Talk:Celsius/Archive 1

Concrete examples
Real-world examples

-20 Typical freezer 0 Freezing point of water 4 Typical refrigerator 22 Room temperature 30 Temperate climate 37 Body temperature 100 Boiling point of water

Definition
1 °C = 1 K, and absolute zero is -273.15 °C

Says the article. Complete nonsense. 1 °C = 274.15 K not 1K. This needs to be fixed.

Jimp 17Oct05

Now it's fixed. Jimp 19Oct05


 * Was it?! I still see it that way because Gene Nygaard decided to revert it back to that uncomprehensive form. For me it also is a nonsense and I was thinking about re-wording it. Now I do not want to be engaged in a editor war. -- 212.138.64.176 16:20, 20 October 2005 (UTC)

I think you're either missing the point or deliberately misunderstanding things Jimp.

It is stating that 1 degree on the Kelvin scale is equivalent to 1 degree on the Celsius scale. Which is correct. DurhamMatt

The correct statement is "A change of 1 °C = 1 K"

Wrong article and map
As a matter of empirical FACT, Fahrenheit is used quite widely in the UK. The Fahrenheit article likewise is WRONG. But hey, who cares about facts when Wikipedia editors decide to push an agenda? — Preceding unsigned comment added by 92.12.18.129 (talk) 08:25, 3 February 2022 (UTC)


 * Factual corrections are repeatedly undone by smug ignorant 'editors', with threats about 'vandalism'. No wonder Wikipedia is rightly regarded as a pathetic joke by true researchers. — Preceding unsigned comment added by 92.12.18.129 (talk) 07:55, 4 February 2022 (UTC)


 * Please read and understand Wikipedia's verifiability policy, especially the "burden of proof" section. To the extent that Wikipedia is sometimes considered unreliable, it is precisely because some editors who "know better" do not bother to back up their dubious assertions with citations to reliable sources. If you can document that the Fahrenheit scale is still considered "widely" used in the UK today, whether for weather forecasts, cooking recipes, or whatever, by all means feel free to do so; that way, the article will be both factually correct and easier to maintain if, in a decade or so, someone wants to check that the Fahrenheit scale is still used for the same purposes as in 2022. Thanks, Hqb (talk) 12:39, 4 February 2022 (UTC)

Precedence in article of "symbol typesetting"
Why is something of tertiary importance to the subject in the 2nd of 7 major sections? Typesetting should be (IMO) just before the references - if included at all. Alanbrowne (talk) 16:23, 11 May 2013 (UTC)

Centigrade & Capitilisation
My research indicates that the original name centigrade came about because there were 100 graduations (steps) between the freezing and boiling points of water, and that the name was changed to Celsius less from a desire to recognise the man himself but more a desire to end confusion caused by:
 * the metric system use of centi as a prefix for 1/100th (which would seem to indicate, incorrectly, that a centigrade is 1/100th of a "grade"). (Centigrade pre-dates metric by over 50 years.)
 * a whole bunch of European languages having their word for degree be similar to "grade"

Don't have conclusive evidence yet though.

Also, NIST and other standards bodies around the world seem to agree that Celsius should always be capitalized when spelt out.


 * The capitalization is a quirk of the English language, where the names of units are not capitalized, but proper adjective identifying particular units are. It's a noun versus adjective thing, not some strange rule only applicable to this unit.  Thus degrees Celsius, degrees Rankine, degrees Fahrenheit, but volts, watts, newtons, and becquerels.  Note that the K was capitalized before 1967 when the units were called "degrees Kelvin" but "kelvins" are not capitalized.  Gene Nygaard 05:57, 16 Feb 2005 (UTC)

I do not follow why 'centigrade' is confusing. A degree Celsius is 1/100 of a 'grade' between 0 and 100 degrees. Could someone explain this more clearly?


 * If you say "The temperature is 25 centigrade." and your language's word for "degree" sounds a whole lot like "grade", then somebody (that knows the metric system better than the Celsius temperature scale) might interpret this as «The temperature is 25 hundredths of a degree.», which is not what you meant! -- Toby Bartels 11:59 1 Jun 2003 (UTC)

There is a general trend in science to use a captial letter for a proper name, but it is not strict. For example, 5.2Mt is 5.2 mega tonnes. This differentiates milli from mega. Micro uses the Greek letter mu. C is not used elsewhere as a multiplier, so I suspect it always stood for the proper name Celsius. Such details may not lend themselves to historical investigation, unless there was a widespread acceptance of what C stood for.220.244.75.119 (talk) 09:08, 28 May 2014 (UTC)

Toby Bartels' explanation is a lot clearer than what is in the article. Ccrrccrr (talk) 00:49, 6 November 2016 (UTC)

Ego
Also, I believe that renaming physical quantities to honor a person, such as 'cycles per second' to 'Hertz', is to me an imposition of human ego on the perfection of the Universe. David 21:10 Apr 27, 2003 (UTC)


 * I disagree, but it any case it was renamed Celsius and that is its name, and what it is called worldwide. ÉÍREman 23:48 Apr 27, 2003 (UTC)
 * I prefer to say 100 megahertz to 100 megacycle by second. Not you? -- Looxix 00:22 Apr 28, 2003 (UTC)

No one has ever said '100 megacycle by second'. The correct usage was '100 megacycles'. (The 'per second' was implied.)


 * Not by the Furlong/Firkin/Fortnight system of measurement. 100 megacycles without a time qualifier would be "100,000,000 cycles per fortnight". 100MHz is explicit to "100,000,000 cycles per second", no matter the system of units you're in. If you're wondering, the FFF system is still in use on VAX systems, as part of the operating system.--220.253.40.67 10:30, 22 January 2007 (UTC)

We only prefer "Megahertz" now to "megacycles" because we have become used to it. That is how language naturally changes, through common usage. That does not make one term better than another. "Megacycles" is better than "Megahertz", in my opinion, because it is more descriptive of the physics involved. David 16:30 Apr 29, 2003 (UTC) ''
 * But "cycles" works only in English and is therefore utterly useless as an international standard! Names are fairly language neutral. Markus Kuhn 17:10, 10 December 2005 (UTC)


 * Additionally, "cycles" doesn't work. Sure, for AC electrical currents or sound waves. But Radioactivity is measured in "particles released per second", which is expressed as s-1 as well. Hertz isn't "cycles", it's "events". This gets even more unweildy: "100 MEGA-EVENTS! WHOA! THAT'S EXTREEEEME, DUDE! Wait, you weren't talking about skateboarding?"--220.253.40.67 10:36, 22 January 2007 (UTC)


 * "'Megacycles" is better than "Megahertz" because one better represents the perfection of the universe? Talk about an ego...12.192.132.130 (talk) 18:22, 10 June 2008 (UTC)
 * The Universe hath no ego, else if it doth then 'tis the collective whole of all of its constituent parts :P Firejuggler86 (talk) 02:05, 7 February 2021 (UTC)

Fahrenheit
Yes, the USA, and Jamaica, apparently, are the last holdout for Fahrenheit for everyday, non-scientific temperature measurement, but Wikipedia editors should not parlay their annoyance at this situation into non-NPOV prose. As of today, I've toned down the text in this article and in the Fahrenheit article so that it reads less like commentary. There is no need to mention that Europeans find it "puzzling" that the USA is one of a "declining number of countries" "still" using this system, phrases which together imply fault. - mjb 00:47, 10 Apr 2004 (UTC)

In the United States will stay temperature "Fahrenheit". - Ronald20 18''':15, 06 June 2006 (UTC))

Wikipedia could really use a way to let the reader see their own preferred units. Since .org is a USA domain... yup, we like our Fahrenheit. The same goes for any other unit. So how about some Wiki syntax that lets the editor use units they prefer, while not annoying the reader? Otherwise I propose to fix all this senseless Celsius stuff. :-)
 * Nope, .org.us would be a USA domain...
 * Not really because we invented the system, they are all US domains unless otherwise specified, with a ".UK" or whatever one of the lesser countries choose to use.

Well, if it were any other country in the world, the USA would be among the most prominent to pressure the country to finally adopt to the system every other country is using. J I P | Talk 07:18, 18 May 2007 (UTC)

Original freezing and boiling points
According to some sources (such as http://susning.nu/Celsius for the fortunate few who read Swedish) Anders Celsius first defined 100 degrees as the temperature at which water freezes and zero degrees as the temperature at which water boils (the advantage of this, I suppose, being that outdoor temperatures would always be in the positive range). Before the scale became used to any measurable extent, however, this was changed to what we're used to today.

If this is true, it should perhaps be noted in the article.


 * See the third paragraph. Note that the Delisle scale also runs "downward".


 * Urhixidur 13:46, 2004 Nov 18 (UTC)

From my science education the original scale had four elements which should all be mentioned: (1) Freezing temperature of water, defined as 0; (2) Boiling temperature of water, defined as 100; (3) Measurement of (1) and (2) at standard atmospheric pressure, sea level, (4) Linear interpolation between 0 and 100 and extrapolation below 0 and above 100. I think it's important to explicitly state the linear nature of the scale, otherwise it is an unstated assumption.


 * Jberkes 2004-12-24

The table is on - http://en.wikipedia.org/wiki/Celsius 2011- 09- 29 — Preceding unsigned comment added by 74.220.169.123 (talk) 13:59, 29 September 2011 (UTC)
 * if the first statement were to be true, the "mathematic equation" to convert Fahrenheit to celsius would not work**

Preferred scale. bah.
The sentence

"Fahrenheit remains the preferred scale for everyday temperature measurement, although Celsius or kelvin are used for scientific applications."

should either be changed to reflect that it s NOT the preferred scale in Europe or like, or it should be removed.

Actually I don't know of the Fahrenheit use, other than in US.


 * Read it again. This is the sentence you partially quoted:


 * In the United States and Jamaica, Fahrenheit remains the preferred scale for everyday temperature measurement, although Celsius or kelvin are used for scientific applications.


 * --Yath 23:22, 28 Dec 2004 (UTC)

Don't bother telling that euro anything all the good ones were killed in ww1 and ww2. —Preceding unsigned comment added by 75.187.183.85 (talk) 22:37, 10 January 2008 (UTC)

Conversion Method
Why does the article say: "a method for converting Celsius to Fahrenheit is to add 40, multiply by 1.8, and subtract 40." etc. (huh??)

...but the sidebar says: °F = °C × 1.8 + 32

johnq 09:20, Dec 29, 2004 (UTC)


 * Someone having fun with math. It seems irrelevant to me. Both methods are correct, though. --Yath 07:14, 2 Jan 2005 (UTC)


 * Just rolled back a delete of that section. It is mathematically identical. The method quoted writes out as:
 * °F = (°C + 40)×1.8 - 40
 * = °C×1.8 + 40×1.8 - 40 = °C×1.8 + 40×(1.8 - 1) = °C×1.8 + 40×0.8 = °C×1.8 + 32
 * QED
 * Urhixidur 15:28, 2005 Feb 19 (UTC)


 * It is an easier pair of formulas to remember&mdash;or at least, easier to reconstruct, once you understand the principle behind it. Gene Nygaard 16:36, 19 Feb 2005 (UTC)


 * Can anyone tell me why it must be 40? Yves Revi 21:05, 27 October 2006 (UTC)


 * Because -40 °C = -40 °F. Birdhurst 23:59, 20 January 2007 (UTC)


 * No, it's because 32/0.8=40


 * In fact user Birdhurst is correct. The formula with 40 is nicely 'centred' according to statistical principles, but doesn't appear to be easier to remember or use, except in special cases such as converting 60 °C (where you then get to multiply 1.8 by 100 instead of 60). — DIV (128.250.204.118 08:46, 1 September 2007 (UTC))

Capitalisation
The article currently seems to spell celsius with a captial letter when refering to the measurement of temperature. I always thought the general rule was that when units are named after a person then when the full name is spelt out there is no capitalisation, however when just the initial of the unit is used then it is in capitals. So for example you would write 10 degrees celsius or 10 °C. The units watt, joule, volt, newton, farad, henry and tesla all seem to follow this rule. Is there an exception for celsius? or is the article wrong? -- Popsracer 02:15, 25 Jan 2005 (UTC)


 * To answer my own question, this has been discussed in Talk:Kelvin and degrees Celsius seems to be the correct form -- Popsracer 02:22, 25 Jan 2005 (UTC)


 * The text reads in part: « The degree Celsius is the only SI unit whose full unit name [...] in English includes an upper case letter. That is a quirk of English, because it is a proper adjective rather than a noun (before the name was changed from "degrees Kelvin" to "kelvins" in 1967, that was another SI unit containing a capital letter in English) ».
 * This seems a little too strong on the "quirk of English" part, leaving the reader with the impression that this happenstance is peculiar to English. It is not, the situation being precisely the same in French, the SI's official language. I don't know about other languages, but I suspect the case will be oft repeated. German may be an exception, since it capitalises all nouns. Anyway, I think we need to soften the statement a bit. But how?
 * Urhixidur 22:22, 2005 July 28 (UTC)


 * I deleted the part about "quirk of English" because it made no sense to me. Units like ampere, hertz, newton, etc. are not considered proper nouns even though they are derived from a person's name. So there's no logical reason for "Celsius" to be considered a proper adjective, other than "that's just how it is". --Mathew5000 06:32, 21 June 2006 (UTC)

Re-definition
When was celsius redefined in terms of kelvin? The article doesn't say. —Ævar Arnfjörð Bjarmason 07:39, 2005 Mar 15 (UTC)


 * Maybe because it is never explicitly stated that way in a CGPM resolution, which would make it easier for those writing these articles. The 9th CGPM in 1948 endorsed the recommendation of the CCTC (a consultative committee organized under the CIPM to advise the CGPM)
 * In consequence the Comité Consultatif de Thermométrie et Calorimétrie (CCTC) considers that the zero of the centesimal thermodynamic scale must be defined as the temperature 0.0100 degree below that of the triple point of water.
 * (Note that though this uses "centesimal" a later resolution of the 1948 CGPM chose "degrees Celsius" from among the three names then in use, and said centesimal and centigrade should no longer be used.) Yet the CGPM also said
 * The CCTC accepts the principle of an absolute thermodynamic scale with a single fundamental fixed point, at present provided by the triple point of pure water, the absolute temperature of which will be fixed at a later date. The introduction of this new scale does not affect in any way the use of the International Scale, which remains the recommended practical scale.


 * This information is from the PDF version of the SI brochure available at http://www.bipm.org and it might also be included in the html materials available there, though I haven't checked that.


 * However, it wasn't until their next meeting, the 10th CGPM (1954) that the triple point of water was set a 273.16 kelvins (then still called degrees Kelvin) Until this was done, setting the zero point of the Celsius scale at 0.0100 degrees below the triple point of water wasn't sufficient to define a scale with a single fixed point, because the size of the degrees was yet to be determined.


 * The definition was further clarified&mdash;in addition to changing the name to kelvins&mdash;by the 13th CGPM in 1967-1968). I wouldn't consider this to be any change at all, merely a clarification of what already existed because some people were misinterpreting it.   So I'd day the change was complete by 1954.  Gene Nygaard 14:26, 15 Mar 2005 (UTC)
 * Thanks, I think this should be added to the article. —Ævar Arnfjörð Bjarmason 21:30, 2005 Mar 15 (UTC)

"Celsiheit" and the British media

 * This combination of the two scales has been called the 'Celsiheit' scale. Presumably the 'Celsiheit' scale is Celsius below room temperature (about 20 °C) and Fahrenheit above.

I removed this section from the article because it does not seem to be in common usage - a Google search revealed only one reputable use, on the UK Metric Association's website.


 * It has become common in the British media to drop the term 'degree' in speech and text and refer to a temperature as 21 Celsius, for example, as though Celsius were units and not a scale.

I also removed the above. Whilst this is an interesting indicator of the increasing innumeracy of the British public, it doesn't seem specifically relevant on a page about the Celsius scale.

--Hex 13:36, 30 May 2005 (UTC)

Centigrade same as Celsius?
I seem to remember when the BBC changed from using centigrade to celsius in weather forecasts that the explanation was that they were not the same. Centigrade was defined by graduating the points for 0 and 100 on a particular measuring device into 100 equal parts, whereas celsius was done by graduating between 0 and 100 with 100 equal temperature changes. These two would be different if the expansion of the say liquid in the device was not uniform over the range 0 to 100. Is my memory faulty or the explanation or both? Bornintheguz 1 July 2005 18:44 (UTC)


 * If Centigrade were defined according to the graduations of an arbitrary measuring device, it would not really be a unit of temperature. Temperature itself is well defined by physicists as a measure of the mean kinetic energies of particles in a material at thermal equilibrium. However, I agree that there seem to be differences of opinion regarding the equality of "Centigrade" and "Celsius". I was taught that Centigrade was (and still is) defined by the original two fixed points, namely the freezing and boiling of water at standard pressure; meanwhile Celsius was redefined as described in the article, using absolute zero and the triple point of water as its fixed points (thus removing any dependence on the kilogram, metre and second, which are needed to define "standard pressure").

Before the 9th CGPM, 1948, Celsius and Centigrade were both used to denote the same unit of temperature defined by the freezing and boiling points of water. In 1948 the unit was re-defined based on the triple point of water and at the same time its name was standardised to Celsius. It then appears that Centigrade was never the correct term for the new definition. I then guess that technically, if mentioning degrees Centigrade, one should be referring to the temperature as measured before 1948, which would then imply the old scale. --Brunik (talk) 12:09, 3 March 2009 (UTC)

- Actually that's not entirely true.. The Kelvin is the SI unit of tempertaure based on the ideal gas equation, a linear scale relating to the tripple point of water (273.15 by definition) and can only occur at one value of P and T and such is reproducible internationally. The ice point is the temperature at which ice and air-saturated water co-exist at equilibrium at a pressure of 1 atm. The centigrade scale gave 0 degrees at the ice point of water and 100 degrees at the steam point and was a function with 100 grades between the two points. The steam and ice points were hard to reproduce sufficiently accurately so the celcius scale was devised which was based on the same grading as the original centigrade scale but used the tripple point of water as the fixed point and had the same grading as the centigrade scale, this gives an ice point of 0C and a steam point of 99.97C. - Thermodynamics can be pedantic!

I've changed the opening line to include historically, since centigrade and Celsius are not the same, with a reference to it. Please do not revert!! Discuss here. I understand the Encyclopedia Britannica says one thing, but to be honest it's clear they just wrote that out without due process of the differentiation. Of course, edit to clarify but the intent is to maintain that "centigrade" is not and should not be used as a measurement unit.Cpt ricard (talk) 00:40, 17 March 2015 (UTC)

Move to "degree Celsius"?
Since the name of the unit is "degree Celsius", shouldn't the article be moved there? I hesitate because it implies a lot of redirect checking...

Urhixidur 12:48, 2005 July 28 (UTC)


 * It would also involve the other temperature scales as well (Fahrenheit, Rankine, Réaumur; the others that never were used much anywhere probably all have "scale" in their names).
 * I've always thought that this would be good, encouraging people not to use Celsius standing alone and to link the whole name of the unit. A redirect would still take care of entering just Celsius into the Go/Search box.
 * Of course, for those linking purposes, "degree Celsius" is much more useful than "Celsius scale" as in those other scales (which aren't linked to except from the other temperature units anyway, so there would be little reason to bother changing them, and not much to it if we chose to do so). Gene Nygaard 13:29, 28 July 2005 (UTC)

Celsius as SI
I changed it from reading "an SI unit" to simply "a unit" given that it isn't technically an SI unit. If I am off-base, that is fine, but as I understand it, kelvins are the only SI units of temperature. Tmrobertson 05:14, 5 November 2005 (UTC)

And I changed it again to an "SI derived unit" based on what has been already established in the SI page. Sorry if I covered old ground. Tmrobertson 05:18, 5 November 2005 (UTC)


 * You had it correct the first time. Celsius is NOT an SI unit, nor is it a "derived SI unit".  The article is wrong as written.  SimpsonDG (talk) 00:31, 7 January 2018 (UTC)

Content dispute
On 2005-09-11 12:39:50 Bobblewik "copyedited" the article from this to this diff, since then the article has in my opionion gotten drastically worse. For instance it now claims in the first paragraph that the unit is defined with the freezing point of water at 0 degrees and the boiling point at 100 degrees, but in reality the unit hasn't had a definition that's anything like that since 1954!, and even before then it was 0 and 100 at standard atmospheric pressure. That's not the only problem with that version however, it split content into multiple sections that could easily have fitted as prose in the first paragraph etc. —Ævar Arnfjörð Bjarmason 20:43, 21 November 2005 (UTC)


 * The introductory section shoud be addressed primarily to non-experts. As such, it really must focus on the freezing and boiling point of water as the most well-known informal reference points for the Celsius scale. The exact modern CGPM definition, whether it is through the triple-point of water, or through the many additional triple points listed in the ITS-90, is specialist knowledge that can be explained in a later section in detail (or better moved into the ITS-90 article). Remember that this is an encyclopedia for the general population, and not a thermodynamics or metrology textbook! Our readers range from 8-year old kids to physics PhDs, and we need to address all of them. Your last edits overemphasised in the introduction a minor metrological technicality at the expense of general accessability. This needs to be fixed. Markus Kuhn 11:19, 10 December 2005 (UTC)
 * The intro should be convey the facts of the matter, which is that the scale is currently defined like that and hasn't been defined in the way most think it's defined like in over 50 years. You could add a mention that some mistakenly think that it's still defined like that however. —Ævar Arnfjörð Bjarmason 15:08, 10 December 2005 (UTC)
 * The facts! The facts!  Wikipedia must represent the facts!  Why always not the facts!?  —Preceding unsigned comment added by 12.192.132.130 (talk) 18:30, 10 June 2008 (UTC)

IF and ONLY IF Wikipedia is "aiming" at scientists and engineers, then yes - I would agree with you. The fact is that Wikipedia is not meant strictly for engineers and scientists, and in general - when people come to Wikipedia, they are looking for common answers to common questions. Therefore, the definitions of 0 deg C (freezing) and 100 deg C (boiling) are PERFECTLY ADEQUATE and appropriate. This scientific "look how smart I am" nit picking over and re-writing of articles has GOT to stop. Very few people in the real world care about .01 deg Celsius, or the 1948 ... blah blah history of how the units are defined, limits, boundaries, etc. IF they do, then let them drill down to the appropriate section wherein you all can flex your superior intellectual powers and show that, indeed, you know all about the Celsius temperature scale. I get tired of having to come here and write these rants discouraging bad behavior. In its most vulgar form, it is nothing more than a bad case of Intellectual Elitism. Wikipedia has slowly been taken over by people who seem to be stricken with Asperger's Syndrome. For those of you who need to continually display your intellect, might I suggest a return to academia, where you can publish inane articles to your heart's content; and to the amazement of your friends and colleagues. Here in Wikipedia land, it just puts people off and discourages them from reading. Which is a BAD THING. tjp in Houston — Preceding unsigned comment added by 98.194.39.86 (talk) 22:42, 19 June 2016 (UTC)

History

 * "Several other people, including Elvius from Sweden (1710) and Christian of Lyons (1743)..."

Who is "Christian of Lyons" - it sound like a medieval person. : ) "Elvius from Sweden" is almost certainly Pehr Elvius the Elder, who was one of the predecessors of Celsius in the Uppsala chair of Physics, as well as his uncle by marriage. But in the bios I find on Elvius, I see nothing connected to this issue. The history section needs checking and referencing. up◦land 09:40, 10 December 2005 (UTC)
 * Possibly "Christian of Lyons" refers to Jean Pierre Cristin (1683-1755) who in 1743 proposed an inverted version of the scale with the freezing point at 0 °C (32 °F) and the boiling point at 100 °C (212 °F) which he named Centigrade. --Friedfish 11:33, 27 July 2006 (UTC)


 * I believe you're referring to Elvis, who did indeed refer quite frequently to temperature. "Hunk a Hunk of Burning Love" would be one example.  To my knowledge, however, I don't believe Elvis ever actually called out a specific temperature or scale.  It was mostly about burning or freezing.  I'm afraid he left us with that conundrum, and we will have to interpret it as context allows.  As such, I don't think it would appropriate to refer to Elvis in an article dedicated to the Celsius scale.  tjp in Houston  — Preceding unsigned comment added by 98.194.39.86 (talk) 22:47, 19 June 2016 (UTC)

Page name for temperature articles
Please see the discussion at Talk:Units of measurement because it affects several units of measurement. bobblewik 22:03, 12 February 2006 (UTC)

Celsius in the United States
In the United States will switch from Fahrenheit to Celsius. Ronald20 20:00, 10 June 2006 (UTC)

However, in the United States not yet switched to temperature Celsius. They still used a temperature Fahrenheit. Ronald20 18:21, 15 June 2006 (UTC)


 * Can I politely recommend that you check your English with a friend — I can't understand the point that you're making here. — DIV (128.250.204.118 08:52, 1 September 2007 (UTC))


 * I think he meant that he heard/read that the US was switching from Fahrenheit to Celsius, but they have yet to do so, so he is wondering why. I would ask where you got this information.  —Preceding unsigned comment added by Darktangent (talk • contribs) 01:25, 24 April 2010 (UTC)


 * As with many other standards, the USA is partly switched already. The FAA reports Celsius temperatures in coded aviation weather reports.  On the other hand, while they say "Temperature/Dewpoint: Each is reported in whole degrees Celsius using two digits;", at the same time they'll decode in a local report that today's temperature is "46°F".  As a result, the FAA is continuously saying that they intend to fix this problem. Santamoly (talk) 15:40, 3 May 2010 (UTC)

Freezing and boiling points of water
A pedantic objection, perhaps:

According to the table, the freezing point of water is "0" and the boiling point is "100" on the Celsius scale. This would suggest one of two things: either (a) these temperatures are EXACT, by definition, or (b) they are only known to the nearest one degree. Neither is true. I don't know whether anyone has measured the freezing and boiling points of water (at standard pressure) with enough precision to distinguish the "new" scale from the "old" one; I searched on Google for a while and couldn't find anything. But naively I would expect any deviation to occur around the 3rd decimal place, since absolute zero and the triple point are defined at two decimal places (i.e. the freezing point of water at standard pressure is likely to be 0.00x or -0.00x, where x is some non-zero digit).

To avoid this ambiguity, I would suggest changing the freezing and boiling points to 0.00 and 100.00, unless someone can find an accurate authoritative measurement. Mtford 04:07, 19 June 2006 (UTC)


 * Any trailing zeros behind the decimal point are meaningless, and should be ignored. Mathematically, 0 is the exact same number as 0.00, with 0 being more common and accurate - and readable.  Writing trailing zeros is only common in certain applications, such as computer programming where numerical formats are important.  In this case, numerical formats are not important, and the average reader would just be confused by such.  By your line of thinking, 0.0000 would be even better, and we could then improve on that "accuracy" by adding even more trailing zeros.  How many would you like?   Why not just insert some common term like "approximately" or "almost exactly"?  Or better yet, leave it alone.  Most people understand that there are no (very few) absolutes.  tjp in Houston  — Preceding unsigned comment added by 98.194.39.86 (talk) 22:53, 19 June 2016 (UTC)

When and by whom was the scale reversed?
I've been trying to find a reference for the fact that the scale was reversed, and I've been running into some inconsistencies. I haven't found anything really authoritative (in many cases it's just a footnote), and different books give different dates and authors of the reversal. I found these searching for "celsius 1744 reversed" and "celsius reversed" in Google Books. Here are some results:


 * A Philatelic Ramble Through Chemistry - Edgar Heilbronner, Foil A. Miller: Reversed in 1750 by Stromer or Linné.
 * Foundations of Engineering - Mark T. Holtzapple, W. Dan Reece: Reversed by Celsius himself in 1743.
 * Advanced Engineering Thermodynamics - Adrian Bejan: Reversed in 1747.
 * Applied Dimensional Analysis and Modeling - Thomas Szirtes: Reversed in 1743
 * Mathematically Modeling the Electrical Activity of the Heart: From Cell to Body Surface and Back... - edited by Andrew J Pullan, Martin L Buist, Leo K Cheng: Reversed after his death in 1744
 * How Do We Know the Laws of Thermodynamics - Jeffrey Moran: Reversed by Celsius himself in 1743.
 * Temperature Measurement - L. Michalski, K. Eckersdorf, J. Kucharski, J. McGhee: Reversed by Stromer after Celsius's death.
 * The Merriam-Webster New Book of Word Histories - Merriam-Webster: Reversed in 1747.
 * Chemistry & Chemical Reactivity - John C Kotz, Paul M Treichel, Gabriela C Weaver: Reversed after his death.
 * Mixture and Chemical Combination: And Related Essays - Pierre M Duhem: Reversed by Linné.
 * Medical Technology: Inventing the Instruments - Robert Mulcahy: Reversed by Celsius himself in 1743.

I found some old books about Celsius in my university library, but all of them seem to be in Swedish, which I don't read. Itub 18:51, 19 July 2006 (UTC)

I searched "Jean Pierre Christin" and found this book "A Chronology of Microbiology in Historical Context" which claims Christin inverted it in 1743. Ctchou 13:23, 16 April 2007 (UTC)

SI unit
I just checked the SI page, and it doesnt seem like degrees Celsius is a SI unit at all - kelvin is, Celsius is just a common unit. Am I wrong?Yarilo2 03:15, 22 September 2006 (UTC)

·Never mind. I see now that degree celsius is not a unit of SI but rather a derived unit of SI, which still counts. Cheers,Yarilo2 03:24, 22 September 2006 (UTC)

Incorrect history
Someone needs to carefully look at the history section and correct it if necessary. The information (misinformation?) there keeps getting repeated on the Internet by other sources that simply copy what Wikipedia says. I'm not going to do it because I don't have the stomach for the holy wars that result from wholesale deletions of information; even when it's completely incorrect. First, the un-cited claim that botanist Carolus Linnaeus was not responsible for reversing Celsius' scale to its current form is contrary to authoritative sources such as Thermodynamics-information.net: A Brief History of Temperature Measurement and, Uppsala University (Sweden): Linnaeus’ thermometer. That second reference is the botany school that Linnaeus founded. Furthermore, the notion that water's boiling point would be defined at a pressure of only 1000 mbar is highly suspect. Such a pressure (as opposed to the median seal-level value of 1013.25 mbar) would produce a boiling point on today's Celsius scale of 99.632 °C. This flies in the face of the practical reality of the time: Paris, where many of these standards were set, is only about 45 to 58 meters above sea level. All the modern SI work (acceleration of gravity, densities, temperatures) were originally predicated upon sea-level pressure at the latitude of Paris. Water's boiling point has always been defined at one standard atmosphere. As far as I know, this "1000 mbar" idea is the modern product of a 1985 IUPAC decision for measuring the physical properties of substances including the chemical elements. Greg L 02:58, 5 October 2006 (UTC)


 * OK, maybe I do have the stomach.  Greg L 19:13, 5 October 2006 (UTC)


 * Thanks very much for a well referenced correction. My memory was that there was a good case for it being "degrees Linnaeus" but Mr. C had the right initials to match Centigrade. The Uppsala article rightly gives a more even handed appraisal, as both contributed. Good stuff! ..dave souza, talk 21:48, 5 October 2006 (UTC)


 * You're most welcome Dave. Other than being able to admire one's own handiwork and pat one's self on the back, there's not much reward in writing Wikipedia articles. Small tokens of appreciation like yours go a long way and are like another gallon of gas in the tank: good for another 30 miles.  Greg L 23:14, 5 October 2006 (UTC)

World-wide adoption (Celsius and Kelvin)
As it was written: “Throughout the world (except for the U.S.), the Celsius scale is used for most temperature measuring purposes. The entire scientific world (the U.S. included) uses the Celsius and Kelvin scales. Many engineering fields in the U.S., especially high-tech ones, also use the Celsius scale. The bulk of the U.S. however, (its lay people, industry, meteorology, and government) relies upon the Fahrenheit scale. Jamaica is currently converting to Celsius. ” …it doesn't make sense to mention the Kelvin scale for science if all the other scales for the other uses aren't also disclosed. One begins running off on a tangent by introducing the subject of a thermodynamic scale (kelvin) which isn't the subject of this article. Completing these tangencies all the way for consistency results in a paragraph that reads as follows:


 * Throughout the world (except for the U.S.), the Celsius scale is used for most temperature measuring purposes. The entire scientific world (the U.S. included) uses the Celsius and Kelvin scales. Many engineering fields in the U.S., especially high-tech ones use use the Celsius, Kelvin, and also the Fahrenheit scales. The bulk of the U.S. however, (its lay people, industry, meteorology, and government) relies upon the Fahrenheit scale. Jamaica is currently converting to Celsius.

The whole point of this paragraph is to address who's using the Celsius scale. That's why the sentence regarding the scientific world would properly tell that it uses the Celsius scale—not that it measures temperature exclusively with the Celsius scale; just that it uses it. In the case of the lay person in the U.S., Fahrenheit must necessarily be discussed simply because of the conspicuous fact that the Celsius isn't used for this widespread audience. For logical consistency, the most straightforward wording for where the Celsius scale is used is as follows (emphasis added here only):


 * Throughout the world (except for the U.S.), the Celsius scale is used for most temperature measuring purposes. The entire scientific world (the U.S. included) uses the Celsius scale. Many engineering fields in the U.S., especially high-tech ones, also use the Celsius scale. The bulk of the U.S. however, (its lay people, industry, meteorology, and government) relies upon the Fahrenheit scale. Jamaica is currently converting to Celsius.

The above: “The entire scientific world (the U.S. included) uses the Celsius scale.” is an absolutely true statement and properly sticks to the simple subject of who is using the Celsius scale. As written, this paragaph doesn't try to pretend to enumerate every scale currently being used for these different disciplines. Greg L 04:35, 13 October 2006 (UTC) 
 * If you say "U.S. scientists use the Celsius scale" it risks the interpretation "U.S. scientists use only the Celsius scale (and no other)". — DIV (128.250.204.118 08:57, 1 September 2007 (UTC))

18 October Vandalism: Consequences
Vandalism doesn't always go unpunished. The IP address (208.220.136.66) from which some contributors vandalized this Celsius article traced back to The Potomac School in Virginia. It's a fine, K-12 private school three miles from Washington D.C. There was something about the nature of the vandalism (including this choice entry: “everybody is a gay fagg in the world”) that led me to feel grown-ups ought to know about it. So I informed the school’s officials. Through fortuitous timing, I happened to have contacted the school’s authorities roughly three hours after it happened. I received the following reply from a school administrator several hours later:

I appreciate everyone's work on this. I have spoken to the boy who admits to being the author of two of the quotes, and he has mentioned another boy who I will speak to tomorrow. He is probably reponsible for the third quote. The only question is regarding quote number 2, but I expect that they will provide that information tomorrow. Please rest assured that there will be serious consequences for all involved. I really appreciate your quick action in letting us know.

The part that's noteworthy about this is that this kid was confronted in a Virginia private school about four hours after he anonymously committed some vandalism to an article on the Web. If I was a ninth-grader and this happened to me, I'd sure be shocked. Signed: [Anonymous (to help avoid other acts of vandalism) on Wednesday, October 18, 2006 at 21:52]


 * The following day (19 Oct 06), in response to a follow-up e-mail I sent them explaining about the Wikipedia community, I received the following from a school administrator:


 * …thanks for the e-mail- we have three problems with [what the boys left on Wikipedia]: 1.the nature of them; 2, the vandalism; 3 the fact that they infringed our trust. Most likely the boys involved will face some sort of suspension as well as a requirement to make some sore of restitution to the community in the form of community service.  I cannot thank you enough for letting bus know- you have done the boys a real service.


 * …and I also received this from a faculty member:


 * I have to say that I really appreciated your email that you sent. It really struck a chord in me.  [A family member] is a frequent contributor to Wikipedia (mostly in the areas of theoretical and quantum physics) and I know what an important resource Wikipedia is.


 * My hope is that these students will learn from this experience and one day be positive contributors to Wikipedia.


 * [Anonymous (to help avoid other acts of vandalism) on Thursday, October 19, 2006 at 20:08] — Preceding unsigned comment added by 67.185.144.183 (talk • contribs)

Symbol for degrees Celsius
The statements that I just took out, but probably haven't completely fixed yet, about the usage for temperature intervals, indicate a gross misunderstanding of the actual resolution of the 13th CGPM, especially the point number 2:

1. the unit of thermodynamic temperature is denoted by the name “kelvin” and its symbol is “K”; 2. the same name and the same symbol are used to express a temperature interval; 3. a temperature interval may also be expressed in degrees Celsius; 4. the decisions mentioned in the opening paragraph concerning the name of the unit of thermodynamic temperature, its symbol and the designation of the unit to express an interval or a difference of temperatures are abrogated, but the usages which derive from these decisions remain permissible for the time being.

Even though it comes before point 3, rule 2 applies to it as well. The proper, current symbol is °C, in any context, whether a temperature reading or a temperature interval. The 1948 rules were "abrogated" in the legalese of this 1967-68 resolution. Gene Nygaard 02:47, 7 November 2006 (UTC)

In other words, a big part of the whole philosophy of this resolution was the clarification that the "thermodynamic temperature" and a "temperature interval" are not really different things. So let's not try to step back into the past in our article here. Gene Nygaard 02:49, 7 November 2006 (UTC)

See, for example, SAE Technical Standards Board Standard 003 (TSB-003), May 1999, ''Rules for SAE Use of SI (Metric) Units"

Note the use of °C for a temperature interval.

See also the use by NIST in its extensive tables of conversion factors in SP811. Gene Nygaard 03:12, 7 November 2006 (UTC)


 * These are just examples of people who've used sloppy notation. They are using the symbol °C because it fits better into a formula notation. The same goes for the °F example. The official policity of the BIPM (an international standards body, not a French one) still stands that an interval must use the word "degree" or "deg". You will not find on the BIPM web site, anything that says an interval may be expressed as °[symbol].   Greg L 18:50, 7 November 2006 (UTC)


 * No, it does not. You are just confused. Gene Nygaard 19:02, 7 November 2006 (UTC)


 * We'll see. I've been corresponding with Dr. Quinn on the history of the name of the scale. I've just e-mailed him regarding this too. Greg L 19:12, 7 November 2006 (UTC)


 * The 1967 resolution is clear as blazes as to what was abrograted and what was decided. Greg L 19:17, 7 November 2006 (UTC)

Resolution 3 and Resolution 7
Gene: There's no misreading. In Res 3 (1967), when they write "the same name and the same symbol are used to express a temperature interval;", they are referring to kelvin. When they write, "a temperature interval may also be expressed in degrees Celsius;" they are referring of course to Celsius and there is nothing in that abrogates what was written in Res 7 (1948) when they state "To indicate a temperature interval or difference, rather than a temperature, the word "degree" in full, or the abbreviation "deg" must be used." One still isn't supposed to write "an increase of 1°"; it's "an increase of one degree." Greg L 18:36, 7 November 2006 (UTC)

See this link for a classic example of how the BIPM uses increments: http://search.bipm.org/cs.html?url=http%3A//kcdb.bipm.org/appendixb/appbresults/CCPR-S2/CCPR-S2_Technical_Protocol.pdf&qt=degree+C&col=bipm&n=2

In it, they report a coefficient of ".0000189 per dgree C " “It is not .0000189 per °C” Greg L 18:47, 7 November 2006 (UTC)


 * See this : "stable to better than 0.005 °C during a series of measurements"


 * or this: "was measured in CMI 0.0003 mH/°C with an uncertainty (k=2) of 0.0001 mH/°C"


 * or this: "of 23.0 °C ± 0.1 °C."


 * or this: "temperature of the probe remains within +/- 0.2 °C of the entered value, the readout of the meter is taken as accurate."


 * I don't suppose you even know what the word "abrogated" means.


 * The SI brochure also has temperatures in the form (x±y) °C. Gene Nygaard 19:17, 7 November 2006 (UTC)


 * Note also that even your example didn't use "deg C". Consider also the rule expresed in the SAE guide, §7.3.3:  "The symbol °C for degree Celsius is treated as an entity; the two components ° and C are not to be separated."


 * Note also that both the SI brochure and the NIST guide SP811 list one, and only one, symbol for the degree Celsius: °C.  Gene Nygaard 19:25, 7 November 2006 (UTC)


 * Note also that BIPM and NIST go out of their way to point out that SI prefixes can be attached to °C. But let me clue you in on something; the m°C they use isn't ever going to be used to express a temperature reading.  It is only going to be used for a temperature interval.  Gene Nygaard 19:28, 7 November 2006 (UTC)


 * Here's the BIPM SI brochure, http://www.bipm.org/en/si/si_brochure/chapter2/2-1/2-1-1/kelvin.html
 * "The unit of Celsius temperature is the degree Celsius, symbol °C, which is by definition equal in magnitude to the kelvin. A difference or interval of temperature may be expressed in kelvins or in degrees Celsius (13th CGPM, 1967-1968, Resolution 3)."
 * Note carefully—there is one and only one symbol given there, not two of them. Gene Nygaard 19:33, 7 November 2006 (UTC)


 * Jeez you can be arrogant. Wikipedia is no place for personal attacks like I "don't know what the word 'abrogated' means.” If you can't learn this simple rule of etiquette, then get out of Wikipedia until you cool off. The relevant issue is what is the proper way one is supposed to write a temperature interval according to the international standards body that governs this sort of thing. The Web is chock full of documents written by all sorts of otherwise authoritative sources (like NASA). Ultimately, these documents are written by engineers and scientists that were never given a class on how to format temperatures (or forgot it). Res 3 and Res 7 are clearly written as to the proper way to denote temperatures and intervals. As I've already written, I've e-mailed the ex-head of the BIPM to see who's reading these resolutions correctly.  Greg L 19:42, 7 November 2006 (UTC)


 * Just asking. Do you know?  You still didn't answer.  And whether you do or not is very much relevant to the question of whether or not you can correctly usderstand the CGPM resolution.
 * Remember WP:NOR, any original research on your part isn't relevant in any case. You need verifiable sources, and none of the world's real experts in metrology see things through the distorted glasses you are using.
 * Just how damn many examples do you need? Here are some more:


 * http://www.bipm.org/utils/common/pdf/its-90/TECChapter10.pdf "and ± 2 °C at 1500 °C"
 * http://www.bipm.org/utils/common/pdf/rapportBIPM/2003/09.pdf "the water temperature was stable to better than 0.02 °C at the VNIIFTRI."
 * http://www.bipm.org/utils/common/pdf/rapportBIPM/2004/04.pdf "Note that only the differential temperature appears in (1) so that the units may be either °C or K."
 * "thermal coefficient of order –200 × 10-6/°C,"
 * "The second temperature reading is always about 2 °C below the first."


 * Enough yet? There are, of course, still a lot more that could be listed. Gene Nygaard 19:51, 7 November 2006 (UTC)


 * Gene: Resolution 7 in 1948 decided the following:


 * "To indicate a temperature interval or difference, rather than a temperature, the word "degree" in full, or the abbreviation "deg" must be used." Resolution 3 in 1967 decided as follows:


 * decides
 * 1) the unit of thermodynamic temperature is denoted by the name "kelvin" and its symbol is "K";
 * 2) the same name and the same symbol are used to express a temperature interval;
 * 3) a temperature interval may also be expressed in degrees Celsius;
 * 4) the decisions mentioned in the opening paragraph concerning the name of the unit of thermodynamic temperature [stuff related to "degree Kelvin" and °K], its symbol and the designation of the unit to express an interval or a difference of temperatures are abrogated, but the usages which derive from these decisions remain permissible for the time being.


 * Gene, there's no point citing improper usage. The issue is what is the proper way to denote an interval as determined by formally adopted, internationally recognized resolutions. Resolution 7 is in black & white. Nothing in Resolution 3 reversed that. Greg L 20:15, 7 November 2006 (UTC)


 * The 1948 Resolution 7 was "abrogated". It really is that simple.


 * Gene, You are misreading Resolution 3. Res 3 is quite clear; It abrogated only the part regarding °K and "degree Kelvin".   Greg L 21:07, 7 November 2006 (UTC)


 * The CGPM doesn't pretend to provide all the details of usage. The primary standard in that regard is the one the BIPM defers to as well, namely ISO 31.  I don't have, or have access to, ISO 31, but I'll bet that it does not in any way sanction use of "deg C" for degrees Celsius, unless maybe it is on an all-ASCII Usenet forum or mailing list or something along those lines.  Gene Nygaard 20:52, 7 November 2006 (UTC)

Greg L wrote above "The Web is chock full of documents written by all sorts of otherwise authoritative sources (like NASA). Ultimately, these documents are written by engineers and scientists that were never given a class on how to format temperatures (or forgot it)."

However, none of the examples I gave were from NASA. They were all from the web pages of the BIPM. Gene Nygaard 15:17, 9 November 2006 (UTC)


 * I think I agree with Gene on this. There is a note in http://www.bipm.org/en/CGPM/db/9/7/ that says "The CGPM abrogated certain decisions on units and terminology, in particular: micron, degree absolute, and the terms "degree", and "deg", 13th CGPM, 1967" (emphasis added), and a note in http://www.bipm.org/en/CGPM/db/13/3/ that says "At its 1980 meeting, the CIPM approved the report of the 7th meeting of the CCU, which requested that the use of the symbols "°K" and "deg" no longer be permitted." (emphasis added). Also note that the "opening paragraph" of resolution 3 in 1967 (the one referred to by the abrogation in decision 4) not only includes °K, but also "deg" and "degree". --Itub 19:13, 9 November 2006 (UTC)


 * Itub: Resolution 3 was addressing strictly the issue of °K and degree kelvin, which became symbol K and kelvin. Greg L 19:27, 9 November 2006 (UTC)


 * But what do you say of the notes I cited, which explicitly refer to the abrogation of the terms "deg" and "degree"? Granted, the notes don't seem to be part of the official resolution, but they were added by someone at the BIPM, who I would hope is well-informed regarding the accepted interpretation of these resolutions. --Itub 19:37, 9 November 2006 (UTC)


 * : Jeez Gene, you sure have a lot of energy don't you? I see from your contributions, that you merrily write what appears to be hundreds of edits every day on lots and lots of articles. Unfortunately, you don't invest the huge number of hours it takes to focus on a single, fluid article. You do all the fun stuff: quick corrections and then skip off to some other article. From what I can see, your corrections are for the most part, correct and sorely needed.


 * But you and I last butted heads on this Celsius article over whether or not the term "Celsius" was historically used in the 18th and 19th centuries before its 1948 adoption. You said Celsius was historically used. I asked if you found an an actual historical usage of "degree Celsius." I had read some actual scientific papers from the period. You responded "No. Merriam-Webster's Collegiate Dictionary" had a mentioning of the term dating to 1850. So what did I have to do? I exchanged literally dozens of e-mails with a guy—a Ph.D. no less—who headed the BIMP for twenty years and I also referenced his books and papers. I wrote versions of the history of the naming of the Celsius scale and posted them in less-visible areas of Wikipedia and Dr. Quinn read them and commented on them (and I fine-tuned them) until he was satisfied. Then I posted them on this Celsius article. I also twice drove to my local library to look at what the current Oxford English Dictionary says about Celsius and also looked at what the 1933 edition of OED said about Celsius (not a thing, no entry at all).


 * Eight days ago, I had to correct damage from some guy who "corrected" (see these changes) the Celsius article as well as ITS-90 and the Kelvin article. He wrote this in this Celsius article…


 * As with all metric unit symbols and all the temperature symbols, a space is placed between the numeric value and the symbol when the symbol begins with a letter (° is not a letter); e.g., “23°C” (not “23 °C” or “23° C”) and “296.15 K” (not “296.15K”).


 * He merrily pulled that one out of his butt and went on to other articles doing the same damage. I had to spend even more time finding sources (both the BIPM and the NIST) to cite in order to moron-proof that paragraph.


 * Today I've written the BIPM and asked them the following:


 * Is Note #3 of Resolution 7 of the 9th CGPM still in effect? This is the one that reads “To indicate a temperature interval or difference, rather than a temperature, the word ‘degree’ in full, or the abbreviation ‘deg’ must be used.”


 * Gene, it's real simple. If the BIPM says it's no longer a recommendation, I'll be the first one to yank out the verbiage you object to. Now you might call this "original research" but that's just a load of military-grade bullonium; it's spending time to locate and cite truly authoritative sources. You can contact them yourself at this contact page if you like. Or you can keep on doing drive-by shootings on this article while I slog through and do all the time-consuming background work trying to make sure a single article is done correctly for once. So damn many contributors just keep on parroting what they read elsewhere on the Net. This is especially true with historical facts where the Web is sparse on information. Unfortunately, many of the Web's "sources" are simply copying what Wikipedia says and all we've got is a vicious circle of misinformation.  Greg L 19:27, 9 November 2006 (UTC)


 * Itub has already cited you authorative sources showing you exactly how the authorative sources understand that 1967 resolution. Itub has already shown you exactly what the BIPM does say. You have not addressed that, nor any of the authorative sources I have cited. Please stop inserting your misreadings into the article. Gene Nygaard 19:59, 9 November 2006 (UTC)


 * Resolution 12 of the 11th CGPM and Resolution 7 of the 9th both had now-abrogated verbage about how the symbol for thermodynamic temperature was °K and the name was "degree Kelvin". Resolution 7 stated clearly what they were onsidering, which was the "°K" and "degree Kelvin" issue. Nothing in it abrogated Note 3 of Resolution 7 of the 9th CGPM. They decided in Resolution 3 of the 13 CGPM "that the unit of thermodynamic temperature and the unit of temperature interval are one and the same unit, which ought to be denoted by a single name and a single symbol." What they were saying is that the new symbol K (not °K) and the new name "kelvin" (not "degree kelvin") "are used to express a temperature interval" as well as a specific temperature. Although it may be "pretty to think so", they did nothing to address the degree Celsius when they wrote about "degree". Please stop inserting your misreadings into the article. You should be mature enought to abide by the BIPM's response to my inquiry asking them for a formal interpretation. I know I am willing to abide by their ruling. It could be that I'm wrong on this; I can see that Resolution 3 could be interpreted as being broader to apply also to Celsius. But there is also the possibility that you are wrong.  Greg L 21:06, 9 November 2006 (UTC)


 * No, Greg. That is not acceptable. You need to follow No original research and Verifiability. Your private communications, of course, if you get a reply, should help straighten you out, and even in the unlikely chance that your expert supported your interpretation, you could then ask him to lead you to some published, reliable information you could use here.
 * And, more importantly, it is not acceptable because you yourself have been deleting referenced, verifiable, reliable sources from this article. When it comes to reliable sources, you don't get any better than NIST Special  Publication 811, Barry N. Taylor, Guide for the Use of the International System of Units (SI), which says right out in section 8.3 Temperature interval and temperature difference:  "the numerical value of a given temperature interval or temperature difference whose value is expressed in the unit degree Celsius (°C) is equal to the numerical value of the same interval or difference when its value is expressed in the unit kelvin (K)".
 * In this particular case, you first have the credentials of the author himself, Dr. B.N. Taylor (more below). But it is more than that; this is an official publication of the national standards laboratory of the United States, not a private publication by Dr. Taylor.  It was also approved not only by his boss, the Director of NIST, but also by the Under Secretary for Technology and the Secretary of Commerce.  And even more than that, this NIST Publication is recognized as a leading guideline by other national standards laboratories such as National Physical Laboratory, UK and the international experts at BIPM.
 * Of course, Barry N. Taylor is not only a professional metrologist, a recognized expert in the field, but since you are to impressed by degrees, he has a Ph.D. in physics. Not only that, but like your retired BIPM expert, he has also served on the Consultative Committee on Units (CCU) of the CIPM, whose primary function is to advise the CGPM.  Dr. Taylor has also served on the SUNAMCO Commission (Commission on Symbols, Units, Nomenclature, Atomic Masses and Fundamental Constants) of the International Union of Pure and Applied Physics  (IUPAP).
 * Yet you deleted that published, verifiable, and reliable reference. That is not acceptable.  Gene Nygaard 13:22, 10 November 2006 (UTC)


 * Gene: Like I said, I would abide by whatever the BIPM said. I've received two responses. Bottom line: You are right! The symbol °C is perfectly kosher for expressing an interval. I now have the score 1 to 2 (the historical naming of Celsius for me, and en-dashes and intervals for you). Of course, you and I didn't have a lengthy, well-researched battle on the naming issue. I mention this only to take some of the sting out of this loss for me, and to (hopefully) insure some modicum of humbleness on your part. So far, I haven't caught you as being wrong on anything that you completely dug your heals in on. Notwithstanding my criticism of your style of "drive-by shootings" on articles (and not spending your time to work a single article until it is harmonious and reads smoothly), all your contributions on technical articles are sorely needed and very well done. From what I can see, your style of sweeping through gobs of Wikipedia space to correct errors is done in a way that doesn't discourage writers from spending lots of time writing an article as long as you have your opportunity to correct the numerous errors in facts, grammer, or punctuation.


 * I received responses from someone who currently works at the BIPM—Michael Stock—as well as the ex-head of the BIPM (Dr. Quinn). Both confirmed what you've been saying all along. I don't know why I had such a hard time finding a BIPM document which unambiguously stated how the symbol "°C" is suitable for use as an interval. Dr. Quinn kindly elaborated on the topic and pointed out a BIPM brochure (and specific page numbers as well) that supposedly directly addresses this issue and further, gives specific guidance on how use use the unit name "degree Celsius" and its symbol, °C, for expressing an intervals so as to avoid the ambiguity that can arise. I'm leaving for a business trip for four days. When I get back, I'll expand on the Intervals section to cover the BIPM's fully explicit recommendations for expressing intervals with "degree Celsius," °C, etc, as well as the associated note and citations. Greg L 17:45, 10 November 2006 (UTC)


 * Don't get carried away. It isn't anything that needs a whole lot of elaborating.  Keep it simple and encyclopedic.  If anything, trim away from what we already have, rather than adding to it.  Getting bogged down in trivial details doesn't help anybody's understanding.  Gene Nygaard 01:14, 11 November 2006 (UTC)

Temperature scales timeline?
Is there any article in wikipedia that lists all the temperature scales ordered by the date when they were proposed? If not, should we create one? (Or add it as a section to an existing article?) Itub 14:24, 16 January 2007 (UTC)

“100 divisons” in opening paragraph / “melting point” vs. “freezing point”
Mandel: Your recent edit to the Celsius article had several inaccuracies and needed to be immediately corrected. First, you had mentioned the "freezing point" of water. There is a difference between the melting point and freezing points of water. Although many people consider them to be the same, at the millikelvin level, they are different. Accordingly, precise thermometry experiments used to always use the melting point of water for defining the Celsius scale. Today, ITS-90 makes use almost exclusively of the melting points of various elements. The difference between the two is, of course, defined as whether heat is going into the sample during the measurement (melting) or is going out of the sample (freezing). Secondly, the Celsius scale is only approximately 100 divisions between the melting and boiling points. This is an old, outdated definition; since 1954, the Celsius scale has been defined by two entirely different points. As a result of this new definition, there are, today, only 99.9839 degrees between the melting and boiling points of water. The proper definition of the Celsius is precisely covered by the very next paragraph of the article. There is certainly no need for an outdated and scientifically incorrect "definition" immediately before the paragraph that gives the proper one. Your effort at getting the value "100" into the article may be well-intentioned, but can certainly wait for the very next paragraph, which properly addresses the issue by stating as follows:


 * “Until 1954, 0 °C on the Celsius scale was defined as the melting point of ice and 100 °C was defined as the boiling point of water under a pressure of one standard atmosphere; this close equivalency is taught in schools today.”

Also, Anders Celsius's contribution is overstated when one writes that he developed “the prototype” of the scale. Celsius developed a backwards version of the scale where zero was the boiling point! Accordingly, it's more accurate to state that he developed a "similar" scale. The contribution you made appears that it may have come right out of a textbook of some sort. However, the textbook you chose seems to have been geared to a scientifically entry-level reader and, unfortunately, has several errors and inaccuracies. It was certainly not an encyclopedic resource. Please delete this message at your next convenience. Greg L 04:54, 25 January 2007 (UTC)


 * Hi,


 * There is no inaccuracy. The scale I described in para 1 was the original centigrade scale devised by Anders Celsius, which does use the two points - freezing and boiling points of water - to calibrate 100 equal intervals between them.  As for whether Celsius's contribution is overstated, I don't think Christin has done much different either, merely the numeric inversion of the scale; Celsius's concept was fundamental and earliest and hence 'prototype'. This was clearly what the SI committee thought too, or his name wouldn't be feted thus.


 * Most textbooks still define Celsius thus; for simplicity of understanding, almost every college textbook gives the old definition first, then the revised one. As it stands the article's lead is overly technical and certainly too hard to understand for a non-scientific reader; to grasp a concept of Celsius you must first understand kelvin, triple point of water, absolute zero etc and the unwieldly number[s] 273.16 / 273.15.  These concepts really came into play after 1954.  But the 100-interval thermometric prototype was after all still what the kelvin and its current definition are painstakingly based on.


 * I did not refer to any textbook; the rewrite was based entirely on the wikipedia text itself. Maybe we can come to a compromise. Cheers. Mandel 09:09, 25 January 2007 (UTC)


 * Mandel: “But the 100-interval thermometric prototype was after all still what the kelvin and its current definition are painstakingly based on.”: That statement is not true. The definition of the kelvin and the Celsius are not based on one hundred divisions based on boiling and melting points. Below the errors are highlighted with underlines and bolding:


 * The Celsius temperature scale (previously known as the centigrade scale) is named after the Swedish astronomer Anders Celsius (1701 – 1744), who developed the prototype two years before his death.undefined The scale divides the freezing and boiling points of pure water at standard atmosphere pressure into one hundred equal intervals - each unit corresponding to one degree Celsius (symbol: °C).


 * 1) The scale is not currently not based on the melting and boiling points of water; it used to be so it is incorrect to say this.
 * 2) The melting point never was what you called the "freezing point." There is a difference at the mK level.
 * 3) Anders developing "the prototype" carries the connotation that he was the first to develop the scale. His was a backwards version so the only thing in common to the version used before 1954 is that it had 100 divisions. Accordingly, saying he developed a "similar" scale is more accurate.


 * Please do not revise until you have a solid understanding of precisely what the degree Celsius is, the Celsius scale, and their modern definition. There can't be "compromise" with statements that are factually incorrect. Greg L 20:23, 25 January 2007 (UTC)
 * I think you'd better cool down and read what I wrote to you carefully. I've reworded my edit for clarity.


 * The Celsius temperature scale (previously known as the centigrade scale) is named after the Swedish astronomer Anders Celsius (1701 – 1744), who developed a similar prototype scale two years before his death. His calibration divides the freezing point and boiling point of pure water at standard atmosphere pressure into one hundred equal intervals - each unit corresponding to one degree Celsius (symbol: °C).
 * Clear? There is nothing inaccurate or contradictory about this.  I'm talking about Anders' original definition, not the SI committee's. Did Anders use the freezing point?  I don't know, but he did write a paper on this, didn't he?  It should be easy to check this out.  Every resource I found states he used the freezing point.
 * Prototype - An original type, form, or instance serving as a basis or standard for later stages.; something analogous to another thing of a later period; An original model on which something is patterned on. Isn't Anders' scale what we base the centigrade scale on? The word 'prototype' does not imply a 100 per cent likeness.
 * Please don't condescend. If anything is misleading me it's Wikipedia, not a pre-1954 textbook. I hate to use boldings, but if it helps one to clarify myself, I would. Mandel 22:19, 25 January 2007 (UTC)


 * I am cool. And I won't be baited with an insinuation that I'm not. What you had was simply scientifically incorrect. It got deleted and you're still trying to defend it. I'm simply calling it like it is. I simply will not yield to factual inaccuracies masquerading as clarifications because an author is looking out for the type of "non-scientific reader" who can't understand this article because they'd first have to "grasp concepts" such as "unwieldily numbers [like] 273.16 / 273.15." Note that the actual "unwieldily number" you must be referring to is "1 part in 273.16 parts": a simple fraction. Sometimes scientific rigor must be sacrificed to explain advanced thermodynamic concepts in an understandable way. This article clearly doesn't fall into that category and can be fully well explained in an encyclopedic, completely factual way as long as the goal isn't to dumb it down for readers who can't understand fractions!


 * Now that you've clarified what you meant (vs. what you actually wrote) the resulting product is simply a historical account of the Celsius scale and what Anders Celsius kinda sorta first did (100 divisions but backwards). Indeed, this is the only valid way of salvaging your goal of writing that the Celsius scale is 100 degrees between the melting point of water and its boiling point. It used to be, but no longer. The concept of "100 divisions" is completely and accurately addressed in the very first sentence of the next paragraph. The article even has an entire section on the "100 divisions" issue titled “The melting and boiling points of water”. The actual number of degrees separating the melting and boiling points is 99.9839 °C, not 100. Your revised wording belongs in a history section, not in the opening description of what the word Celsius means. Give it up.


 * And even your revised proposed wording still doesn't properly address the "freezing point" vs. "melting point" issue; what you propose is still incorrect. Note that in the time of Anders Celsius, no one had little refrigeration units to freeze water samples. Even during the summer months, people of this period had icehouses wherein straw served as an insulating blanket for ice blocks that had been cut from lakes during the winter. Physicists at the time crushed up the ice and mixed it with water to make a coarse-grained slush. The ice had already been formed. External heat leaking into the slush slowly melted the ice particles and increased its water fraction. Thus, temperature measurements were made at the melting point (which is a much more reproducible temperature point than the freezing point because the supercooling effect occurs all the time at the millikelvin level). The above-described “slush” technique (172 kB) provides a stable, long-lasting temperature source that is extremely insensitive to how the probe is positioned within the sample. This is still the way it's done today in thermometry for practical deliniations of the Celsius scale. I used this technique myself for the temperature-sensing circuit on a patented, electronic gas-density meter we were developing for the electrical utility industry.


 * This article is referenced on 44 foreign-language versions of Wikipedia and is considered as the authoritative, free reference source on technical topics like Celsius. There is zero room for inaccurate statements in this article. I am quite done debating you on this. If you can improve the article by making accurate, factually true, non-misleading statements, and do so in a way that is clearer than is what is currently here. Great. If you keep writing stuff that isn't up to the necessary standards, or tries to masquerade outdated and inaccurate definitions as something that they're not, don't be offended when it gets reverted. Greg L 00:09, 26 January 2007 (UTC)


 * The disinction made above between melting and freezing points struck me as a little odd, although it's implicitly supported by Melting_point. If that logic follows, though, how can it be possible to obtain a boiling/condensation point?  (Remembering that it is possible to both cool a vapour below the nominal value as well as heat a liquid above the nominal value.)
 * I would have allowed for the possibility that a liquid material can be cooled below its freezing point, where that parameter could be defined as equal to the melting point.
 * At Boiling point is written: A somewhat clearer (and perhaps more useful) definition of boiling point is "the temperature at which the vapor pressure of the liquid equals the atmospheric pressure.".  In this way m.p. can be the same as c.p..  So why not with f.p. and m.p.?
 * For my education, if nothing else, do you have any better references on this?
 * — DIV (128.250.204.118 09:38, 1 September 2007 (UTC))
 * I probably should add that I think reference to a m.p. is more common than to a f.p.; also, mention of a c.p. would have to be quite rare.
 * — DIV (128.250.204.118 09:45, 1 September 2007 (UTC))

Proposed WikiProject
Right now the content related to the various articles relating to measurement seems to be rather indifferently handled. This is not good, because at least 45 or so are of a great deal of importance to Wikipedia, and are even regarded as Vital articles. On that basis, I am proposing a new project at WikiProject Council/Proposals to work with these articles, and the others that relate to the concepts of measurement. Any and all input in the proposed project, including indications of willingness to contribute to its work, would be greatly appreciated. Thank you for your attention. John Carter 21:10, 2 May 2007 (UTC)

Unicode characters
Shouldn't you use the special Unicode characters, ie.: ℃ - one characater instead of ° followed by uppercase C, ℉ - one character instead of ° followed by uppercase F, K - not exactly the same character as uppercase K, throughout the whole article to add more meaning for machines accessing it? The exception could be paragraphs which describe how not to write degree Celsius (spacing). Are there any compatibility issues with default system fonts? Safari 2.0.4/419.3 on Mac OS X 10.4.9 displays it fine.


 * No, the ℃ exists in Unicode solely for round-trip compatibility with some East Asian legacy encodings that encoded this character. Recommended use is the combination of the two characters °C. Markus Kuhn (talk) 17:03, 30 January 2008 (UTC)


 * I think it's better to remove the paragraph about the Unicode compatibility character '℃' (and maybe just leave a small note somewhere). This character is not supposed to be used, so I don't see the point to have a full paragraph about it. Moreover the title ("The special Unicode degree Celsius character") may lead to think that this is the special character that one should use instead of '°C'. —Preceding unsigned comment added by 130.232.126.213 (talk) 03:35, 11 March 2009 (UTC)


 * If someone were having trouble figuring out what the Unicode degree Celsius character was all about, there is a good chance they would look at this article. Whether it should be used is really beside the point; if it is used, where will someone look for help? --Jc3s5h (talk) 04:12, 11 March 2009 (UTC)

The melting and boiling points of water
This section contains the statement: "Thus, the actual melting point of ice is very slightly (less than a thousandth of a degree) below 0 °C." However, Vienna Standard Mean Ocean Water, to which this article links, says: "Thus, the actual melting point of ice is +0.000 089(10) °C." I am noting this descrepency here as I do not know which is right, and there are no citations in either location. Jjamison 20:18, 11 June 2007 (UTC)

I have a different question about this section. It seems that what should be identical information is included both in this section and in the Use in temperature standards section of the Vienna Standard Mean Ocean Water article. Whenever the same information is repeated in any database, there is always the possibility for that information to become inconsistent. My question is this: How can duplicated information be included in two articles in such a way that only one editable copy exists? Or is it preferable to have that information in one article only and have the other article include only a "see" reference? Howard McCay (talk) 08:51, 22 December 2010 (UTC)

Centigrade
"For lay-people worldwide — including school textbooks — the full transition from centigrade to Celsius required nearly two decades after this formal adoption." Only two decades (taking us into the 1960s)? I wouldn't be so sure about that! In primary school in the 1980s our teachers in England were still calling it Centigrade. -17:45, 20 August 2007 (UTC)
 * When I was doing teaching-practice in English primary schools in the 1990s the term "centigrade" was the only one used. In my experience today (2007) the word "celsius" is rarely heard, whilst "centigrade" is still the norm.  Timothy Titus Talk To TT  06:39, 25 November 2007 (UTC)

I agree. Celsius is often only used by those who do weather forcasts or those who are being scientific whereas the general public tend to use centigrade; especially the older generation as this generation were more used to using it than modern youths who are taught "celsius". Often American scientists say "centigrade" as they are more used to using Fahrenheit.Talk To TT  ' 19:50, 29 January 2008 (UTC) —Preceding unsigned comment added by 84.13.169.44 (talk)

Lead Section
It really needs some work. Way too long. I am a lemon 23:58, 27 August 2007 (UTC)


 * Agree.
 * The paragraph
 * This definition fixes the magnitude of both the degree Celsius and the unit kelvin as being precisely 1 part in 273.16 parts the difference between absolute zero and the triple point of water. Thus, it sets the magnitude of one degree Celsius and the kelvin to be exactly equivalent. Additionally, it establishes the difference between the two scales’ null points as being precisely 273.15 degrees Celsius (−273.15 °C = 0 K and 0.01 °C = 273.16 K).
 * should be moved or cut.
 * Likewise the second, "key temperatures" table could be moved ...at the least to the RHS, where it would probably look less cluttering.
 * Overall there is too much talk about the kelvin in the lead-in to an article that is supposed to be about the degree Celcius!
 * — DIV (128.250.204.118 08:19, 1 September 2007 (UTC))   { I am not a lemon ... ;-) }

Popular misuse
The article currently has: Often in modern days, the word "degrees" is often missed out for example on the BBC weather, the forecaster may read a temperature as "30 celsius" as opposed to "30 degrees celsius". I would change this to something more concise, and also add mention of misuses of the symobol, e.g..: Modern news reports often omit (or 'ellipt'?) the word "degrees", such as in a forecast temperature of "30 celsius" instead of "30 degrees celsius". Indeed, for reasons of æsthetics, brevity, ignorance or technical limitations temperatures are often incorrectly written in the form "30C" or "30 C" instead of "30 °C". ...either that or remove it altogether. — DIV (128.250.204.118 08:01, 1 September 2007 (UTC))

And see also above at Talk:Celsius/Archive 1 —Preceding unsigned comment added by 128.250.204.118 (talk) 08:49, 1 September 2007 (UTC)

Did not SI define Celcius as a secondary unit without degrees? That is, the BBC is correct to describe the temperature as 10 C and not 10 °C. —Preceding unsigned comment added by 82.210.237.30 (talk) 12:16, 23 October 2007 (UTC)


 * No, degree Celsius is the official name of the unit and °C the official symbol. Markus Kuhn (talk) 17:00, 30 January 2008 (UTC)

Magnitude?
I found this portion of the article that said "the magnitude of the Celsius scale is exactly that of the kelvin scale". Would it be prudent to add the expression Δ °C = Δ K afterwards, to symbolize rate of change? ZtObOr 02:32, 30 January 2008 (UTC)
 * No, that is just an ambiguous ad-hoc notation. Better write a complete English sentence that clearly explains what you want to say, like "A temperature difference of 1 °C is the exactly same as a temperature difference of 1 K". Markus Kuhn (talk) 16:57, 30 January 2008 (UTC)

First sentence
The first sentence needs some TLC - it doesn't read properly. I'm not sure what to write though. Jake the Editor Man ( talk  ) 21:31, 13 February 2008 (UTC)

Formatting
The formatting section on this page appears to conflict with the formatting section on the "Degree Symbol" page.

Quoted from the Celsius page: The general rule is that the numerical value always precedes the unit, and a space is always used to separate the unit from the number, e.g., “23 °C” (not “23°C” nor “23° C”).

Quoted from the Degree Symbol page: However, in many professionally typeset works, including scientific works, such as those published by The University of Chicago Press or Oxford University Press, the degree symbol is printed with no spaces between the number, the symbol, and the C or F representing Celsius or Fahrenheit, as in "10°C".[3] This is also the practice of the University Corporation for Atmospheric Research which operates the National Center for Atmospheric Research.

--208.251.98.18 (talk) 17:51, 18 June 2008 (UTC)rymzon


 * I believe the spaced version is correct. The FAA, for example uses “23 °C”, and not “23°C” (or "F").  But I, as a technical writer, find it extremely tedious to be typing the degree symbol (Alt-0176) repeatedly, and then having to wrestle the final output through the publishing software, and then proof-reading every character in case the software trips up and produces "23•". Most scientists I know will simply say "23C" in informal correspondence to save a lot of itch. When publishing, I switch the Alt-0176 for a superscripted lower-case "o".  Is there much difference between difference between 23° and 23o?  Nobody's complained yet. But I'd love to see the symbol changed to a simple "C" before I go to my grave. Alt-0176 is a real pain in the internet age. Santamoly (talk) 05:49, 27 September 2010 (UTC)

Centigrade is not the same as Celsius?
I was always taught that Centigrade and Celsius were not the same, yet this article says that they are. The difference I was taught was in how their two definition points were different. Centigrade came first (and post-inversion) the scale had the freezing point of water defined as 0 degrees Centigrade, and the boiling point of water defined as 100 degrees centigrade. These were true by definition - as the temperature of these were found with more accuracy the point 0 centigrade was still waters freezing etc (only the relationship with other scales would have changed). Thereby creating a scale with 100 graduations between freezing and boiling. Then after the introduction of Kelvin; a new different scale was created called Celsius whose definition points were Absolute zero being -273.15 Celsius and The freezing point of water being 0 celsius. This means that the two scales are similar - 1 degree Centigrade being 1 degree Celcius, but they are different due to the different points used in defining the scale. Was I taught wrong all the time, despite gaining a UK A-Level in Physics (even if that was quite a few years ago now) 84.65.2.108 (talk) 15:11, 10 May 2009 (UTC)

Temperatures and Intervals
If my memory serves, when I was studying engineering in the 1960s, it was common practice to express temperature intervals as "Celsius degrees" (C°), rather than "degrees Celsius (°C), but I cannot now find anything on the web about this. Did that convention actually exist, and was it changed? Peter Chastain (talk) 12:33, 10 June 2009 (UTC)

I don't remember this from studying engineering in the 70's. However, it's a really neat idea, since "temperature interval" is a different physical quantity to "temperature" and therefore deserves to have a separate name and separate symbol. Right now they are treated as the same unit in the SI, but technical software such as Mathcad and Mathematica implement them as different units. Adamtester (talk) 00:59, 22 September 2009 (UTC)

I'm studying engineering right now, and one of my textbooks still does it. Maybe someone with more writing skills than me could add it to the article?

Never mind, I made the edit.

--FrederikVds (talk) 01:59, 1 June 2011 (UTC)

unclear sentences
I don't understand the following sentences:

"The 'degree Celsius' has been the only SI unit whose full unit name contains an uppercase letter since its SI base unit, the kelvin, became the proper name in 1967 for the obsolete term, the 'degree Kelvin'. The correct plural form is 'degrees Celsius'."

and I don't think it's me. Myles325a (talk) 02:35, 17 November 2009 (UTC)


 * For most names of SI units (at least in English) the name is never capitalized; for example, power is measured in watts. Many units are named after famous scientists, such as James Watt. For those units that are named after scientists, the symbol is capitalized; for example, the symbol for watt is "W". The degree Celsius is, in part, an exception; the name of the scientist is capitalized in the name of the unit. It is also unusual in that it is a two-word name.


 * I imagine it was not changed to "celsius" because the unit symbol "C" is already in use for the coulomb. --Jc3s5h (talk) 02:43, 17 November 2009 (UTC)

OP myles back. Ok, this is getting better, but still unclear. To say that "most names of SI units" [are] "never capitalized" is an oxymoron. And your explanation doesn't clear up what all that stuff about 1967 has to do with price of eggs in China. If you can understand it, please make an attempt to turn it into English. As I said, I don't really want to have it explained to me, I want it cleared up so everyone can understand it. At the moment, it is grammatically and stylistically a cracked bowl of alphabet soup. Myles325a (talk) 03:01, 17 November 2009 (UTC)

Google
In the example that "(1 degree Celsius) plus (1 degree Celsius) = 275.15 degrees Celsius", it is not unexpected if you understand how it works. Addition is defined over Kelvin temperatures, in the same way addition can be defined over integers or real numbers. Addition over Kelvin is different to addition over Celsius due to the different zero (additive identity) element.

As for its suitability for Wikipedia, the link is directly to a primary source without a non-Wikipedia-based explanation of its significance (thus original research). I've removed it. 118.90.87.154 (talk) 02:19, 22 February 2010 (UTC)

"From 1743 until 1954, 0 °C was defined as the freezing point of water and 100 °C was defined as the boiling point of water, both at a pressure of one standard atmosphere with mercury being the working material. Although these defining correlations are commonly taught in schools today, by international agreement the unit "degree Celsius" and the Celsius scale are currently defined by two different temperatures: absolute zero, and the triple point of VSMOW (specially purified water). This definition also precisely relates the Celsius scale to the Kelvin scale, which defines the SI base unit of thermodynamic temperature with symbol K. Absolute zero, the lowest temperature possible at which matter reaches minimum entropy, is defined as being precisely 0 K and −273.15 °C. The temperature of the triple point of water is defined as precisely 273.16 K and 0.01 °C.[2]"

This is not as clear to the reader as it could be in telling them the measurement standards for 0 degrees Celsius as they are used today — Preceding unsigned comment added by Banthablaster (talk • contribs) 03:00, 5 October 2012 (UTC)

Conversion Table
Does the conversion chart with half a dozen or more different temperature scales belong in this article or in the article temperature? I think that it belongs in the article temperature. Martinvl (talk) 21:03, 13 April 2010 (UTC)

Thermometer picture incorrect?
It appears that the thermometer in the picture is incorrect as -40 C and -40 F (the point at which Celsius and Fahrenheit are the same) are not in line. Am I just reading it wrong? —Preceding unsigned comment added by Darktangent (talk • contribs) 01:19, 24 April 2010 (UTC)


 * Maybe it is an imperfect thermometer, or maybe it is parallax. --Itub (talk) 14:26, 24 April 2010 (UTC)

Use of Centigrade
This article is somewhat misleading in it's presentation of "Centigrade" as no longer used. This occured to me recently when watching TV News - in two separate news items "Centigrade" was used in statements given by English speaking government representatives. I'm not suggesting any serious changes except perhaps to note that "centigrade" is still in wide use in the English speaking world as a vernacular term. My feeling is that "Celsius" hasn't caught on with "the man in the street". 122.107.58.27 (talk) 05:54, 24 April 2010 (UTC)


 * You don't say which country you are from, but in Canada the term "Centigrade" is rarely used in popular media. It's "Celsius", everywhere. If any shortening is done, the mention of the "C" variants is omitted, and the temperature is be given as "degrees" only. So the article is correct - in Canada. Santamoly (talk) 16:21, 3 May 2010 (UTC)

Where I'm from isn't really important, the use of "centigrade" I was referring to were by British and American politicians and were seen on TV news reports on Australian TV. I don't doubt that "Celsius" is used, I am suggesting that "Centigrade" is also widely used in the English speaking world (except Canada). I guess I am saying that the statement '"Centigrade" as no longer used' is an uncited statement. 122.107.58.27 (talk) 22:24, 17 May 2010 (UTC) So please do not lump Australian and New Zealand speakers into the same group as British and American speakers (who both tend to still use imperial measures in common language). --124.179.215.119 (talk) 02:25, 26 July 2013 (UTC)
 * In Australia and New Zealand, we are the same as those in Canada in that we use the term 'Celsius' exclusively, and rarely ever use the term 'Centigrade'. The term 'Centigrade' is very rarely used in common language and the term is never taught in our schools, therefore the preferred term of 'Celsius' is taught in our schools exclusively.

I noticed someone changed "celsius" to "centigrade" in the Sheffield Winter Garden article, so I came here to see if that was appropriate. The article still suggests that "centigrade" is rarely used. If that's not the case, the article should not make that claim. Reach Out to the Truth 17:48, 13 June 2010 (UTC)


 * Celsius was adopted by the world community in 1948 to preevent confusion with the French angular measure - centigrade (=1/10000 of a right angle). Martinvl (talk) 17:56, 13 June 2010 (UTC)


 * "Celsius" is correct, and is in fact the term used on the city council's own web page about the Winter Garden. I reverted the change you noticed, with a suitable edit summary; hopefully, that'll be enough. Thanks, Hqb (talk) 18:00, 13 June 2010 (UTC)

Prominence of Conversion Section
When I first loaded this page, I scrolled down to look for conversion factors from Fahrenheit to Celsius, but couldn't find them. I scrolled back up to the top, and it was only then that I noticed the conversion factor table, which was all the way in the top right corner. This means that readers who, like me, assume that the information would be prominent enough that it would in the article, not in the corner of the screen, where is is "out of the way" and less likely to be noticed. Aero-Plex (talk) 18:18, 10 November 2011 (UTC)

Coexistence of Kelvin and Celsius scales
I have read the following sentence more than ten times: "Notwithstanding the official endorsement provided by decision #3 of Resolution 3 of the 13th CGPM, 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 world as the use 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." My English is far from perfect (my native language is Swedish), but it is not that bad and I'm not extremely stupid - however I still do not understand what I supposedly should understand from the the above writing. My guess is that "as the use" should be something like ", while the use"... --Episcophagus (talk) 01:57, 2 November 2012 (UTC)

Lede picture
Is the thermometer in the lede calibrated in degrees Celsius? Is the sky blue?

This thermometer was photograpjhed by a German photographer and looks like any thermometer that is sold by the thousand across Germany. Since degrees Celsius is the only temperature scale used in Germany (apart from Kelvins in scientific work), they often do not incorporate "°C" intio the design. Martinvl (talk) 06:49, 14 December 2012 (UTC)


 * You make many risky assumptions there. That "German photographer" (how do you know that?) may have taken the photo in the US, or anywhere else. Why not avoid the speculation and leave the units unsaid? Curatrice (talk) 11:16, 14 December 2012 (UTC)


 * If you double-click on the photo you will see the following text (which is in German):
 * Beschreibung: Thermometer
 * Quelle: selbst fotografiert, Juli 2003
 * Fotograf oder Zeichner: Muns
 * If you look at other works by the same photographer, you will see a very strong bias towards Germany.
 * Martinvl (talk) 11:49, 14 December 2012 (UTC)


 * As I said, risky assumptions, and apparently based on flimsy logic. I can speak and write English, but I'm not English. I looked at the other photos and saw many which were clearly taken outside Germany, and this one gives us no clues about its location. We can guess the units, but is that goos enough for Wikipedia? I don't think so. Curatrice (talk) 12:00, 14 December 2012 (UTC)


 * Do you have an alternative hypothesis regarding this picture? Martinvl (talk) 12:45, 14 December 2012 (UTC)


 * As I understand it, we aren't supposed to hypothesize, we are supposed to simply relay verifiable information. And, that is why I favour leaving speculation out of the image caption. The units don't really add any value in the given context - or do you disagree? Curatrice (talk) 13:03, 14 December 2012 (UTC)


 * This article is about degrees Celsius. Therefore any illustration shoulD show something to do with degrees Celsius. The evidence in favour of this being a thermometer that is calibrated in degrees Celsius is overwhelming.  If you look at the photograph in the lede of the article Metric system you will see a thermometer that has °C engraved on its face.  That thermometer is currently in front of me as I type (I took that photo).  Are you really asking me to go out and photograph it?  It is dull and raining outside and the picture will be poor. Martinvl (talk) 13:17, 14 December 2012 (UTC)


 * It's okay now, I found one clearly marked with a "C", so we don't need to rely on speculation, guesswork or hypotheses, and you can stay in the warm and dry too! Although why you have to go outside to take photos isn't apparent to me. Curatrice (talk) 19:43, 14 December 2012 (UTC)

This sentence does not make sense:
"Since the 19th century, the scientific and thermometry communities worldwide referred to this scale as the centigrade scale."

In my mind, "Since the 19th century" means "from (and including) the 19th century until today". This is incompatible with the past tense of "refer". "Communities worldwide referred to this scale as...since the 19th century"? This doesn't make sense. We ask the question: "When did communities refer to this scale as the centigrade scale?". The answer will be a time period (not merely a starting point!), such as "from the beginning of the 19th century until recently"; even "for a long time" or "until " would be acceptable. — Preceding unsigned comment added by 83.248.98.11 (talk) 12:04, 16 October 2013 (UTC)

1954?
The second paragraph of the article at hand begins with, "From 1744 until 1954, 0 °C was defined as the freezing point of water and 100 °C was defined as the boiling point of water ..."; nothing too controversial here, but neither the paragraph in question nor the entire article ever gets around to explaining what definitional change was effected in 1954. What happened then - was 0° C redefined as the freezing point of Tanqueray? Was 100° C redefined as the best temperature at which to fry a pork chop? We're left hanging. Such a prominent statement needs to be followed-up on or re-worded; as it is it's annoying and tends to send people like me on unsatisfying, irritating wild-goose chases - not the kind of response Wikipedia seeks to engender I suspect. BLZebubba (talk) 08:03, 22 October 2015 (UTC)

Regarding the "Melting" point of water... Water does NOT melt! Melt means to turn liquid and water is already a liquid. ICE melts, WATER freezes!

Assessment comment
Substituted at 11:08, 29 April 2016 (UTC)

Celsius equals gradians, not degrees?
While Fahrenheit and Rankine measure degree difference, doesn't Celsius and Kelvin actually measure gradian difference? The difference between the freezing and boiling points of water in Fahrenheit and Rankine is 180, and in Celsius/centigrade and Kelvin is 100, thus Celsius/Kelvin uses the first trigonometric quadrant as the spread, in gradians (0-100ᵍ), while Fahrenheit/Rankine extends the spread out through the second quadrant, in degrees (0-180°). 216.57.137.169 (talk) 02:19, 9 July 2016 (UTC)
 * Yes, but remember, gradian equals "centesimal degree", so rather than confuse the masses with "20ᵍ" (20 gradians), it was decided that "20 °C" (20 {centesimal} degrees Celsius) be the formal description—though I imagine "20ᵍ" can be (and probably is) used in some (at least informal) situations, though I certainly wouldn't declare it in this article as formally acceptable, without any reputable sources. ~Kaimbridge ~  (talk) 23:01, 9 July 2016 (UTC)

Celsius measurement is that it follows an interval system but not a ratio system
'Celsius measurement follows an interval system but not a ratio system'. Is there any measurement that does follow a ratio system? If so, it should be added. Thanks in advance. Backinstadiums (talk) 18:37, 16 January 2017 (UTC)
 * The absolute scales use a ratio-based system to indicate the interval, if I'm reading that right. --Izno (talk) 13:23, 17 January 2017 (UTC)

why so insisting "degree" to be said?
simply we can say: it's 25 Ce[lsi(e)] (read /'selzi:/) {in the rhyme of Curie & Henry} and keep the deg[ron] and its sign as 1/360 of a revolution Tabascofernandez (talk) 21:29, 14 July 2017 (UTC)

Article title
This article would be better titled Celsius scale, with degree Celsius remaining as a redirect to it. The term "Celsius" does not properly have a meaning as a standalone term, and should perhaps be regarded as slang or shorthand. —Quondum 04:32, 16 July 2017 (UTC)
 * but Farad(-ay, Michael) and Volt(-a, Alessandro) and Bel(-l, Graham) properly have a meaning as a standalone term; or should be regarded as slang or shorthand?! even you may heard Neper (after Napier, John).

Tabascofernandez (talk) 01:18, 30 July 2017 (UTC)

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