Story

The word "temperature" arose in those days when people believed that hotter bodies contained large quantity special substance - caloric, than in less heated ones. Therefore, temperature was perceived as the strength of a mixture of body matter and caloric. For this reason, the units of measurement for the strength of alcoholic beverages and temperature are called the same - degrees.

From the fact that temperature is kinetic energy molecules, it is clear that it is most natural to measure it in energy units (i.e. in the SI system in joules). However, temperature measurement began long before the creation of the molecular kinetic theory, so practical scales measure temperature in conventional units - degrees.

Kelvin scale

Thermodynamics uses the Kelvin scale, in which temperature is measured from absolute zero (the state corresponding to the minimum theoretically possible internal energy body), and one kelvin is equal to 1/273.16 of the distance from absolute zero to the triple point of water (the state in which ice, water and water vapor are in equilibrium). Boltzmann's constant is used to convert kelvins into energy units. Derived units are also used: kilokelvin, megakelvin, millikelvin, etc.

Celsius

In everyday life, the Celsius scale is used, in which 0 is the freezing point of water, and 100° is the boiling point of water at atmospheric pressure. Since the freezing and boiling points of water are not well defined, the Celsius scale is currently defined using the Kelvin scale: a degree Celsius is equal to a kelvin, absolute zero is taken to be −273.15 °C. The Celsius scale is practically very convenient because water is very common on our planet and our life is based on it. Zero Celsius is a special point for meteorology, since the freezing of atmospheric water significantly changes everything.

Fahrenheit

In England and especially in the USA, the Fahrenheit scale is used. In this scale, the interval from the temperature itself is divided into 100 degrees. cold winter in the city where Fahrenheit lived, to a temperature human body. Zero degrees Celsius is 32 degrees Fahrenheit, and a degree Fahrenheit is 5/9 degrees Celsius.

The currently accepted definition of the Fahrenheit scale is: temperature scale, 1 degree of which (1 °F) is equal to 1/180 of the difference between the boiling point of water and the melting point of ice at atmospheric pressure, and the melting point of ice is +32 °F. Fahrenheit temperature is related to Celsius temperature (t °C) by the ratio t °C = 5/9 (t °F - 32), that is, a change in temperature of 1 °F corresponds to a change of 5/9 °C. Proposed by G. Fahrenheit in 1724.

Reaumur scale

Proposed in 1730 by R. A. Reaumur, who described the alcohol thermometer he invented.

The unit is the degree Reaumur (°R), 1 °R is equal to 1/80 of the temperature interval between the reference points - the melting temperature of ice (0 °R) and the boiling point of water (80 °R)

1 °R = 1.25 °C.

Currently, the scale has fallen out of use; it survived longest in France, the author’s homeland.

Conversion of temperature between main scales
	Kelvin	Celsius	Fahrenheit
Kelvin (K)		C + 273.15	= (F + 459.67) / 1.8
Celsius (°C)	K − 273.15		= (F − 32) / 1.8
Fahrenheit (°F)	K 1.8 − 459.67	C 1.8 + 32

Comparison of temperature scales

Description	Kelvin	Celsius	Fahrenheit	Newton	Reaumur
Absolute zero		−273.15	−459.67	−90.14	−218.52
Melting temperature of a mixture of Fahrenheit (salt and ice in equal quantities)	255.37	−17.78		−5.87	−14.22
Freezing point of water (normal conditions)	273.15
Average human body temperature ¹	310.0	36.8	98.2	12.21	29.6
Boiling point of water (normal conditions)	373.15
Solar surface temperature	5800	5526	9980	1823	4421

¹ Normal human body temperature is 36.6 °C ±0.7 °C, or 98.2 °F ±1.3 °F. The commonly quoted value of 98.6 °F is an exact conversion to Fahrenheit of the 19th century German value of 37 °C. Since this value is not within the range of normal temperature according to modern concepts, we can say that it contains excessive (incorrect) accuracy. Some values ​​in this table have been rounded.

Comparison of Fahrenheit and Celsius scales

(o F- Fahrenheit scale, oC- Celsius scale)

oF	oC		oF	oC		oF	oC		oF	oC
459.67 -450 -400 -350 -300 -250 -200 -190 -180 -170 -160 -150 -140 -130 -120 -110 -100 -95 -90 -85 -80 -75 -70 -65	273.15 -267.8 -240.0 -212.2 -184.4 -156.7 -128.9 -123.3 -117.8 -112.2 -106.7 -101.1 -95.6 -90.0 -84.4 -78.9 -73.3 -70.6 -67.8 -65.0 -62.2 -59.4 -56.7 -53.9		60 -55 -50 -45 -40 -35 -30 -25 -20 -19 -18 -17 -16 -15 -14 -13 -12 -11 -10 -9 -8 -7 -6 -5	51.1 -48.3 -45.6 -42.8 -40.0 -37.2 -34.4 -31.7 -28.9 -28.3 -27.8 -27.2 -26.7 -26.1 -25.6 -25.0 -24.4 -23.9 -23.3 -22.8 -22.2 -21.7 -21.1 -20.6		4 -3 -2 -1 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19	20.0 -19.4 -18.9 -18.3 -17.8 -17.2 -16.7 -16.1 -15.6 -15.0 -14.4 -13.9 -13.3 -12.8 -12.2 -11.7 -11.1 -10.6 -10.0 -9.4 -8.9 -8.3 -7.8 -7.2		20 21 22 23 24 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 125 150 200	6.7 -6.1 -5.6 -5.0 -4.4 -3.9 -1.1 1.7 4.4 7.2 10.0 12.8 15.6 18.3 21.1 23.9 26.7 29.4 32.2 35.0 37.8 51.7 65.6 93.3

To convert degrees Celsius to Kelvin, you must use the formula T=t+T 0 where T is the temperature in kelvins, t is the temperature in degrees Celsius, T 0 =273.15 kelvins. The size of a degree Celsius is equal to Kelvin.

You've probably noticed more than once in American films that they measure temperature rather strangely. It’s strange for us, since we are used to the fact that we have this indicator in degrees Celsius. At zero, water freezes; at a hundred, it boils. Everything is simple and convenient. But to the typical American this will seem odd. After all, he will claim that water turns into ice at 32 degrees. But only in Fahrenheit. Of course, the temperature in Celsius and Fahrenheit will be very different. Let's figure out how much. Why did this happen and find out how to convert Fahrenheit to Celsius.

Fahrenheit or Celsius?

Throughout the world, it is customary to measure temperature in degrees Celsius (°C). Actually, this system is named after the Swedish scientist who developed a new scale in the 18th century. At first, he took the boiling point of water as zero, and freezing occurred at a hundred degrees. But then either he himself or someone else (it is not known for certain) revised the system and simply turned it upside down.

Since then, this scale has become the most widespread in the world, displacing various analogues. But one still firmly settled. In the US, we still talk about temperature in degrees Fahrenheit (°F). Other English-speaking countries and Europe abandoned this unit of measurement in the last century.

According to Fahrenheit, water boils at 212 degrees and freezes at 32. 100°F corresponds to the temperature of the human body, which is where he started from. True, if you convert one hundred degrees Fahrenheit to Celsius, you get a little more than 37 °C. Probably, at the time of the creation of the system, the scientist was sick with a fever.

Objectively, his system (also named after the scientist) is not very logical compared to Celsius, but it has the right to life.

How to convert Fahrenheit to Celsius?

You are unlikely to ever need this skill, but if you suddenly find yourself in the states or get behind the wheel of a purely American car, then it’s fine. To convert from one system to another, there is a formula for Fahrenheit to Celsius. It can, of course, be applied in the opposite direction.

To make the temperature in °F become °C, you need to subtract 32 from the original number, divide the difference by two and add one tenth to the resulting number.

For example, you came across an American thermometer. You took the temperature and it was 98 degrees Fahrenheit. In Celsius, this value will be as follows: 98 - 32 = 66 / 2 = 33 + 3.3 = 36.3 °C. This calculation is quite accurate, there is, of course, a small error, but for domestic needs this formula is quite acceptable.

How to convert Celsius to Fahrenheit?

Quite simple. We multiply the temperature in Celsius by 1.8 and add 32. For example, 100°C will be equal to 212°F, that is, 100 x 1.8 + 32. In general, some thermometers are produced with both scales on both sides, which instantly solves the issue and a person does not need to think about how to convert Fahrenheit to Celsius.

In addition, there are various online converters and applications for your phone, so there shouldn’t be any problems.

It is worth noting that none of the above temperature measurement scales are absolute. These are household systems, but in science, others are used for various studies, such as the Kelvin scale (K), for example, where zero is considered the lowest possible temperature at which a substance thermal energy it is impossible to extract (0K = −273.15 °C = −459.67 °F).

We all know very well that the air temperature inside and outside the room is measured on the Celsius scale. Many have also heard about the existence of the Fahrenheit scale, but not everyone knows what their differences are. In order to broaden your horizons and replenish your knowledge base, we will cover this issue in more detail.

Definition

Celsius– a temperature scale based on the freezing point of water (0 degrees) and its boiling point (100 degrees).

Fahrenheit– outdated temperature scale, lowest point which is the melting point of ammonia and a mixture of snow.

Comparison

Back in the 18th century, Daniel Fahrenheit set himself a goal: to create a temperature scale that was as convenient as possible for humans, without negative values. Therefore, for the lower mark, he chose the lowest temperature known at that time - the melting point of ammonia and a mixture of snow, designating it as zero degrees. The lowest point on the Celsius scale was the temperature at which ice melts and water freezes, and the highest point is its boiling point.

So, according to the Fahrenheit scale, the melting point of ice is at 32 degrees, and the boiling point of water is 212 degrees, provided normal atmospheric pressure. And one degree of this scale corresponds to 1/180 of the difference in these temperatures. The range from -18 to 38 degrees Celsius is equivalent to the range from 0 to 100 degrees Fahrenheit. To convert Celsius to Fahrenheit, multiply by 1.8 and add 32.

The degree Fahrenheit is an obsolete linear unit of temperature. For a long period of time it was actively used in English speaking countries, but in the 60-70s of the 20th century it was supplanted by the Celsius scale. Only in Belize and the USA is the Fahrenheit scale still found wide application for domestic purposes.

Conclusions website

1. The lowest point on the Fahrenheit scale is the melting point of ammonia and the snow mixture, while the lowest point on the Celsius scale is the melting point of ice and the freezing point of water.
2. The range from -18 to 38 degrees Celsius is equivalent to the range from 0 to 100 degrees Fahrenheit.
3. The Fahrenheit degree is an obsolete linear unit of temperature used today only in Belize and the United States for domestic purposes.

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Initial value

Converted value

kelvin degrees Celsius degrees Fahrenheit degrees Rankine degrees Reaumur Planck temperature

More about temperature

General information

Do you find it difficult to translate units of measurement from one language to another? Colleagues are ready to help you. Post a question in TCTerms and within a few minutes you will receive an answer.

Temperature in degrees Fahrenheit is not exotic now. It is very often indicated on many foreign instruments, especially on medical and meteorological thermometers. The Fahrenheit scale is the most popular temperature scale outside the SI system. We decided to dig a little into history and outline for the inquisitive readers of our portal the history of the creation of this very old, but still popular in some countries, temperature scale.

In many reference books, including Russian Wikipedia, Daniel Gabriel Fahrenheit is mentioned as a German physicist. However, according to the Encyclopedia Britannica, he was a Dutch physicist born in Poland in Gdansk 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 it with his temperature scale. The scale was constructed based on three reference points. In the original version (which was later changed), he took the temperature of the brine solution (ice, water and ammonium chloride in a ratio of 1:1:1) as the zero point. The temperature of this solution stabilized at 0 °F (-17.78 °C). The second point of 32°F was the melting point of 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 strange, non-round numbers chosen? According to one story, Fahrenheit initially chose the most low temperature, measured in his hometown of Gdansk in the winter of 1708/09. Later, when it became necessary to make this temperature well reproducible, he used to reproduce it brine. One explanation for the inaccuracy of the temperature obtained is that Fahrenheit did not have the ability to make a good brine solution to obtain an accurate eutectic equilibrium composition of ammonium chloride (that is, he may have dissolved several salts, and not completely).

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

When I measured the boiling point of water with my calibrated thermometers, the Fahrenheit value was about 212 °F. Subsequently, 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 this scale after new, more precise measurements it turned out to be about 98 °F, 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, European countries switched to the Celsius scale. But there is still a special attachment to the Fahrenheit scale in the United States. Often children or housewives in America have no idea what an air temperature of 20 °C is. Is it a lot or a little? 68°F is another matter. 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 also provide a conversion table to Fahrenheit. News headlines in the British press tend to indicate degrees Celsius for negative temperatures and Fahrenheit for the positive ones. In February 2006 in the largest newspaper The Times An article was published about the psychology of weather forecasting, 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 difficult. For your convenience, at the bottom of the main page of the site there is an online temperature calculator that instantly converts degrees Fahrenheit to degrees Celsius.