Celsius
degree Celsius | |
---|---|
SI | |
Unit of | temperature |
Symbol | °C |
Named after | Anders Celsius |
Conversions | |
x °C in ... | ... corresponds to ... |
°F |
The degree Celsius is the unit of
Throughout the 19th century, the scale was based on 0 °C for the freezing point of water and 100 °C for the boiling point of water at 1
Between 1954 and 2019, the precise definitions of the unit degree Celsius and the Celsius scale used absolute zero and the triple point of water. Since 2007, the Celsius scale has been defined in terms of the kelvin, the SI base unit of thermodynamic temperature (symbol: K). Absolute zero, the lowest temperature, is now defined as being exactly 0 K and −273.15 °C.[4]
History
In 1742, Swedish astronomer
In 1743, the
In 1744, coincident with the death of Anders Celsius, the Swedish botanist Carl Linnaeus (1707–1778) reversed Celsius's scale.[12] His custom-made "Linnaeus-thermometer", for use in his greenhouses, was made by Daniel Ekström, Sweden's leading maker of scientific instruments at the time, whose workshop was located in the basement of the Stockholm observatory. As often happened in this age before modern communications, numerous physicists, scientists, and instrument makers are credited with having independently developed this same scale;[13] among them were Pehr Elvius, the secretary of the Royal Swedish Academy of Sciences (which had an instrument workshop) and with whom Linnaeus had been corresponding; Daniel Ekström [sv], the instrument maker; and Mårten Strömer (1707–1770) who had studied astronomy under Anders Celsius.
The first known Swedish document
... since the caldarium (the hot part of the greenhouse) by the angle of the windows, merely from the rays of the sun, obtains such heat that the thermometer often reaches 30 degrees, although the keen gardener usually takes care not to let it rise to more than 20 to 25 degrees, and in winter not under 15 degrees ...
"Centigrade" versus "Celsius"
Since the 19th century, the scientific and
In the French language, the term centigrade also means one hundredth of a
While "Celsius" is commonly used in scientific work, "centigrade" remains commonly used in English-speaking countries, especially in informal contexts.[17]
While in Australia from 1 September 1972, only Celsius measurements were given for temperature in weather reports/forecasts,[18] it was not until February 1985 that the weather forecasts issued by the BBC switched from "centigrade" to "Celsius".[19]
Common temperatures
All phase transitions are at standard atmosphere. Figures are either by definition, or approximated from empirical measurements.
Kelvin (K) | Celsius (°C) | Fahrenheit (°F) | Rankine (°R) | |
---|---|---|---|---|
Absolute zero[A] | 0 | −273.15 | −459.67 | 0 |
Intersection of Celsius and Fahrenheit scales[A] | 233.15 | −40 | −40 | 419.67 |
Boiling point of water[b] | 373.1339 | 99.9839 | 211.971 | 671.6410 |
Boiling point of liquid nitrogen | 77.4 | −195.8[20] | −320.4 | 139.3 |
Melting point of ice[21] | 273.1499 | −0.0001 | 31.9998 | 491.6698 |
Sublimation point of dry ice | 195.1 | −78 | −108.4 | 351.2 |
Common room temperature[B][22] | 293 | 20 | 68 | 528 |
Average normal human body temperature[23]
|
310.15 | 37.0 | 98.6 | 558.27 |
Name and symbol typesetting
The "degree Celsius" has been the only
The general rule of the International Bureau of Weights and Measures (BIPM) is that the numerical value always precedes the unit, and a space is always used to separate the unit from the number, e.g. "30.2 °C" (not "30.2°C" or "30.2° C").[25] The only exceptions to this rule are for the unit symbols for degree, minute, and second for plane angle (°, ′, and ″, respectively), for which no space is left between the numerical value and the unit symbol.[26] Other languages, and various publishing houses, may follow different typographical rules.
Unicode character
Unicode provides the Celsius symbol at code point U+2103 ℃ DEGREE CELSIUS. However, this is a compatibility character provided for roundtrip compatibility with legacy encodings. It easily allows correct rendering for vertically written East Asian scripts, such as Chinese. The Unicode standard explicitly discourages the use of this character: "In normal use, it is better to represent degrees Celsius '°C' with a sequence of U+00B0 ° DEGREE SIGN + U+0043 C LATIN CAPITAL LETTER C, rather than U+2103 ℃ DEGREE CELSIUS. For searching, treat these two sequences as identical."[27]
Temperatures and intervals
The degree Celsius is subject to the same rules as the kelvin with regard to the use of its unit name and symbol. Thus, besides expressing specific temperatures along its scale (e.g. "Gallium melts at 29.7646 °C" and "The temperature outside is 23 degrees Celsius"), the degree Celsius is also suitable for expressing temperature intervals: differences between temperatures or their uncertainties (e.g. "The output of the heat exchanger is hotter by 40 degrees Celsius", and "Our standard uncertainty is ±3 °C").[28] Because of this dual usage, one must not rely upon the unit name or its symbol to denote that a quantity is a temperature interval; it must be unambiguous through context or explicit statement that the quantity is an interval.[c] This is sometimes solved by using the symbol °C (pronounced "degrees Celsius") for a temperature, and C° (pronounced "Celsius degrees") for a temperature interval, although this usage is non-standard.[29] Another way to express the same is "40 °C ± 3 K", which can be commonly found in literature.
Celsius measurement follows an
Coexistence with Kelvin
In science and in engineering, the Celsius and Kelvin scales are often used in combination in close contexts, e.g. "a measured value was 0.01023 °C with an uncertainty of 70 μK". This practice is permissible because the magnitude of the degree Celsius is equal to that of the kelvin. Notwithstanding the official endorsement provided by decision no. 3 of Resolution 3 of the 13th CGPM,
Melting and boiling points of water
from Celsius | to Celsius | |
---|---|---|
Fahrenheit | x °C ≘ (x × 9/5 + 32) °F | x °F ≘ (x − 32) × 5/9 °C |
Kelvin | x °C ≘ (x + 273.15) K | x K ≘ (x − 273.15) °C |
Rankine | x °C ≘ (x + 273.15) × 9/5 °R | x °R ≘ (x − 491.67) × 5/9 °C |
For temperature intervals rather than specific temperatures, 1 °C = 1 K = 9/5 °F = 9/5 °R Conversion between temperature scales |
The melting and boiling points of water are no longer part of the definition of the Celsius scale. In 1948, the definition was changed to use the
When the melting and boiling points of water ceased being part of the definition, they became measured quantities instead. This is also true of the triple point.
In 1948 when the 9th General Conference on Weights and Measures (
This boiling-point difference of 16.1 millikelvins between the Celsius scale's original definition and the previous one (based on absolute zero and the triple point) has little practical meaning in common daily applications because water's boiling point is very sensitive to variations in
See also
- Outline of metrology and measurement
- Comparison of temperature scales
- Degree of frost
- Thermodynamic temperature
Notes
- KiB) as well as Temperature (2nd Edition/1990/Academic Press/0125696817), the term Celsius in connection with the centigrade scale was not used whatsoever by the scientific or thermometry communities until after the CIPM and CGPM adopted the term in 1948. The BIPM was not even aware that "degree Celsius" was in sporadic, non-scientific use before that time. It is also noteworthy that the twelve-volume, 1933 edition of OED didn't even have a listing for the word Celsius (but did have listings for both centigrade and centesimal in the context of temperature measurement). The 1948 adoption of Celsius accomplished three objectives:
- All common temperature scales would have their units named after someone closely associated with them; namely, Kelvin, Celsius, Fahrenheit, Réaumur and Rankine.
- Notwithstanding the important contribution of Linnaeus who gave the Celsius scale its modern form, Celsius's name was the obvious choice because it began with the letter C. Thus, the symbol °C that for centuries had been used in association with the name centigrade could remain in use and would simultaneously inherit an intuitive association with the new name.
- The new name eliminated the ambiguity of the term "centigrade", freeing it to refer exclusively to the French-language name for the unit of angular measurement.
- ITS-90, which approximates the temperature to 99.974 °C
- MiB).
References
- ^ "Celsius temperature scale". Encyclopædia Britannica. Retrieved 19 February 2012.
Celsius temperature scale, also called centigrade temperature scale, scale based on 0 ° for the melting point of water and 100 ° for the boiling point of water at 1 atm pressure.
- ^ Helmenstine, Anne Marie (15 December 2014). "What Is the Difference Between Celsius and Centigrade?". Chemistry.about.com. About.com. Archived from the original on 2 April 2015. Retrieved 25 April 2020.
- ^ "Proceedings of the 42nd CIPM (1948), 1948, p. 88". Bureau International des Poids et Mesures. 1948. Retrieved 19 August 2023.
- ^ "SI brochure, section 2.1.1.5". International Bureau of Weights and Measures. Archived from the original on 26 September 2007. Retrieved 9 May 2008.
- ^ Celsius, Anders (1742) "Observationer om twänne beständiga grader på en thermometer" (Observations about two stable degrees on a thermometer), Kungliga Svenska Vetenskapsakademiens Handlingar (Proceedings of the Royal Swedish Academy of Sciences), 3: 171–180 and Fig. 1.
- ^ "Resolution 4 of the 10th meeting of the CGPM (1954)".
- Facts On File, Manhattan, New York City. p. 43.
- ISBN 978-1-4381-0951-0.
1743 Jean-Pierre Christin inverts the fixed points on Celsius' scale, to produce the scale used today.
- ^ Mercure de France (1743): MEMOIRE sur la dilatation du Mercure dans le Thermométre. Chaubert; Jean de Nully, Pissot, Duchesne, Paris. pp. 1609–1610.
- ^ Journal helvétique (1743): LION. Imprimerie des Journalistes, Neuchâtel. pp. 308–310.
- ^ Memoires pour L'Histoire des Sciences et des Beaux Arts (1743): DE LYON. Chaubert, París. pp. 2125–2128.
- ^ Citation: Uppsala University (Sweden), Linnaeus' thermometer
- ^ Citation for Christin of Lyons: Le Moyne College, Glossary, (Celsius scale); citation for Linnaeus's connection with Pehr Elvius and Daniel Ekström: Uppsala University (Sweden), Linnaeus' thermometer; general citation: The Uppsala Astronomical Observatory, History of the Celsius temperature scale Archived 22 July 2009 at the Wayback Machine
- ^ Citations: University of Wisconsin–Madison, Linnæus & his Garden and; Uppsala University, Linnaeus' thermometer
- ^ Comptes rendus des séances de la cinquième conférence générale des poids et mesures, réunie à Paris en 1913. Bureau international des poids et mesures. 1913. pp. 55, 57, 59. Retrieved 10 June 2021. p. 60:
...à la température de 20° centésimaux
- ^ "CIPM, 1948 and 9th CGPM, 1948". International Bureau of Weights and Measures. Archived from the original on 5 April 2021. Retrieved 9 May 2008.
- ^ "centigrade, adj. and n." Oxford English Dictionary. Oxford University Press. Retrieved 20 November 2011.
- ^ "Temperature and Pressure go Metric" (PDF). Commonwealth Bureau of Meteorology. 1 September 1972. Retrieved 16 February 2022.
- YouTube
- ^ Lide, D.R., ed. (1990–1991). Handbook of Chemistry and Physics. 71st ed. CRC Press. p. 4–22.
- ^ The ice point of purified water has been measured at 0.000089(10) degrees Celsius – see Magnum, B.W. (June 1995). "Reproducibility of the Temperature of the Ice Point in Routine Measurements" (PDF). NIST Technical Note. 1411. Archived from the original (PDF) on 10 July 2007. Retrieved 11 February 2007.
- ^ "SI Units – Temperature". NIST Office of Weights and Measures. 2010. Retrieved 21 July 2022.
- ^ Elert, Glenn (2005). "Temperature of a Healthy Human (Body Temperature)". The Physics Factbook. Retrieved 22 August 2007.
- National Institute of Standards and Technology (NIST). 2000. Archived from the originalon 11 November 2004. Retrieved 16 November 2011.
- ^ BIPM, SI Brochure, Section 5.3.3.
- BIPM's SI brochure: Subsection 5.3.3, Formatting the value of a quantity. Archived 5 July 2014 at the Wayback Machine
- ISBN 978-1-936213-13-9. Retrieved 20 April 2017.
- ^ Decision No. 3 of Resolution 3 of the 13th CGPM.
- ^ H.D. Young, R. A. Freedman (2008). University Physics with Modern Physics (12th ed.). Addison Wesley. p. 573.
- ^ This fact is demonstrated in the book Biostatistics: A Guide to Design, Analysis, and Discovery By Ronald N. Forthofer, Eun Sul Lee and Mike Hernandez
- ^ "Resolution 3 of the 13th CGPM (1967)".
- ^ "Resolution 3 of the 9th CGPM (1948)". International Bureau of Weights and Measures. Retrieved 6 February 2024.
- ^ Citation: London South Bank University, Water Structure and Behavior, notes c1 and c2
External links
The dictionary definition of Celsius at Wiktionary
- NIST, Basic unit definitions: Kelvin
- The Uppsala Astronomical Observatory, History of the Celsius temperature scale
- London South Bank University, Water, scientific data
- BIPM, SI brochure, section 2.1.1.5, Unit of thermodynamic temperature