Many people set up and calibrate their own barometers. The online store offers to buy mechanical aneroids, which are easy to study and fix yourself if necessary. In order to properly configure home barometers, follow our tips below.

How do you know if the barometer needs to be adjusted?

Check the reading on your meter. Track: compare his data with those that are broadcast on radio, television, or with the summary of the hydrometeorological center. For comparison, take the information that is given specifically for your region. It is impossible to compare the readings of the home barometer with the data for the neighboring area: at a distance of several kilometers, these figures can vary significantly.

The normal error can be up to 8 mm. rt. Art. If your barometer does not exceed the permissible error value, then you do not need to adjust it. If the device displays data with exactly this or greater error, then it needs to be calibrated. It is not difficult to do this, after reading this article it will become absolutely clear how to properly configure barometers. Online store presents mechanical models that are easy to understand, just follow our step-by-step advice.

How to set up a barometer?

· Find a thin black arrow. It is called an index and we need it in order to correctly set the sea level at which the device is located.

· There is a large adjustment screw on the back of the barometer. Take the usual wrench the correct size and use it to turn the adjusting screw so that the black arrow points to the correct sea level for your city.

· Check the correct position of the arrow again.

· Check the correct barometric pressure data for your location. Take advantage of the news bulletin or weather forecast.

· Use the center knob of the barometer to turn the second hand to accurately indicate this data.

· Hang the barometer on the wall or place it on a table. Make sure it works properly: tilt the entire body of the device about 45 degrees. If the thin black index hand turns clockwise, then your barometer is okay: this is the normal reaction of the device to a change in position. But if the arrow does not make a turn, contact a specialist. There may be some trouble or a problem with the device.

When checking your home barometer, remember to check accurate reports. In addition, it is desirable that the device is located at the same altitude above sea level at which you are - otherwise the weather forecast made using such a device will not make any sense. Also pay attention to the correct installation or mounting of the barometer: only the correct location of the device will make its readings accurate. But, on the other hand, remember: it makes no difference whether the device will be in an apartment or house, or be on the street. When properly installed, the barometer will show changes in atmospheric pressure correctly.

Most barometers do not require frequent calibration or adjustment. It is a durable device that is designed to last for many years. Before taking any action, check carefully whether there really is an error in his readings.

Atmosphere pressure
Remember, in the novel "The Golden Calf" by Ilf and Petrov, the Great Combiner shared with Adam Kozlevich the news that each of us, it turns out, is being pressed by a column of air with a force of 214 kilos? Yes, the atmosphere has weight, and it weighs on us. But each time is different, and it depends on the weather. When the sun shines brightly, it crushes more, when it is cloudy and rain is falling, it crushes less. Moreover, a change in atmospheric pressure, as a rule, occurs earlier than a change in weather, therefore, having detected a change in pressure in time, we can predict whether it will rain or snow tomorrow, or maybe vice versa - it will be sunny and dry. Knowing about the state of atmospheric pressure is also useful for people suffering from cardiovascular diseases, hypertension or hypotension, as well as other meteorological citizens. This will allow them to take measures in advance in order to better cope with the weather cataclysm.

For these purposes, a special device called a barometer is used. Back in 1644 (according to some sources, in 1643), Galileo's student, the Italian physicist and mathematician Torricelli, discovered that if a thin glass tube was filled with mercury and one end of this tube was lowered into a cup filled with mercury, then not all of the mercury would pour out from the tube, part of it will remain. Moreover, the level of mercury in the tube will depend on the weather outside the window.
This is how the first mercury barometer was born, and the value of atmospheric pressure is still measured in millimeters of mercury. And even with the introduction of the international metric system for measuring the SI, hectopascals have not been able to displace the good old millimeters of mercury. These millimeters could not displace even the bars, despite the name of the device -.

As in the remote Middle Ages of the 17th century, at weather stations, pressure is still measured with mercury barometers, since this method is considered the most accurate. Mercury is not a very healthy substance, therefore one end of a tube filled with this liquid metal is sealed tightly, and the other is dipped into a container with liquid.

In everyday life, the so-called aneroid barometer, that is, liquid-free, is often used.

The sensitive element of such a device is a small corrugated box, from which air is slightly evacuated to create a slight vacuum. This box decreases or increases in size depending on the value of atmospheric pressure, and an arrow connected to the box by means of springs and levers indicates its value on the scale. Aneroid barometer is not only a device, it can be a souvenir and a wonderful gift. He is like wall-mounted or desk clock, often serves as an interior decoration.

The simplest barometer you can make yourself from a twig coniferous tree... If you take a sprig of fir or pine, leave one long needle on it (and remove the rest) and fix it vertically on a plank so that the needle does not interfere with its movement, then the needle will rise in clear weather and descend towards the rain. And also electric transport, which has a contact network - a tram, a trolleybus, an electric train, can act as a barometer. The fact is that at high atmospheric pressure, sparks that sometimes arise between the wire and the current collector will have a bright blue, slightly purple color. At normal pressure, they will be blue-blue, and at low pressure, the tint will become slightly greenish.

How do I use the barometer?

The barometer is falling!
- Hold it, or it will break!
Quite a famous pun, isn't it? Yes, in everyday life, with a sharp drop in pressure, it is often said that the barometer "falls".

Using the barometer is very easy - you just need to look where the arrow of the device is pointing. On the scale, in addition to divisions indicating absolute values, there are also zones designated as “storm”, “rain”, “variable”, “clear”, “dry”, or in other similar words. Usually the device has two arrows - one is movable, connected with a sensitive element (aneroid box), the other you can turn yourself like an alarm clock bell hand. What is it for? If you combine it with a movable arrow indicating the state of atmospheric pressure at the moment, you can observe in which direction the movable arrow will deviate after a while. You will know if the pressure is increasing or the barometer is still falling.

Finally, I would like to cite one anecdote. At the exam, a student was asked: how to measure the distance from the ground to the roof using a barometer high-rise building? The student immediately suggested several ways of measuring, for example, throwing the barometer off the roof, counting the time of the fall using a stopwatch and, knowing the mass of the device, calculate its average speed - using it, you can also calculate the height. The second way is to measure the diameter of the barometer with a ruler, then, applying it to the wall, climb the fire escape to the roof and find out the height of the building in barometers, after which it can be easily converted to centimeters or meters. The third way is to go to the house manager, show him the barometer and say:
- Look, what a beautiful thing, I'll give it to you if you tell me the height of this house!

In fact, the height of a building is calculated from the pressure difference between the ground and the roof of that house. After all, the higher we go, the lower the height of the air column, which so amazed the imagination of Ostap Bender with its mass. Therefore, taking readings of a barometer somewhere on the twenty-fifth floor, it should be borne in mind that the normal pressure for this height is somewhat lower than at the surface of the earth.

Types of barometers: A mercury barometer consists of a tube filled with mercury and a container with liquid. One end of the tube is sealed, and the other is dipped into the liquid. The aneroid barometer does not use liquid; a corrugated box with slightly rarefied air acts as a sensitive element in it. This box changes size slightly depending on atmospheric pressure, these changes are displayed by an arrow attached to it using sensitive springs. Aneroid barometer can often be found in everyday life, beautifully designed, it can serve as an unusual gift, not only beautiful, but also useful, especially for a meteorological person.

Measurement method: If you have a home barometer, it will not be difficult to measure atmospheric pressure. You just need to look at what division the arrow points to, often home barometers have additional designations "clear", "variable", "rain". Moreover, there are barometers with 2 arrows - one of them is movable and indicates the pressure, and the second can be moved independently. Having installed it in the zone indicated by the movable arrow, after a while you can check the reading of the device and understand whether the pressure rises or falls. It is more difficult to determine the level of atmospheric pressure without a barometer. To do this, you can watch the sparks from the tram or trolleybus antennas; at high pressure, the sparks will be bright blue, and at low pressure, slightly greenish. In nature, you can use a branch of a coniferous tree. To do this, remove all the needles from it except one, then fix it vertically on the board and observe. In clear weather, the needle will rise, and fall to the rain. However, it is still more convenient to have a ready-made device on hand.

Benefits of Measuring Barometric Pressure: Needless to say, it helps meteorologists predict the weather. First of all, readings of atmospheric pressure are needed by meteorological people. The pressure level begins to change before the weather changes, which means that by observing the pressure variable you can prepare for possible problems with health. People with cardiovascular diseases, hypotension and hypertension, migraines and other diseases react to the weather. Timely intake of the necessary medications will reduce the risk of an exacerbation of the disease during a period of changing weather.

The atmospheric pressure level is not the readings that the announcer lists during the broadcast of the weather forecast on TV or radio. These are indicators that can significantly improve the quality of life for you and your family, if you understand them and monitor changes in pressure. After all, information about a drop in blood pressure may prompt you to bring an umbrella with you.

After reading from various sources about the fact that the biting activity is directly, or rather not quite directly, but still, it is connected with sharp drops atmospheric pressure. I decided to get a barometer. According to reviews on the Internet, I chose a barometer manufactured by OJSC "Utes" BTK-SN-14. How to check it on the spot (in the store) did not have the slightest idea, so after a cursory inspection, I paid and dragged him home.

At home, I immediately hung it on the wall, and, all happy, let's measure the pressure;)
Some time later, I decided to believe him. I called the local weather station and was surprised and upset at the same time. My barometer was lying by 10 mm Hg! That's a lot! According to the attached passport, it was no longer possible to correct it, tk. it indicates that the adjusting screw can be rotated no more than 45 degrees, and with such a difference, it had to be turned by about 90 degrees.
Deciding that I will not scoff and twist the adjustment at random, was about to carry it back to the store. Because The store in which I bought it was closed for a break, I went to the next one where the same barometers were sold, but one and a half times more expensive (normal practice in our city). Having pretty much chased the seller, I reviewed all the barometers that they had, and thanking them went home. :)

I changed my mind to change or hand over my defective barometer, tk. everything I saw in the store showed God knows what, and the assembly of mechanisms looked different for everyone. I decided that I would not get anything better, but I would try to figure out the reason and (if possible) eliminate the marriage on my own.

As shown by the autopsy, the fault is the curve assembly. The barometer itself is not complicated. On some (I don't remember) Internet resource I read, then these barometers are made according to a patent of a German mechanism. In which everything is thought out for not complicated assembly and adjustment, but our crooked workers, as always, will be able to pack even the best and most reliable thing. The barometer is assembled in a "pozgildyaiski" manner, and with the settings, twisted almost all the way, it is displayed in a less plausible state of readings.
Having disassembled it almost to the screw, I assembled it as expected. After that, he began to look more neat and the adjusting ranges fell into place. The scatter of readings with the meteorological station was reduced to + -1 mm Hg.

So what did I find. The scoreboard with the rulers was rotated relative to the mechanism by about the same 10 mm Hg. The fix is ​​very simple. It is enough to unscrew the four screws under the glass frame to rearrange the display, so that all three points indicated in the photo (in red) are approximately on the same straight line.

It was much more difficult to fix another significant "jamb" of the manufacturer. The aneroid (sensing element of the barometer) was not located in the center of the mechanism. Therefore, all the normal positions of the linkage "crawled". This is noticeable by the misalignment of the adjusting screw and the hole in the housing (yellow arrow in the bottom view, in the photo everything is already correct).

Correct this by simply loosening the adjusting screw, then moving the aneroid to right place, Will NOT succeed. Because possible misalignment and, as a result, sticking of the linkage mechanism. To do everything right, you need to disassemble the barometer and adjust the position of the levers inside, after loosening the aneroid fastening, so as not to bend the delicate parts of the mechanism (they are still there;). I think it is not necessary to describe in detail the entire assembly / disassembly process (and who needs it, write, I will tell you).

I'd better tell how to choose an initially correctly assembled barometer in the store.
I think you've already guessed about some points =)
-The first thing that you should pay attention to is (the most important) that the adjusting screw on the back of the case is located as much as possible coaxial with the hole for it. (yellow arrow in the photo) Otherwise, it is practically guaranteed that the aneroid and the whole mechanism are skewed.
-Second, it will be more difficult. A ring gear, in the form of a trident (indicated by a green arrow). When the device reads about 748 mm Hg. (provided that the scale of the device is set correctly, as described below), the branches of the "trident" should be as parallel as possible to the indicating arrow. This indicates the correct installation of the indicating arrow of the device relative to the mechanism.
-Third, this is the correctness of the installation of the scale of the device relative to the mechanism. The axis of the indicating arrow, the axis of the toothed sector ("trident") and the axis of the thermometer (red arrows) must be aligned.

If the last two points are easily corrected and, in essence, do not affect the operation of the barometer, then the first point entails a real violation of the correct operation of the barometer. In my case, due to the skew of the mechanism, with the readings of 740-750 mm Hg, the "trident" was "driven" almost to the left dead center of its stroke. Those. he could still show less pressure, but with increased pressure, "the trident would have rested against the travel stop, significantly not reaching the maximum value indicated on the scale.

All of the above refers to the BTK-SN-14 model of OJSC "Utes"; there may be differences on other models. I would be glad if this information helps someone with the purchase.

PS For those who are "in the tank", WARNING: the author does not bear responsibility for his own barometers, due to the "crooked hands" or incorrect interpretation of this article. Self disassembly and adjusting your barometer can lead to its breakdown and loss of the possibility of warranty repair. In other words: I'm not sure - DO NOT GET IT!

Comments:

The barometer is a key tool in the practice of weather forecasting. The barometer measures atmospheric pressure, which is determined by the weight of the air above us (from the upper boundary of the atmosphere to the sea surface). If the pressure is high, then this means that there is a large number of air above us, if low, then there is less air than anywhere else, farther from us. This cannot be seen by eye, since the air is invisible.

We are interested in atmospheric pressure because it informs us about the distribution of air masses around us and about the expected winds that occur when air flows from areas of high atmospheric pressure to areas of low pressure. The greater the pressure difference over neighboring territories, the stronger the wind will be.

In weather forecasts and on weather maps, it is customary to reflect atmospheric pressure in millibars (mb). We need to know whether the pressure transmitted by the official forecast or taken from the barometer is high or low, and its change is large or small. To do this, you must remember that the "standard" atmospheric pressure is 1013 mb, but for each location and season, it may slightly differ from this figure.
On meteorological maps, the pressure is indicated only by the last two digits (the previous ones are omitted). 1024 will be shown as "24", or 996 as "96". In most cases, the actual pressure in the centers of cyclones and anticyclones is written in full and underlined, but individual isobars (lines of equal pressure) have only two digits. Usually isobars are drawn at 4 mb intervals on USA maps, although other country maps can range from 2 mb (Australia) to 5mb on European maps.

Barometer types
The first barometer was invented by Evangelista Torricelli in 1643. Torricelli was often spoken of as Galileo's student, but he only worked with him for 3 months before the latter's death and invented his first mercury barometer a few years later.

Torricelli Mercury Barometer

The device was a hollow glass tube, closed at one end and filled with mercury, which was lowered with its open end into a vessel with mercury. The air pressure on the open surface of the mercury balanced the pressure of the column of mercury in the tube, and its level turned out to be at a certain height - about 760 mm. mercury column. Of course, such a device was bulky and fragile and could not have wide application in practice.
Further improvement of the barometer followed the path of abandoning mercury and using sealed containers with a vacuum inside, and in 1847 the first aneroid barometer was designed by another Italian, Lucien Vidi. Aneroid means no liquid. This type of barometer is still used today.

Aneroid barometer

The “heart” of the instrument is a sealed corrugated metal cylinder (bellows), from which air is partially evacuated (1). When the external air pressure changes, this cylinder expands or contracts and this movement is transmitted through a system of levers (2) and a thread (3) to the axis of rotation of the arrow (4), which shows us the pressure on the scale of values ​​(5). The device is placed in a housing (6) with a glass above the scale (7).

Another instrument useful in meteorology is called a barograph. This is the same aneroid barometer, which can record pressure values ​​with an ink line for a certain period (usually a week) on paper tape wrapped around a clockwork drum.

Barograph

The advantage of this device is that along this line we can directly observe the so-called barogram - the change in pressure over time, which in fact interests us most.

Barogram - a graph of the baric trend

This is very valuable information for weather forecasting. With a barograph, you will be relieved of the need to constantly record barometer readings and then plot baric trend curves from them.
Continuing the conversation about the barometer as a device, it should be noted that in the last decade, electronic barometers have appeared on the market. different sizes and accuracy. There are even barometers and barographs built into the wristwatch. Some of them work on the principle of a conventional aneroid, but without a mechanical system of levers, but by measuring the change in the capacitance of an electric capacitor, the plates of which are located at the ends of a corrugated cylinder. Others use a different principle by measuring air pressure on a sensitive crystal.

Digital barometer

Digital barographs are also available for use, and there are advantages here, as it is difficult to ensure the correct operation of a traditional barograph in an in-flight environment.

The value and price of a good barometer
In my opinion, a GOOD barometer is a great value. A traditional aneroid barometer would be the obvious choice. In most cases, knowing whether the pressure is falling or rising can be enough to judge whether bad weather is coming or vice versa. This judgment can be made with almost any working barometer, as long as you monitor it periodically. But often we need to know the true, accurate value of the pressure. Moreover, if the pressure changes, we must be sure that it changes exactly as the instrument shows. I have seen barometers that beautifully showed the change in pressure, but in a very narrow range, and did not react at all when the pressure went outside this range.
Knowing the exact value of pressure is very important when you operate with a weather map. By measuring the speed and direction of the wind, you can calculate the corresponding pressure at your point of location, and by measuring the existing pressure with a well-calibrated barometer, you can judge how correct the information on the map you received is. The key point here is often not so much the quality of the barometer as its calibration, finding out the error and take it into account.
If you pay $ 150 - $ 200 for the device, it should show correct values... Unfortunately, not in all cases. You can often pay big bucks for a barometer with an expensive bronze case and a beautiful dial and a completely unusable movement. Buy the barometer from reputable dealers and specialized stores.

Taking readings and maintaining the barometer
Check the accuracy of your barometer regularly on official radio. There are three factors that affect the meter reading during testing. The first is the instrument's height above sea level - the higher, the lower the pressure reading from the instrument will be. Second, there is a “zero” point of the instrument setting. It is regulated by a screw, by turning which you can move the arrow left and right, and every good barometer should have such an adjustment. For correct installation arrows the device must be located at sea level. Once you have received the pressure data, set the arrow to that value. And thirdly, the time of the radio message can and will differ from the time of the pressure measurement at the meteorological station. Try to figure out this delay.
Barometer - thin and precise instrument and taking readings from him requires attention and accuracy. Small changes in values ​​can mean a lot in some cases. The barometer should be easily accessible so that the position of the thin arrow at small scale divisions can be clearly seen, especially at night. You must look at the scale perpendicular to its surface, otherwise you will get an incorrect reading due to the parallax effect. Fig G110.

Speaking about caring for a barometer, it should be noted that it requires the same respect for itself as any accurate measuring device... But there are several features stemming from its nature. Avoid placing the instrument in an environment where atmospheric pressure is outside the range of the barometer. So, transporting it in an airplane can become fatal, since at an altitude of 10 km the atmospheric pressure is only 300mb, and although the pressure in the cockpit is compensated for, it rarely exceeds 800mb, which is outside the operating range of the device, and in the cargo compartment the pressure is generally equal to the external ... Be careful when transporting the barometer in your car. The windows should be open when you slam the door - this way you avoid a sharp surge in pressure in the cabin when you close the doors. I can’t say how fast descending a car from a hill can damage the barometer, but if our ears sense this, then the pressure change clearly lies outside the working area of ​​the device.

Some tips for choosing a barometer
We can rarely find a combination of all the ideal properties of a device with an acceptable price, so trade-offs are inevitable. But there are a few things to look out for when buying a barometer.

1. Good travel and bellows.
You cannot judge this simply by looking at the instrument, but if it is possible to look inside and you can see the bellows, then it is useful to know that the larger its size, the better the instrument's travel and its performance.

2. The size of the dial.
Bigger size preferable because it is easier to take readings from it. The 10cm diameter of the dial can be considered the minimum. 12-15 centimeters are better, but they are more expensive.

3. Scale divisions
A 1 mb scale is preferred.

4. Dial surface
A shiny or silver-plated surface can sometimes act as a mirrored surface and help see the reflection of the arrow, making it easier to take readings.

5. Temperature compensation
Ask your dealer how good the temperature compensation of the barometer is. The temperature, for example, in a yacht below deck can reach 60 degrees, and in the tropics up to 100 degrees. centigrade

7. Case
I prefer barometers with a light body. Any addition of bronze serves as decoration and only adds weight and cost, without adding anything to the functionality of the appliance.

Pressure readings and baric trend
Speaking about the pressure values ​​that the barometer shows us, it should be noted that pressure above 1025 mb is considered “high”, and below 990 mb - as “low”. But, of course, everything is relative - atmospheric pressure of 1005 mb will be rather "high" if it is lower in the surrounding regions. You should always take into account the peculiarities of the region. Usually high pressure there is good weather with light winds, while at low pressure (below 1000 mb) bad weather with fresh and strong winds with the sky completely covered by clouds and with rains. More information about using the barometer in weather forecasting will be described in the article "Weather forecast" (forecast by barometer). Here we will focus only on a few important points.
Noting the importance of the actual readings of the barometer at a given point in time, it must be said that the most useful in using a barometer is to determine the baric trend - the change in pressure over time.
It is generally accepted that a pressure drop of 1mb per hour deserves our attention. A drop of 2-3mb per hour may mean the arrival of a storm, although we still have calm weather on the spot. Examining many records of baric trends as storms approach, it is observed that they are usually accompanied by a slow steady drop of 2-3 mb every three hours for half a day until the pressure drop accelerates. Severe storms during their passage can cause a drop in pressure of 5-10mb per 3 hours, but the record falls belong to the passage of the eye of a tropical storm - up to 12 mb per hour!
It is important to know what kind of pressure drop can be dangerous for him. Remember the 4-5-6 rule. It means: a pressure drop of 4 or 5 mb in 6 hours is a signal for a change in the weather for the worse ...

From Weather Trainer by David Burch
Translated by S. Svistul

The physical nature of atmospheric pressure will be described in detail in the article "Where does the wind come from?"