9) on a Hot Day, the Thermometer Read 95 Ââ°f. What Is the Temperature in Degrees Celsius?

Scale and unit of measurement of measurement for temperature

degree Celsius
A thermometer calibrated in degrees Celsius
General information
Unit system	SI derived unit of measurement
Unit of	Temperature
Symbol	°C
Named after	Anders Celsius
Conversions
x °C in ...	... is equal to ...
K	10 + 273.fifteen
°F	9 / 5 (x) + 32

The degree Celsius is a unit of temperature on the Celsius scale,^[1] a temperature scale originally known as the centigrade scale.^[2] The degree Celsius (symbol: °C) can refer to a specific temperature on the Celsius calibration or a unit to indicate a difference or range between 2 temperatures. Information technology is named subsequently the Swedish astronomer Anders Celsius (1701–1744), who developed a like temperature scale in 1742. Before being renamed to honour Anders Celsius in 1948, the unit was called centigrade, from the Latin centum, which means 100, and gradus, which means steps. Most major countries use this scale; the other major scale, Fahrenheit, is still used in the United states of america, some island territories, and Liberia. The Kelvin scale is of use in the sciences, with 0 One thousand (-273.15 °C) representing absolute zero.

Since 1743 the Celsius scale has been based on 0 °C for the freezing point of h2o and 100 °C for the humid bespeak of h2o at ane atm pressure. Prior to 1743 the values were reversed (i.e. the boiling point was 0 degrees and the freezing point was 100 degrees). The 1743 scale reversal was proposed by Jean-Pierre Christin.

By international agreement, between 1954 and 2019 the unit of measurement degree Celsius and the Celsius scale were divers by absolute zero and the triple bespeak of water. Subsequently 2007, it was clarified that this definition referred to Vienna Standard Mean Ocean H2o (VSMOW), a precisely defined water standard.^[3] This definition also precisely related the Celsius scale to the Kelvin scale, which defines the SI base unit of thermodynamic temperature with symbol Thousand. Accented zero, the lowest temperature possible, is defined as being exactly 0 K and −273.15 °C. Until 19 May 2019, the temperature of the triple point of water was defined as exactly 273.sixteen Yard (0.01 °C).^[4] This ways that a temperature difference of one degree Celsius and that of i kelvin are exactly the aforementioned.^[five]

On 20 May 2019, the kelvin was redefined so that its value is now determined by the definition of the Boltzmann constant rather than beingness defined by the triple point of VSMOW. This means that the triple betoken is now a measured value, non a defined value. The newly-defined exact value of the Boltzmann constant was selected so that the measured value of the VSMOW triple point is exactly the same as the older defined value to within the limits of accuracy of contemporary metrology. The degree Celsius remains exactly equal to the kelvin, and 0 K remains exactly −273.15 °C.

History [edit]

An analogy of Anders Celsius's original thermometer. Note the reversed calibration, where 100 is the freezing point of water and 0 is its boiling betoken.

In 1742, Swedish astronomer Anders Celsius (1701–1744) created a temperature scale that was the reverse of the calibration now known equally "Celsius": 0 represented the boiling signal of h2o, while 100 represented the freezing point of water.^[6] In his paper Observations of 2 persistent degrees on a thermometer, he recounted his experiments showing that the melting signal of water ice is essentially unaffected by pressure. He as well determined with remarkable precision how the boiling point of water varied as a part of atmospheric pressure. He proposed that the zero betoken of his temperature calibration, being the humid point, would be calibrated at the mean barometric pressure at mean body of water level. This pressure level is known equally one standard atmosphere. The BIPM's 10th General Conference on Weights and Measures (CGPM) in 1954 defined one standard temper to equal precisely i,013,250 dynes per square centimeter (101.325 kPa).^[seven]

In 1743, the Lyonnais physicist Jean-Pierre Christin, permanent secretary of the Academy of Lyon, inverted the Celsius scale so that 0 represented the freezing point of water and 100 represented the humid signal of h2o. Some credit Christin for independently inventing the reverse of Celsius' original scale, while others believe Christin but reversed Celsius' calibration.^{[8] [9]} On nineteen May 1743 he published the design of a mercury thermometer, the "Thermometer of Lyon" built by the craftsman Pierre Casati that used this calibration.^{[10] [eleven] [12]}

In 1744, ancillary with the death of Anders Celsius, the Swedish botanist Carl Linnaeus (1707–1778) reversed Celsius's calibration.^[13] His custom-made "linnaeus-thermometer", for use in his greenhouses, was fabricated by Daniel Ekström, Sweden's leading maker of scientific instruments at the fourth dimension, whose workshop was located in the basement of the Stockholm observatory. As frequently happened in this age before modern communications, numerous physicists, scientists, and instrument makers are credited with having independently developed this same calibration;^[14] among them were Pehr Elvius, the secretarial assistant of the Imperial 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 nether Anders Celsius.

The first known Swedish document^[xv] reporting temperatures in this modern "forward" Celsius scale is the paper Hortus Upsaliensis dated 16 Dec 1745 that Linnaeus wrote to a student of his, Samuel Nauclér. In information technology, Linnaeus recounted the temperatures inside the orangery at the University of Uppsala Botanical Garden:

...since the caldarium (the hot part of the greenhouse) by the angle of the windows, only from the rays of the sun, obtains such rut that the thermometer oftentimes reaches thirty degrees, although the neat gardener usually takes care not to permit it rise to more than 20 to 25 degrees, and in winter not nether 15 degrees...

Centigrade vis-à-vis Celsius [edit]

 Countries that employ both Fahrenheit (°F) and Celsius (°C).

 Countries that utilise Celsius (°C).

Since the 19th century, the scientific and thermometry communities worldwide take used the phrase "centigrade calibration" and temperatures were often reported but every bit "degrees" or, when greater specificity was desired, as "degrees centigrade", with the symbol °C.

In the French language, the term centigrade also means 1 hundredth of a gradian, when used for athwart measurement. The term centesimal degree was later on introduced for temperatures^[16] but was also problematic, as it means gradian (one hundredth of a correct bending) in the French and Spanish languages. The risk of confusion between temperature and athwart measurement was eliminated in 1948 when the 9th coming together of the General Conference on Weights and Measures and the Comité International des Poids et Mesures (CIPM) formally adopted "degree Celsius" for temperature.^{[17] [a]}

While "Celsius" is the term commonly used in scientific work, "centigrade" remains in common use in English-speaking countries, especially in breezy contexts.^[18]

While in Commonwealth of australia from 1 September 1972, only Celsius measurements were given for temperature in conditions reports/forecasts,^[19] information technology was not until February 1985 that the weather forecasts issued past the BBC switched from "centigrade" to "Celsius".^[20]

Common temperatures [edit]

Some primal temperatures relating the Celsius scale to other temperature scales are shown in the table below.

Key scale relations

	Kelvin	Celsius	Fahrenheit	Rankine
Absolute zero (exactly)	0 K	−273.xv °C	−459.67 °F	0 °R
Boiling signal of liquid nitrogen	77.4 K	−195.8 °C[21]	−320.four °F	139.3 °R
Sublimation point of dry ice	195.1 K	−78 °C	−108.4 °F	351.two °R
Intersection of Celsius and Fahrenheit scales	233.15 Grand	−40 °C	−40 °F	419.67 °R
Melting point of H2O (purified water ice)[22]	273.1499 K	−0.0001 °C	31.9998 °F	491.6698 °R
Room temperature (NIST standard)[23]	293.xv K	20.0 °C	68.0 °F	527.69 °R
Normal homo body temperature (boilerplate)[24]	310.15 Chiliad	37.0 °C	98.half dozen °F	558.27 °R
H2o's humid point at 1 atm (101.325 kPa) (estimate: see Humid point)[b]	373.1339 G	99.9839 °C	211.971 °F	671.6410 °R

Name and symbol typesetting [edit]

The "degree Celsius" has been the only SI unit whose total unit proper name contains an capital letter letter since 1967, when the SI base unit for temperature became the kelvin, replacing the capitalized term degrees Kelvin. The plural class is "degrees Celsius".^[25]

The full general rule of the International Bureau of Weights and Measures (BIPM) is that the numerical value e'er precedes the unit, and a infinite is always used to separate the unit from the number, due east.g. "30.2 °C" (non "xxx.2°C" or "30.ii° C").^[26] The merely exceptions to this dominion are for the unit of measurement symbols for degree, minute, and second for aeroplane bending (°, ′, and ″, respectively), for which no infinite is left between the numerical value and the unit of measurement symbol.^[27] Other languages, and diverse publishing houses, may follow dissimilar typographical rules.

Unicode character [edit]

Unicode provides the Celsius symbol at code point U+2103 ℃ Caste CELSIUS. However, this is a compatibility graphic symbol 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 grapheme: "In normal use, it is amend 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, care for these ii sequences as identical."^[28]

Temperatures and intervals [edit]

The caste Celsius is field of study to the same rules as the kelvin with regard to the use of its unit proper name and symbol. Thus, besides expressing specific temperatures along its scale (due east.g. "Gallium melts at 29.7646 °C" and "The temperature exterior is 23 degrees Celsius"), the degree Celsius is also suitable for expressing temperature intervals: differences between temperatures or their uncertainties (e.chiliad. "The output of the heat exchanger is hotter past 40 degrees Celsius", and "Our standard doubt is ±three °C").^[29] 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 past 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.^[30] Some other way to express the same is "40 °C ± 3 K", which can be commonly institute in literature.

Celsius measurement follows an interval system merely not a ratio arrangement; and it follows a relative scale not an absolute scale. For example, an object at twenty °C does not have twice the energy of when it is x °C; and 0 °C is non the lowest Celsius value. Thus, degrees Celsius is a useful interval measurement but does not possess the characteristics of ratio measures like weight or distance.^[31]

Coexistence of Kelvin and Celsius scales [edit]

In science and in engineering, the Celsius scale and the Kelvin scale are often used in combination in close contexts, e.yard. "a measured value was 0.01023 °C with an uncertainty of 70 μK". This practice is permissible because the magnitude of the caste Celsius is equal to that of the kelvin. Withal the official endorsement provided by decision no. 3 of Resolution 3 of the 13th CGPM,^[32] which stated "a temperature interval may besides exist expressed in degrees Celsius", the practise of simultaneously using both °C and G remains widespread throughout the scientific globe equally the utilise of SI-prefixed forms of the degree Celsius (such as "μ°C" or "microdegrees Celsius") to express a temperature interval has not been well adopted.

Melting and boiling points of water [edit]

Celsius temperature conversion formulae

	from Celsius	to Celsius
Fahrenheit	[°F] = [°C] × nine⁄5  + 32	[°C] = ([°F] − 32) × five⁄ix
Kelvin	[K] = [°C] + 273.15	[°C] = [Thousand] − 273.fifteen
Rankine	[°R] = ([°C] + 273.15) × nine⁄5	[°C] = ([°R] − 491.67) × 5⁄9
For temperature intervals rather than specific temperatures, 1 °C = 1 K = 9⁄5  °F = 9⁄5  °R Comparisons among diverse temperature scales

The melting and boiling points of h2o are no longer part of the definition of the Celsius scale. In 1948, the definition was changed to use the triple point of water.^[33] In 2005 the definition was further refined to utilise h2o with precisely divers isotopic composition (VSMOW) for the triple betoken. In 2019, the definition was inverse to utilize the Boltzmann constant, completely decoupling the definition of the kelvin from the properties of water. Each of these formal definitions left the numerical values of the Celsius scale identical to the prior definition to inside the limits of accurateness of the metrology of the time.

When the melting and humid points of h2o ceased being part of the definition, they became measured quantities instead. This is also true of the triple point.

In 1948 when the 9th Full general Briefing on Weights and Measures (CGPM) in Resolution 3 outset considered using the triple point of water as a defining point, the triple point was so shut to existence 0.01 °C greater than h2o's known melting indicate, it was simply defined equally precisely 0.01 °C. However, later measurements showed that the difference between the triple and melting points of VSMOW is really very slightly (<0.001 °C) greater than 0.01 °C. Thus, the actual melting point of ice is very slightly (less than a thousandth of a degree) below 0 °C. Also, defining water'due south triple point at 273.16 G precisely defined the magnitude of each 1 °C increment in terms of the absolute thermodynamic temperature calibration (referencing absolute zero). Now decoupled from the actual boiling indicate of water, the value "100 °C" is hotter than 0 °C – in absolute terms – past a factor of precisely 373.15 / 273.15 (approximately 36.61% thermodynamically hotter). When adhering strictly to the two-point definition for calibration, the boiling betoken of VSMOW under 1 standard atmosphere of pressure was actually 373.1339 Thousand (99.9839 °C). When calibrated to ITS-90 (a calibration standard comprising many definition points and ordinarily used for high-precision instrumentation), the boiling point of VSMOW was slightly less, well-nigh 99.974 °C.^[34]

This boiling-bespeak difference of 16.1 millikelvins between the Celsius scale's original definition and the previous i (based on absolute zero and the triple point) has fiddling applied meaning in common daily applications considering water's boiling indicate is very sensitive to variations in barometric force per unit area. For example, an distance modify of simply 28 cm (11 in) causes the boiling point to change by ane millikelvin.

See also [edit]

• Comparison of temperature scales
• Degree of frost
• ITS-90
• Réaumur scale
• Thermodynamic temperature

Notes [edit]

1. ^ Co-ordinate to The Oxford English Lexicon (OED), the term "Celsius' thermometer" had been used at to the lowest degree equally early as 1797. Further, the term "The Celsius or Centigrade thermometer" was again used in reference to a particular type of thermometer at least every bit early every bit 1850. The OED besides cites this 1928 reporting of a temperature: "My altitude was well-nigh 5,800 metres, the temperature was 28° Celsius." Still, dictionaries seek to find the earliest use of a discussion or term and are not a useful resources as regards to the terminology used throughout the history of scientific discipline. According to several writings of Dr. Terry Quinn CBE FRS, Director of the BIPM (1988–2004), including "Temperature Scales from the early days of thermometry to the 21st century" (PDF). Archived from the original (PDF) on 26 Dec 2010. Retrieved 31 May 2016. (146 KiB) besides equally Temperature (2nd Edition/1990/Academic Press/0125696817), the term Celsius in connection with the centigrade calibration was non used whatsoever by the scientific or thermometry communities until later on the CIPM and CGPM adopted the term in 1948. The BIPM was not even aware that "degree Celsius" was in sporadic, non-scientific employ before that time. It is also noteworthy that the twelve-volume, 1933 edition of OED didn't fifty-fifty have a listing for the word Celsius (just did have listings for both centigrade and centesimal in the context of temperature measurement). The 1948 adoption of Celsius achieved 3 objectives:

   ane.    All mutual temperature scales would accept their units named later someone closely associated with them; namely, Kelvin, Celsius, Fahrenheit, Réaumur and Rankine.

   2.    However the important contribution of Linnaeus who gave the Celsius scale its modern form, Celsius'due south proper name was the obvious option because it began with the letter of the alphabet C. Thus, the symbol °C that for centuries had been used in association with the name centigrade could remain in employ and would simultaneously inherit an intuitive association with the new name.

   3.    The new name eliminated the ambiguity of the term "centigrade", freeing information technology to refer exclusively to the French-linguistic communication name for the unit of angular measurement.

2. ^ For Vienna Standard Hateful Ocean H2o at one standard atmosphere (101.325 kPa) when calibrated solely per the ii-betoken definition of thermodynamic temperature. Older definitions of the Celsius scale once defined the boiling point of water under 1 standard atmosphere as being precisely 100 °C. However, the current definition results in a boiling bespeak that is actually 16.1 mK less. For more virtually the actual humid point of water, see VSMOW in temperature measurement. A different approximation uses ITS-90, which approximates the temperature to 99.974 °C
3. ^ In 1948, Resolution vii of the ninth CGPM stated, "To betoken a temperature interval or difference, rather than a temperature, the give-and-take 'degree' in full, or the abbreviation 'deg' must be used." This resolution was abrogated in 1967/1968 by Resolution iii of the 13th CGPM, which stated that ["The names "degree Kelvin" and "caste", the symbols "°K" and "deg" and the rules for their use given in Resolution 7 of the ninth CGPM (1948),] ...and the designation of the unit to express an interval or a difference of temperatures are abrogated, simply the usages which derive from these decisions remain permissible for the time existence." Consequently, there is now wide freedom in usage regarding how to point a temperature interval. The nigh important matter is that ane'due south intention must be articulate and the basic rule of the SI must be followed; namely that the unit name or its symbol must not be relied upon to indicate the nature of the quantity. Thus, if a temperature interval is, say, 10 Thousand or ten °C (which may be written 10 kelvins or 10 degrees Celsius), it must be unambiguous through obvious context or explicit statement that the quantity is an interval. Rules governing the expressing of temperatures and intervals are covered in the BIPM's "SI Brochure, 8th edition" (PDF). (1.39 MiB).

References [edit]

1. ^ "Celsius temperature scale". Encyclopædia Britannica . Retrieved 19 Feb 2012. Celsius temperature scale, also called centigrade temperature scale, calibration based on 0 ° for the melting bespeak of water and 100 ° for the boiling point of water at i atm force per unit area.
2. ^ Helmenstine, Anne Marie (15 December 2014). "What Is the Departure Between Celsius and Centigrade?". Chemical science.about.com. About.com. Retrieved 25 April 2020.
3. ^ "Resolution x of the 23rd CGPM (2007)". Retrieved 27 December 2021.
4. ^ "SI brochure, department 2.1.1.5". International Bureau of Weights and Measures. Archived from the original on 26 September 2007. Retrieved ix May 2008.
5. ^ "Essentials of the SI: Base of operations & derived units". Retrieved 9 May 2008.
6. ^ 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 Regal Swedish University of Sciences), iii : 171–180 and Fig. 1.
7. ^ "Resolution 4 of the 10th coming together of the CGPM (1954)".
8. ^ Don Rittner; Ronald A. Bailey (2005): Encyclopedia of Chemistry. Facts On File, Manhattan, New York Urban center. p. 43.
9. ^ Smith, Jacqueline (2009). "Appendix I: Chronology". The Facts on File Dictionary of Atmospheric condition and Climate. Infobase Publishing. p. 246. ISBN978-1-4381-0951-0. 1743 Jean-Pierre Christin inverts the fixed points on Celsius' scale, to produce the scale used today.
10. ^ Mercure de French republic (1743): MEMOIRE sur la dilatation du Mercure dans le Thermométre. Chaubert; Jean de Nully, Pissot, Duchesne, Paris. pp. 1609–1610.
11. ^ Journal helvétique (1743): Lion. Imprimerie des Journalistes, Neuchâtel. pp. 308–310.
12. ^ Memoires pour Fifty'Histoire des Sciences et des Beaux Arts (1743): DE LYON. Chaubert, París. pp. 2125–2128.
13. ^ Citation: Uppsala Academy (Sweden), Linnaeus' thermometer
14. ^ Citation for Daniel Ekström, Mårten Strömer, Christin of Lyons: The Physics Hypertextbook, Temperature; commendation for Christin of Lyons: Le Moyne College, Glossary, (Celsius scale); citation for Linnaeus'south connection with Pehr Elvius and Daniel Ekström: Uppsala University (Sweden), Linnaeus' thermometer; full general citation: The Uppsala Astronomical Observatory, History of the Celsius temperature scale
15. ^ Citations: Academy of Wisconsin–Madison, Linnæus & his Garden and; Uppsala Academy, Linnaeus' thermometer
16. ^ 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
17. ^ "CIPM, 1948 and 9th CGPM, 1948". International Bureau of Weights and Measures. Archived from the original on five Apr 2021. Retrieved 9 May 2008.
18. ^ "centigrade, adj. and due north." Oxford English Dictionary. Oxford University Press. Retrieved 20 Nov 2011.
19. ^ "Temperature and Pressure level become Metric" (PDF). Commonwealth Bureau of Meteorology. 1 September 1972. Retrieved 16 February 2022.
20. ^ 1985 BBC Special: A Change In The Weather on YouTube
21. ^ Lide, D.R., ed. (1990–1991). Handbook of Chemistry and Physics. 71st ed. CRC Press. p. 4–22.
22. ^ The ice point of purified water has been measured at 0.000089(10) degrees Celsius – run into Magnum, B.Westward. (June 1995). "Reproducibility of the Temperature of the Ice Point in Routine Measurements" (PDF). Nist Technical Annotation. 1411. Archived from the original (PDF) on 14 July 2007. Retrieved 11 Feb 2007.
23. ^ "SI Units – Temperature". 2010. Retrieved 7 November 2019.
24. ^ Elert, Glenn (2005). "Temperature of a Good for you Man (Body Temperature)". The Physics Factbook . Retrieved 22 August 2007.
25. ^ "Unit of thermodynamic temperature (kelvin)". The NIST Reference on Constants, Units, and Dubiousness: Historical context of the SI. National Constitute of Standards and Technology (NIST). 2000. Archived from the original on xi November 2004. Retrieved sixteen Nov 2011.
26. ^ BIPM, SI Brochure, Section 5.3.3.
27. ^ For more data on conventions used in technical writing, run across the informative SI Unit rules and mode conventions by the NIST as well as the BIPM's SI brochure: Subsection 5.three.3, Formatting the value of a quantity. Archived 5 July 2014 at the Wayback Machine
28. ^ "22.2". The Unicode Standard, Version 9.0 (PDF). Mountain View, CA, USA: The Unicode Consortium. July 2016. ISBN978-1-936213-13-9 . Retrieved twenty April 2017.
29. ^ Determination No. 3 of Resolution 3 of the 13th CGPM.
30. ^ H.D. Young, R. A. Freedman (2008). University Physics with Mod Physics (12th ed.). Addison Wesley. p. 573.
31. ^ 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
32. ^ "Resolution three of the 13th CGPM (1967)".
33. ^ "Resolution 3 of the 9th CGPM (1948)". International Bureau of Weights and Measures. Retrieved 9 May 2008.
34. ^ Commendation: London South Bank University, Water Construction and Behavior, notes c1 and c2

External links [edit]

The dictionary definition of Celsius at Wiktionary

• NIST, Bones unit of measurement definitions: Kelvin
• The Uppsala Astronomical Observatory, History of the Celsius temperature scale
• London Due south Bank University, Water, scientific information
• BIPM, SI brochure, section 2.one.1.5, Unit of measurement of thermodynamic temperature
• TAMPILE, Comparison of temperature scales

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Source: https://en.wikipedia.org/wiki/Celsius

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