shows you information about this. Even in the simplest digital barometer models you can see the current time, air temperature (outdoor and/or indoor), air humidity and, of course, atmospheric pressure. The latter is traditionally expressed in conventional “millimeters of mercury”. And although there is no mercury column inside the barometer, these units of measurement are considered generally accepted when we're talking about about measuring pressure. Most likely, your electronic barometer is not limited to digital indicators and at the same time diversifies the data with pictures-icons depicting the sun, clouds or rain.
   

And finally, it remains to decide what type of barometer to choose for personal use. There can be no strict recommendations here, and you are free to follow your own taste, fashion trends, interior style or simply the circumstances. The main thing is that it is convenient for you to use it, and information about atmospheric pressure and other weather parameters was visual, understandable and easy to understand. After all, the primary function of a barometer is precisely this: to promptly and as accurately as possible notify you about the state of the environment. Focusing on it, you can plan your day in advance, which is especially important for representatives of active professions, enthusiastic hunters, fishermen and tourists. For them, the barometer is simply irreplaceable, and therefore will be an excellent gift for any occasion or just for no reason, as a sign of respect for their activities.