Which of the Following Conditions is Unaffected by Physical Activity

Scale and unit of measurement of measurement for temperature

caste Celsius
A thermometer calibrated in degrees Celsius
General data
Unit system	SI
Unit of	Temperature
Symbol	°C
Named after	Anders Celsius
Conversions
x  °C in …	… is equal to …
SI base units	x + 273.xv M
Regal/The states units	nine / 5 x + 32 °F

The
degree Celsius
is the unit of temperature on the
Celsius scale,^[1]
(originally known as the
centigrade calibration),^[2]
one of ii temperature scales used in the International System of Units (SI), aslope the Kelvin scale. The caste Celsius (symbol:
°C) tin can refer to a specific temperature on the Celsius scale or a unit to bespeak a difference or range between two temperatures. Information technology is named after the Swedish astronomer Anders Celsius (1701–1744), who developed a similar temperature scale in 1742. Before being renamed to honour Anders Celsius in 1948, the unit was called
centigrade, from the Latin
centum, which ways 100, and
gradus, which means steps. Almost major countries use this scale; the other major calibration, Fahrenheit, is nonetheless used in the United States, some isle territories, and Liberia. The Kelvin scale is of use in the sciences, with 0 K (−273.xv °C) representing accented zero.

Since 1743 the Celsius scale has been based on 0 °C for the freezing point of h2o and 100 °C for the boiling point of water at 1 atm pressure. Prior to 1743 the values were reversed (i.due east. the boiling point was 0 degrees and the freezing point was 100 degrees). The 1743 scale reversal was proposed past Jean-Pierre Christin.

By international agreement, between 1954 and 2019 the unit of measurement
degree Celsius
and the Celsius scale were divers past absolute zippo and the triple indicate of water. Afterward 2007, it was clarified that this definition referred to Vienna Standard Mean Ocean Water (VSMOW), a precisely defined h2o standard.^[three]
This definition also precisely related the Celsius scale to the scale of the Kelvin, the SI base of operations unit of thermodynamic temperature with symbol K. Absolute zero, the lowest temperature possible, is divers as being exactly 0 K and −273.15 °C. Until nineteen May 2019, the temperature of the triple point of water was defined equally exactly 273.sixteen K (0.01 °C).^[4]

On twenty May 2019, the kelvin was redefined and so that its value is now determined past the definition of the Boltzmann constant rather than being defined past the triple point of VSMOW. This means that the triple betoken is now a measured value, non a defined value. The newly-defined verbal 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 gimmicky metrology. The temperature in degree Celsius is now defined every bit the temperature in kelvins subtracted by 273.xv,^[5]
[6]
meaning that a temperature departure of one caste Celsius and that of 1 kelvin are exactly the aforementioned,^[7]
and that the degree Celsius remains exactly equal to the kelvin (i.e., 0 °C remains exactly 273.15 K).

History

[edit]

In 1742, Swedish astronomer Anders Celsius (1701–1744) created a temperature calibration that was the contrary of the scale at present known as “Celsius”: 0 represented the boiling indicate of h2o, while 100 represented the freezing point of water.^[8]
In his newspaper
Observations of two persistent degrees on a thermometer, he recounted his experiments showing that the melting point of ice is essentially unaffected by pressure. He likewise determined with remarkable precision how the humid point of water varied as a role of atmospheric pressure. He proposed that the zero signal of his temperature scale, being the boiling point, would be calibrated at the mean barometric pressure at mean ocean level. This pressure level is known equally one standard atmosphere. The BIPM’s tenth General Conference on Weights and Measures (CGPM) in 1954 defined one standard temper to equal precisely one,013,250 dynes per square centimeter (101.325 kPa).^[9]

In 1743, the Lyonnais physicist Jean-Pierre Christin, permanent secretary of the Academy of Lyon, inverted the Celsius scale and so that 0 represented the freezing point of h2o and 100 represented the boiling betoken of water. Some credit Christin for independently inventing the reverse of Celsius’ original scale, while others believe Christin simply reversed Celsius’ calibration.^[10]
[xi]
On 19 May 1743 he published the blueprint of a mercury thermometer, the “Thermometer of Lyon” congenital by the craftsman Pierre Casati that used this scale.^{[12]
[xiii]
[14]}

In 1744, coincident with the death of Anders Celsius, the Swedish botanist Carl Linnaeus (1707–1778) reversed Celsius’due south scale.^[15]
His custom-made “linnaeus-thermometer”, for apply in his greenhouses, was made past Daniel Ekström, Sweden’southward leading maker of scientific instruments at the time, whose workshop was located in the basement of the Stockholm observatory. Equally frequently happened in this historic period before modern communications, numerous physicists, scientists, and instrument makers are credited with having independently adult this same scale;^[xvi]
amid 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^[17]
reporting temperatures in this mod “forward” Celsius scale is the newspaper
Hortus Upsaliensis
dated xvi December 1745 that Linnaeus wrote to a pupil of his, Samuel Nauclér. In it, 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, merely from the rays of the sun, obtains such rut that the thermometer often reaches 30 degrees, although the neat gardener normally takes care not to let information technology rise to more than 20 to 25 degrees, and in wintertime not under 15 degrees…

Centigrade vis-à-vis Celsius

[edit]

Since the 19th century, the scientific and thermometry communities worldwide have used the phrase “centigrade scale” and temperatures were often reported simply 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 i hundredth of a gradian, when used for angular measurement. The term
centesimal caste
was later introduced for temperatures^[18]
just was as well problematic, as it means gradian (ane hundredth of a right bending) in the French and Spanish languages. The hazard of confusion betwixt temperature and athwart measurement was eliminated in 1948 when the 9th meeting of the General Conference on Weights and Measures and the Comité International des Poids et Mesures (CIPM) formally adopted “degree Celsius” for temperature.^[19]
[a]

While “Celsius” is the term commonly used in scientific work, “centigrade” remains in common use in English language-speaking countries, particularly in informal contexts.^[xx]

While in Commonwealth of australia from 1 September 1972, simply Celsius measurements were given for temperature in weather reports/forecasts,^[21]
it was not until February 1985 that the weather forecasts issued by the BBC switched from “centigrade” to “Celsius”.^[22]

Common temperatures

[edit]

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

Cardinal scale relations

	Kelvin	Celsius	Fahrenheit	Rankine
Absolute nothing (exactly)	0 Thousand	−273.15 °C	−459.67 °F	0 °R
Humid point of liquid nitrogen	77.4 K	−195.8 °C[23]	−320.4 °F	139.3 °R
Sublimation point of dry out ice	195.i K	−78 °C	−108.4 °F	351.two °R
Intersection of Celsius and Fahrenheit scales	233.15 K	−40 °C	−40 °F	419.67 °R
Melting indicate of H2O (purified ice)[24]	273.1499 M	−0.0001 °C	31.9998 °F	491.6698 °R
Room temperature (NIST standard)[25]	293.15 Chiliad	20.0 °C	68.0 °F	527.69 °R
Normal human body temperature (average)[26]	310.xv K	37.0 °C	98.6 °F	558.27 °R
Water’s boiling point at ane atm (101.325 kPa) (guess: see Humid point)[b]	373.1339 K	99.9839 °C	211.971 °F	671.6410 °R

Proper name and symbol typesetting

[edit]

The “degree Celsius” has been the just SI unit whose full unit of measurement name contains an uppercase letter since 1967, when the SI base unit for temperature became the kelvin, replacing the capitalized term
degrees Kelvin. The plural form is “degrees Celsius”.^[27]

The full general rule of the International Agency of Weights and Measures (BIPM) is that the numerical value ever precedes the unit, and a space is always used to separate the unit from the number,
e.grand. “xxx.2 °C”
(not “30.2°C” or “30.2° C”).^[28]
The only exceptions to this rule are for the unit symbols for degree, minute, and second for plane bending (°, ′, and ″, respectively), for which no space is left betwixt the numerical value and the unit symbol.^[29]
Other languages, and various publishing houses, may follow dissimilar typographical rules.

Unicode character

[edit]

Unicode provides the Celsius symbol at code signal

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 E Asian scripts, such as Chinese. The Unicode standard explicitly discourages the employ of this character: “In normal use, it is improve 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 two sequences as identical.”^[30]

Temperatures and intervals

[edit]

The degree Celsius is subject field to the aforementioned rules as the kelvin with regard to the use of its unit name and symbol. Thus, besides expressing specific temperatures along its scale (e.1000. “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 past 40 degrees Celsius”, and “Our standard uncertainty is ±3 °C”).^[31]
Considering of this dual usage, i must non rely upon the unit name or its symbol to announce that a quantity is a temperature interval; information technology must be unambiguous through context or explicit argument 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.^[32]
Another style to express the same is
“twoscore °C ± 3 Thousand”, which tin be commonly constitute in literature.

Celsius measurement follows an interval system merely not a ratio organization; and information technology follows a relative scale non an accented scale. For example, an object at twenty °C does not accept twice the energy of when it is 10 °C; and 0 °C is non the everyman Celsius value. Thus, degrees Celsius is a useful interval measurement simply does non possess the characteristics of ratio measures like weight or distance.^[33]

Coexistence of Kelvin and Celsius scales

[edit]

In scientific discipline and in engineering science, the Celsius calibration and the Kelvin scale are often used in combination in close contexts, e.1000. “a measured value was 0.01023 °C with an uncertainty of seventy μK”. This exercise is permissible considering the magnitude of the degree Celsius is equal to that of the kelvin. Yet the official endorsement provided past conclusion no. 3 of Resolution 3 of the 13th CGPM,^[34]
which stated “a temperature interval may also be expressed in degrees Celsius”, the practice of simultaneously using both °C and K remains widespread throughout the scientific earth as the employ of SI-prefixed forms of the degree Celsius (such equally “μ°C” or “microdegrees Celsius”) to express a temperature interval has not been well adopted.

Melting and humid points of water

[edit]

Celsius temperature conversion formulae

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

The melting and humid points of water are no longer role of the definition of the Celsius scale. In 1948, the definition was changed to use the triple point of water.^[35]
In 2005 the definition was further refined to use water with precisely divers isotopic composition (VSMOW) for the triple point. In 2019, the definition was changed to use the Boltzmann abiding, 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 within the limits of accuracy of the metrology of the time.

When the melting and boiling points of h2o ceased existence function of the definition, they became measured quantities instead. This is as well true of the triple point.

In 1948 when the 9th Full general Conference on Weights and Measures (CGPM) in Resolution 3 commencement considered using the triple signal of water as a defining point, the triple betoken was so close to beingness 0.01 °C greater than h2o’due south known melting point, information technology was but defined as precisely 0.01 °C. However, later measurements showed that the difference betwixt the triple and melting points of VSMOW is actually very slightly (<0.001 °C) greater than 0.01 °C. Thus, the actual melting signal of ice is very slightly (less than a thousandth of a degree) below 0 °C. Also, defining water’southward triple point at 273.16 K precisely defined the magnitude of each ane °C increment in terms of the absolute thermodynamic temperature calibration (referencing absolute zero). Now decoupled from the actual boiling point of water, the value “100 °C” is hotter than 0 °C – in absolute terms – by 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 point of VSMOW under one standard atmosphere of pressure level was really 373.1339 Chiliad (99.9839 °C). When calibrated to ITS-90 (a calibration standard comprising many definition points and unremarkably used for high-precision instrumentation), the boiling bespeak of VSMOW was slightly less, near 99.974 °C.^[36]

This boiling-point difference of 16.one millikelvins betwixt the Celsius calibration’south original definition and the previous 1 (based on absolute zero and the triple point) has little applied meaning in common daily applications because water’s boiling signal is very sensitive to variations in barometric pressure level. For case, an altitude change of only 28 cm (xi in) causes the boiling signal to modify by one millikelvin.

See also

[edit]

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

Notes

[edit]

References

[edit]

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 South Bank University,
  H2o, scientific data
• BIPM,
  SI brochure, section 2.i.1.5, Unit of measurement of thermodynamic temperature
• TAMPILE,
  Comparison of temperature scales