Mankind learned to measure temperature about 400 years ago. But the first instruments, reminiscent of today's thermometers, appeared only in the XVIII century. Gabriel Fahrenheit was the inventor of the first thermometer. In total, several different temperature scales were invented in the world, some of them were more popular and are still in use, others have gradually fallen out of use.

Temperature scales are systems of temperature values ​​that can be compared with each other. Since temperature is not a quantity subject to direct measurement, its value is associated with a change in the temperature state of a substance (for example, water). On all temperature scales, as a rule, two points are fixed, corresponding to the transition temperatures of the selected thermometric substance into different phases. These are the so-called reference points. Examples are the boiling point of water, the hardening point of gold, etc. One of the points is taken as the origin. The interval between them is divided into a certain number of equal segments, which are single. One degree is universally accepted as a unit.

The most popular and widely used temperature scales in the world are the Celsius and Fahrenheit scales. However, we will consider the available scales in order and try to compare them in terms of ease of use and practical benefits. The most famous scales are five:

1. The Fahrenheit scale was invented by Fahrenheit, a German scientist. In one of the cold winter days In 1709, the mercury in the scientist's thermometer dropped to a very low temperature, which he proposed to take as zero on the new scale. Another reference point was the temperature of the human body. The freezing point of water on its scale was +32°, and the boiling point +212°. The Fahrenheit scale is not particularly thought out or convenient. Previously, it was widely used in the present - almost exclusively in the United States.

2. According to the Réaumur scale, invented by the French scientist René de Réaumur in 1731, the freezing point of water is the lower reference point. The scale is based on the use of alcohol, which expands when heated, a thousandth of the volume of alcohol in the tank and tube at zero was taken as a degree. This scale is now out of use.

3. According to the Celsius scale (proposed by the Swede in 1742), the temperature of the mixture of ice and water (the temperature at which ice melts) is taken as zero, the other main point is the temperature at which water boils. It was decided to divide the interval between them into 100 parts, and one part was taken as a unit of measurement - degrees Celsius. more rational than the Fahrenheit scale and Réaumur scale, and is now used everywhere.

4. The Kelvin scale was invented in 1848 by Lord Kelvin (English scientist W. Thomson). On it, the zero point corresponded to the lowest possible temperature at which the movement of the molecules of a substance stops. This value was theoretically calculated when studying the properties of gases. On the Celsius scale, this value corresponds to approximately - 273 ° C, i.e. zero in Celsius is 273 K. The unit of measurement of the new scale was one kelvin (originally called "degree Kelvin").

5. (by the name of the Scottish physicist W. Rankin) has the same principle as the Kelvin scale, and the dimension is the same as the Fahrenheit scale. This system has not been widely used.

The temperature values ​​that the Fahrenheit and Celsius scale gives us can be easily converted into each other. When translating “in the mind” (that is, quickly, without using special tables) Fahrenheit values ​​\u200b\u200bin degrees Celsius, you need to reduce the original figure by 32 units and multiply by 5/9. On the contrary (from the Celsius scale to Fahrenheit) - multiply the original value by 9/5 and add 32. For comparison: the temperature in Celsius is 273.15 °, in Fahrenheit - 459.67 °.

Temperature is a physical quantity that characterizes the thermodynamic state of an object. Currently, there are several main methods for measuring temperature.

Celsius temperature

In Russia and a number of other countries, including European ones, the most common parameter used to measure temperature is the degree Celsius. It got its name from the author of this temperature scale, Alexander Celsius, who put forward his proposal in 1742.

Initially, the idea of ​​Celsius was based on the basic states of aggregation water: so, its freezing temperature was taken as 0 degrees. Thus, temperatures below 0, that is, those at which water is in a solid state, were referred to negative temperatures. The boiling point of water was taken as 100 degrees: these reference points made it possible to calculate a range of 1 degree Celsius.

Subsequently, the Kelvin scale was developed, taking absolute zero, that is, the minimum physically possible temperature, for 0 degrees Kelvin (or 0), the Kelvin and Celsius scales were brought into line with each other. Now, in order to set the temperature of a substance in degrees Celsius, you need to add 273.15 to the temperature on the Kelvin scale.

Fahrenheit temperature

The German scientist Gabriel Fahrenheit developed his scale almost simultaneously with Celsius: in 1724. He, like Celsius, took into account the state of the water, but he designated them with other numbers. So, water on the Fahrenheit scale is 32 degrees, and the boiling point is 212 degrees. Based on this temperature range, the value of one was measured, which is 1/180 of the difference between the freezing and boiling points of water in degrees.

Relationship between Celsius and Fahrenheit

To implement temperature values ​​from the Celsius scale to the Fahrenheit scale and vice versa, there are special formulas: for example, Celsius temperature \u003d (Fahrenheit temperature - 32) * 5/9. For example, 120 degrees Fahrenheit would equal 48.9 degrees Celsius according to this formula.

For the reverse translation, you can use the following formula: Fahrenheit temperature \u003d Celsius temperature * 9 / 5 + 32. For example, 20 degrees Celsius in this formula would be 68 degrees Fahrenheit. Moreover, both of these formulas can also be used to convert negative temperatures in Celsius to the Fahrenheit scale.

Not only scientists in scientific works are guided by temperature indicators, but also ordinary people planning to go out and not knowing what clothes to prefer. IN different countries there are their own, more popular measurement systems. Russian inhabitants are familiar with the Celsius scale; in America, the development of Fahrenheit is more familiar.

Measurement in Celsius

In Russia and most European countries, when talking about temperature indicators, people mean the measurement in Celsius. The temperature scale was invented in 1742 by Alexander Celsius. He was an outstanding person who created a textbook on arithmetic, took part in a 4-year journey and visited famous astronomical institutions. Nevertheless, the name of the Swedish scientist does not leave our lips thanks to his famous scale, which has 100 divisions and was developed by analyzing the possible states of water.

The theory is based on features of water modification. Water freezes at readings below zero. The temperature indicators corresponding to the process of turning water into ice are called negative. The process of boiling water is possible at a mark of 100% ( familiar look scale was given by Linnaeus, according to the idea of ​​Celsius, water boiled at 0 degrees, and melted at 100 degrees). These polar marks gave the scientist the opportunity to calculate an indicator equal to 1 degree.

Then the Kelvin scale came into use, taking into account minimum temperature, which is 0 degrees. These scales were brought into line. To name the temperature indicator of a substance, calculated in Celsius, you need to add to the temperature mark on the scale developed by Kelvin 273,15 .

Fahrenheit temperature

Measurement on this scale is a common occurrence. Often, foreign medical devices and meteorological developments measure temperature on the Fahrenheit scale. We owe this system of temperature measurements to the Dutch scientist Fahrenheit; among his developments are alcohol and mercury thermometers.

In the 20s of the XVIII century. the physicist presented his own temperature scale to the Royal Society of London. In the initial version, the temperature of the saline solution (water, ice and ammonium chloride in equal parts) was taken as the base point. Stable performance could be achieved at zero (-17.78 degrees Celsius). At the mark indicated by Fahrenheit as 32 degrees, the mixture began to melt. The third indicator indicated optimal temperature human, equal to 96 degrees.

How to explain the presence of fractional indicators? Perhaps they were obtained due to the fact that the zero mark was chosen in the winter in the city of Gdansk. Subsequently, the Dutch scientist had to practice to obtain a well-reproducible value; then brine began to be used. The scientist did not have the opportunity to get a high-quality saline solution for work. These shortcomings could not prevent the popularity of the temperature scale.

The Fahrenheit scale was especially loved in the middle of the last century by English-speaking scientists, it was used by industry and medicine. Then the Europeans began to give preference to the system developed by Celsius. To this day, Americans measure temperatures in Fahrenheit; for them it is clear that it is better to keep the room temperature in 68°F.

British publications in weather reports follow this approach: they indicate indicators in Celsius and give a translation for the Fahrenheit scale. This allows people to choose their own degree reference system and lean towards designing one of the pundits past centuries.

How do temperatures compare on different scales?

There are convenient formulas that allow you to quickly translate indicators. To understand what value on the Fahrenheit scale is the temperature mark in Celsius, it is worth using special formulas. The Celsius temperature can be calculated as follows - the Fahrenheit scale mark is 32, multiply the resulting value by 5/9. So 120 degrees Fahrenheit is equal to 48.9 Celsius.

How to calculate the Fahrenheit temperature from the available data in Celsius? We perform the following mathematical operation: the value of the Celsius scale * 9/5 add 32. 20 degrees European system temperature measurements are 60 degrees Fahrenheit.

Temperatures in degrees Fahrenheit are no longer exotic. It is very often indicated on many foreign instruments, especially on medical and meteorological thermometers. The Fahrenheit scale is the most popular non-SI temperature scale. We decided to dig a little into history and present for the curious readers of our portal the history of the creation of this very old, but still popular temperature scale in some countries.

In many reference books, including the Russian Wikipedia, Daniel Gabriel Fahrenheit is mentioned as a German physicist. However, according to the Encyclopedia Britannica, he was a Dutch physicist born in Gdansk, Poland on May 24, 1686. Fahrenheit himself made scientific instruments and in 1709 invented the alcohol thermometer, and in 1714 the mercury thermometer.

In 1724, Fahrenheit became a member of the Royal Society of London and presented his temperature scale to it. The scale was built on the basis of three reference points. In the original version (which was later changed), he took the temperature of the salt solution (ice, water and ammonium chloride in a ratio of 1:1:1) as the zero point. The temperature stabilization of this solution occurred at 0 °F (-17.78 °C). The second 32°F point was the melting point of the ice, i.e. temperature of a mixture of ice and water in a ratio of 1:1 (0 °C). The third point is normal temperature human body, to which he attributed 96 °F.

Why were such odd, non-circular numbers chosen? According to one story, Fahrenheit originally chose the most low temperature measured in his hometown Gdańsk in the winter of 1708/09. Later, when it became necessary to make this temperature well reproducible, he used saline to reproduce it. One explanation for the inaccuracy of the resulting temperature is that Fahrenheit did not have the ability to make a good brine solution to get the exact eutectic equilibrium composition of ammonium chloride (that is, he may have dissolved several salts, and not completely).

Another one interesting story associated with Fahrenheit's letter to his friend Herman Boerhaave. According to the letter, his scale was based on the work of astronomer Olof Römer, with whom Fahrenheit had previously interacted. In the Römer scale, saline solution freezes at zero degrees, water at 7.5 degrees, human body temperature is taken as 22.5 degrees and water boils at 60 degrees (it is believed that this is by analogy with 60 seconds in an hour). Fahrenheit multiplied each of the numbers by four to remove the fractional part. The melting point of ice turned out to be 30 deg. , and the human temperature is 90 degrees. He went further and shifted the scale so that the point of ice was 32 degrees and the temperature of the human body was 96 degrees. Thus, it became possible to divide the interval between these two points, which amounted to 64 degrees, by simply repeatedly dividing the interval in half. (64 is 2 to the sixth power).

Fahrenheit measured the boiling point of water with his calibrated thermometers at about 212°F. In the future, scientists decided to slightly redefine the scale, attributing exact value two well-reproducible reference points: the melting point of ice at 32°F and the boiling point of water at 212°F. At the same time, the normal temperature of a person on such a scale after new, more accurate measurements turned out to be about 98 ° F, and not 96 ° F.

The Fahrenheit scale has been around for 290 years. In English-speaking countries, it was a priority scale in industry, medicine and meteorology until the 60s of the 20th century. Subsequently, the countries of Europe switched to the Celsius scale. But there is still a special attachment to the Fahrenheit scale in the USA. Often children or housewives in America have no idea what an air temperature of 20 ° C is. Is it a lot or a little? Another thing is 68 ° F. Everything becomes clear to everyone. Therefore, the weather forecast in America always contains the temperature in degrees Fahrenheit.

British newspapers tend to report air temperatures in degrees Celsius, but provide a conversion table to degrees Fahrenheit. In the headlines of the British press, it is customary to indicate degrees Celsius for negative temperatures and Fahrenheit for positive ones. In February 2006 in the largest newspaper The Times An article was published on the psychology of perceiving weather forecasts, which stated that -6 ° C sounds colder to a person than 21 ° F, and 94 ° F sounds more impressive than 34 ° C.

Converting degrees Fahrenheit to degrees Celsius and vice versa is not a difficult task. Below for your convenience home page The site has an online temperature calculator that instantly converts degrees Fahrenheit to degrees Celsius.

countries, but in the late 1960s and early 1970s it was practically superseded by the Celsius scale. Only in Jamaica, the United States and Canada is the Fahrenheit scale still widely used for domestic purposes.

The scale is named after the German scientist Gabriel Fahrenheit, who proposed it in 1724.

On the Fahrenheit scale, the melting point of ice is +32°F and the boiling point of water is +212°F (at normal atmospheric pressure). In this case, one degree Fahrenheit is equal to 1/180 of the difference between these temperatures. The range 0°…+100° Fahrenheit roughly corresponds to the range −18°…+38° Celsius. Zero on this scale is determined by the freezing point of a mixture of water, ice and ammonia, and 100 ° F is taken as the normal temperature of the human body (however, Fahrenheit was mistaken in the last measurement: the normal temperature of the human body is 97.9 ° F). According to one version, for 100 degrees of the temperature scale, Fahrenheit took the body temperature of his wife, who at the time of measuring the temperature was unwell - this is precisely the reason for the shift of the centigrade point by 2.1 ° F, and not the measurement error itself.

Arithmetic conversions

One degree Fahrenheit equals 5/9 degrees Celsius, and Fahrenheit temperature is related to Celsius temperature by the following formulas.

From Celsius to Fahrenheit:

From Fahrenheit to Celsius:

Links

  • Converting temperature expressed in degrees Fahrenheit to other systems

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See what the "Fahrenheit scale" is in other dictionaries:

    FAHRENHEIT, a temperature scale based on the freezing point (32°F) and boiling point (212°F) of water. The interval between these points was divided into 180 equal parts. Although the Fahrenheit scale was later replaced by the Celsius scale, its ... ... Scientific and technical encyclopedic dictionary

    Fahrenheit- Farenheito skalė statusas T sritis Standartizacija ir metrologija apibrėžtis Temperatūros skalė, kurioje vandens virimo taškas atitinka 212 °F, o jo užšalimo taškas - 32 °F. atitikmenys: engl. Fahrenheit scale vok. Fahrenheits Skala, f rus. scale ... Penkiakalbis aiskinamasis metrologijos terminų žodynas