Talk:Celsius

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Contents

[edit] 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)

[edit] 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)

[edit] 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...

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. JIP | Talk 07:18, 18 May 2007 (UTC)

[edit] Spelling: Celsius vs Celcius

Can someone explain the origin of the alternate spelling?

I note that the Oxford English dictionary now uses "Celsius", as do Americans and the man's name is "Celsius."

However, it was always "Celcius" when I was at school and University. I've checked with others and they recall being taught the alternate spelling. Perhaps "Celcius" is a better phonetic spelling for an english speaker?

Intriguing; never ran across that mistake(?) before myself. There are a lot of hits when you Google on it, too. Nothing in the Britannica or my other reference works. Must be another case of bloody American spelling.  :-)
Urhixidur 13:57, 2004 Nov 18 (UTC)
Enough of the gratuitous America-bashing. Back to your Google
         celcius site:.uk        13,800 hits
         celcius site:.au         7,450 hits
Gene Nygaard 05:51, 16 Feb 2005 (UTC)
There are some authors of books for schools and universities writing "Celcius", but I have found that my chemistry book for the university uses "Celsius". I think the last is the best way because of two reasons. First, it is fit with the English spelling. Then, it comes from the exact name of the Swedish scientist. Yves Revi 21:31, 27 October 2006 (UTC)
I think I've seen both too. However I think you've overlooked one obvious, important reason to prefer "Celsius", namely that it is the standard endorsed by the BIPM: see [1] or [2] (Incidentally, the latter clearly explains why Celsius is capitalised).
— DIV (128.250.204.118 08:40, 1 September 2007 (UTC))

[edit] 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

[edit] 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

[edit] 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)

[edit] 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—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))

[edit] 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)

[edit] 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—in addition to changing the name to kelvins—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)

[edit] "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.

--Earle Martin 13:36, 30 May 2005 (UTC)

[edit] 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").

[edit] 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)

[edit] 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"

[edit] 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)

[edit] 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)

[edit] 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)

[edit] 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)

[edit] 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))

[edit] 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)

[edit] When and by whom was the scale reverted?

I've been trying to find a reference for the fact that the scale was reverted, 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: Reverted in 1750 by Stromer or Linné.
  • Foundations of Engineering - Mark T. Holtzapple, W. Dan Reece: Reverted by Celsius himself in 1743.
  • Advanced Engineering Thermodynamics - Adrian Bejan: Reverted in 1747.
  • Applied Dimensional Analysis and Modeling - Thomas Szirtes: Reverted 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: Reverted by Celsius himself in 1743.
  • Temperature Measurement - L. Michalski, K. Eckersdorf, J. Kucharski, J. McGhee: Reverted by Stromer after Celsius's death.
  • The Merriam-Webster New Book of Word Histories - Merriam-Webster: Reverted 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: Reverted 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)

[edit] 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)

[edit] 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)

[edit] 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))

[edit] 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]


[edit] 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"

Table B1—APPLICATION OF SI UNITS
Quantity Typical Application From Old Units To Metric Units Multiply by(1)
Temperature interval General use °F K(5) 1 K = 1 °C = 1.8 °F*
Footnotes

1. An * indicates an exact conversion factor.
...
5. In these expressions K indicates temperature interval. Therefore K may be replaced with °C if desired without changing the value or affecting the conversion factor. For example: kJ/(kg·K) = kJ/(kg· °C).

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)

[edit] 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:
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 Wikipedia:No original research and Wikipedia: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:[3] "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)

[edit] 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)

[edit] “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.  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#Fundamentals. 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))

[edit] 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 Wikipedia:WikiProject Council/Proposals#Measurement 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)

[edit] 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)

[edit] 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)

[edit] 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)

[edit] 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 ... ;-) }

[edit] 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#.22Celsiheit.22_and_the_British_media —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)

[edit] 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)

[edit] 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)