View source for Degree (temperature)

{{Other uses|Degree (disambiguation)}}
{{Short description|Term used in defining several scales of temperature}}
{{Use dmy dates|date=July 2023|cs1-dates=y}}
{{Use list-defined references|date=July 2023}}
The term '''''degree''''' is used in several [[scales of temperature]], with the notable exception of [[kelvin]], primary unit of temperature for [[engineering]] and the [[physical sciences]]. The [[degree symbol]] '''°''' is usually used, followed by the initial letter of the unit; for example, "°C" for degree Celsius. A degree can be defined as a set change in temperature measured against a given scale; for example, one degree Celsius is one-hundredth of the temperature change between the point at which water starts to change state from solid to liquid state and the point at which it starts to change from its liquid to gaseous state.

==Scales of temperature measured in degrees==
Common scales of temperature measured in degrees:
* [[Celsius]] (°C)
* [[Fahrenheit]] (°F)
* [[Rankine scale|Rankine]] (°R or °Ra), which uses the Fahrenheit scale, adjusted so that 0 degrees Rankine is equal to [[absolute zero]].

Unlike the degree Fahrenheit and degree Celsius, the kelvin is no longer referred to or written as a degree (but was before 1967<ref name="Westphal_1952"/><ref name="CGPM_13_res_3_1967"/><ref name="CGPM_Res313_1967"/>). The kelvin is the primary unit of temperature measurement in the physical sciences, but is often used in conjunction with the degree Celsius, which has the same magnitude.

Other scales of temperature:
* [[Delisle scale|Delisle]] (°D)
* [[Newton scale|Newton]] (°N)
* [[Réaumur scale|Réaumur]] (°Ré)
* [[Rømer scale|Rømer]] (°Rø)
* [[Wedgwood scale|Wedgwood]] (°W)

==Kelvin==
{{main|kelvin}} 
The "degree Kelvin" ({{not a typo|°K}}) is a former name and symbol for the [[SI]] unit of temperature on the [[thermodynamic temperature|thermodynamic (absolute) temperature scale]].<ref name="Westphal_1952"/>  Since 1967, it has been known simply as the [[kelvin]], with symbol K (without a degree symbol).<ref name="CGPM_13_res_3_1967"/><ref name="CGPM_Res313_1967"/><ref name="SI-Borchure"/> Degree absolute (°A) is obsolete terminology, often referring specifically to the kelvin but sometimes the degree Rankine as well.

==Comparisons== 
* Boiling point of water: 100.0&nbsp;°C / 212.0&nbsp;°F
* Melting point of ice: 0.0&nbsp;°C / 32.0&nbsp;°F
* Typical human body temperature: 37.0&nbsp;°C / 98.6&nbsp;°F
* Room temperature: 20–25&nbsp;°C / 68–77&nbsp;°F<ref name="Lamar"/>

==Temperature conversions==
{{Timeline Temperature Conversion}}
All three of the major temperature scales are related through a [[linear equation]], and so the conversion between any of them is relatively straightforward. For instance, any Celsius temperature ''c''&nbsp;°C can be calculated from a corresponding Fahrenheit temperature ''f''&nbsp;°F or absolute temperature ''k''&nbsp;K.

:<math>\begin{align}
c \;=\; \frac{5}{9}(f - 32) \;=\; k-273.15
\end{align}</math>

The equations above may also be rearranged to solve for <math>f</math> or <math>k</math>, to give

:<math>\begin{align}
f \;&=\; \frac{9}{5}c + 32 \;=\; \frac{9}{5} (k-273.15) + 32\\
k \;&=\; c+273.15 \;=\; \frac{5}{9}(f - 32) + 273.15
\end{align}</math>

== See also ==
* [[Comparison of temperature scales]]
* [[International System of Units]]

==References==
{{reflist|refs=
<ref name="Westphal_1952">{{cite book |title=Physikalisches Wörterbuch |language=de |trans-title= |chapter=Nox, Dunkelleuchtdichte, Skot |author-first=Wilhelm Heinrich |author-last=Westphal |author-link=Wilhelm Heinrich Westphal |date=1952 |edition=1 |publisher=[[Springer-Verlag OHG]] |publication-place=Berlin / Göttingen / Heidelberg, Germany |isbn=978-3-662-12707-0 |doi=10.1007/978-3-662-12706-3 |pages=125, 271, 389 |url=https://books.google.com/books?id=QaCFBwAAQBAJ&pg=RA1-PA125 |access-date=2023-03-16 |quote-pages=271, 389 |quote=Dunkelleuchtdichte. […] Unter Zugrundelegung dieser Empfindlichkeitskurve hat man 1940 in Deutschland die Dunkelleuchtdichte mit der Einheit [[Skot (unit)|Skot]] (sk) so festgesetzt, daß bei einem Licht der Farbtemperatur 2360&nbsp;{{not a typo|°[[Kelvin (unit)|K]]}} 1&nbsp;sk&nbsp;= 10<sup>−3</sup>&nbsp;asb gilt. 1948 ist von der [[Internationale Beleuchtungskommission|Internationalen Beleuchtungskommission]] (IBK) die Bezugstemperatur auf 2046&nbsp;{{not a typo|°K}}, die Erstarrungstemperatur des [[Platinum|Platin]]s, festgesetzt worden. Die Bezeichnung Skot wurde von der IBK nicht übernommen, dafür soll "skotopisches Stilb" gesagt werden. Als höchstzulässiger Grenzwert für die Dunkelleuchtdichte ist in Deutschland 10&nbsp;Skot festgesetzt worden, um eine Verwendung der Dunkelleuchtdichte im Gebiet des gemischten [[Photopic vision|Zapfen]]- und [[Scotopic vision|Stäbchensehen]]s zu vermeiden, da in diesem Bereich die photometrischen Maßgrößen wegen der allmählich gleitenden Augenempfindlichkeitskurve ihren Sinn verlieren. […] Skot, abgek[ürzt] sk, Einheit für die Dunkelleuchtdichte, welche für zahlenmäßige Angaben und zum Anschluß der Dunkelleuchtdichte an die normale Leuchtdichte 1940 von der {{ill|German Lighting Society|de|Deutsche Lichttechnische Gesellschaft|lt=Deutschen Lichttechnischen Gesellschaft}} geschaffen wurde. Für diesen Anschluß wurde die Strahlung des [[Black body|schwarzen Körper]]s bei ''T''&nbsp;= 2360&nbsp;{{not a typo|°K}}, d.h. eine Strahlung der Farbtemperatur ''T''<sub>1</sub>&nbsp;= 2360&nbsp;{{not a typo|°K}} vereinbart. Eine Lichtquelle strahlt mit der Dunkelleuchtdichte 1&nbsp;sk, wenn sie photometrisch gleich einer Strahlung der Farbtemperatur ''T''<sub>2</sub>&nbsp;= 2360&nbsp;{{not a typo|°K}} und der Leuchtdichte von 10<sup>−3</sup>&nbsp;asb (Apostilb) ist. Bei der Farbtemperatur ''T''<sub>1</sub>&nbsp;= 2360&nbsp;{{not a typo|°K}} gilt also die Relation: 1&nbsp;sk&nbsp;= 10<sup>−3</sup>&nbsp;asb&nbsp;= 10<sup>−7</sup>/π sb. |trans-quote=}}</ref>
<ref name="SI-Borchure">{{cite web |title=Unit of thermodynamic temperature (kelvin) (International System of Units brochure, Section 2.1.1.5) |publisher=[[International Bureau of Weights and Measures]] |date= |edition= |url=http://www.bipm.org/en/publications/si-brochure/kelvin.html |url-status=dead |archive-url=https://web.archive.org/web/20141007053944/http://www.bipm.org/en/publications/si-brochure/kelvin.html |archive-date=2014-10-07}}</ref>
<ref name="Lamar">{{cite web |title=Metric system temperature (kelvin and degree Celsius) |publisher=Colorado State University - Lamar |date= |url=http://lamar.colostate.edu/~hillger/temps.htm |access-date=2009-02-10 |url-status=dead |archive-url=https://web.archive.org/web/20000116044337/http://lamar.colostate.edu/~hillger/temps.htm |archive-date=2000-01-16}}</ref>
<ref name="CGPM_13_res_3_1967">{{cite web |title=Resolution 3 of the 13th CGPM (1967) |website=bipm.org |publisher=BIPM |date=1967 |url=https://www.bipm.org/en/committees/cg/cgpm/13-1967/resolution-3 |access-date=2022-02-21}}</ref>
<ref name="CGPM_Res313_1967">{{cite web |title=Resolution 3: SI unit of thermodynamic temperature (kelvin) |work=Resolutions of the 13th CGPM |publisher=Bureau International des Poids et Mesures |date=1967 |url=http://www.bipm.fr/en/CGPM/db/13/3/ |access-date=2008-02-06 |url-status=dead |archive-url=https://web.archive.org/web/20070421013852/http://www.bipm.fr/en/CGPM/db/13/3/ |archive-date=2007-04-21}}</ref>

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[[Category:Units of temperature]]