Talk:Temperature conversion

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[edit] Leyden scale

Details are sketchy.

Introduced circa 1894? Leiden, Leide, Leyde or Leyden? Symbol °L?

The scale is supposed to be the Kelvin scale shifted so the boiling points of hydrogen and oxygen are zero and 70 respectively. For oxygen, the 1 atm boiling point is in the 90.15 to 90.18 K range. For hydrogen, it depends on the variety; it is 20.390 K for "normal" hydrogen [75% orthohydrogen, 25% parahydrogen] and 20.268 K for pure parahydrogen. Assuming that absolute zero is -20.15 °L is close enough and has the virtue of giving a round shift to the Kelvin and Celsius scales.

Urhixidur 22:47, 2004 Aug 16 (UTC)


[edit] Brackets

The new by Crissov invented brackets arround [°F] look crazy. What does that mean?

Smoky 10:50, 2005 May 11 (UTC)

I didn't invent them. It's not uncommon to enclose a unit symbol in square brackets for any value given in this unit, not the unit itself. Elsewhere the convention is to use a letter for the kind of the value (e.g. F for force, W for energy or T for temperature) and make the unit/scale an index of that, often by subscripts or round brackets. In HTML there is also an element type for variables, 'var', but in most circumstances it's just italic. So what shall we use in your opinion?
Kelvin
Celsius T°C = TK − 273.15 TK = T°C + 273.15
Celsius TC = TK − 273.15 TK = TC + 273.15
Celsius TCelsius = TKelvin − 273.15 TKelvin = TCelsius + 273.15
Celsius T(°C) = T(K) − 273.15 T(K) = T(°C) + 273.15
Celsius [°C] = [K] − 273.15 [K] = [°C] + 273.15
Celsius °C = K − 273.15 K = °C + 273.15
Maybe this is also a matter for the MoS.
I always forget when to use lowercase Greek theta (ϑ) or uppercase Latin tee (T) for temperature values. Christoph Päper 16:48, 11 May 2005 (UTC)
The first in your table is the best way I think. However, I prefer to use italics because it is a variable.
T°C = TK – 273.15
TK = T°C + 273.15
What do you think? Yves Revi 21:06, 28 October 2006 (UTC)

[edit] Plank

Let's add the Planck unit of temperature. Jimp 17Oct05

There are several Planck units and the only one related to temperature seems to be a constant. Which unit do you mean? --ZeroOne 09:40, 17 October 2005 (UTC)
I think Jimp means to add each scale's equivalent to the Planck constant. Hans404 03:38, 9 January 2007 (UTC)
T_P = \frac{m_P c^2}{k} = \sqrt{\frac{\hbar c^5}{G k^2}} as a unit. Jɪmp 08:46, 16 January 2008 (UTC)
However, I'm not so for it now ... in fact, I wonder whether there's much point to this page at all since Conversion of units covers the main four and on the article pages for each of these there's an info box with formulae and a nav. box with links to the articles on the other scales some of which have such infoboxes and others could easily have them added (I think I'll be doing this). Jɪmp 01:44, 24 January 2008 (UTC)

[edit] Brackets again

the use of the brackets is against the standard defined in ISO 31 - it's not wrong, but in Wikipedia we should not use them this way. The right way to use the brackets is:

[T] = °C

to say this: the unit of the T (Temperature) is °C (degrees Celsius) (well it should better say Kelvin, but °C shows it better here). It would be great, if someone could add a good explanation to ISO 31-0 (I just added a short sentence there). Greetings -- 217.84.150.117 01:14, 28 July 2007 (UTC)

[edit] Wiki conversion templates

There's a handy template to display the same temperate in two units, e.g. {{convert|18|°C|°F|1}} yields 18 °C (64.4 °F). Should be mentioned somehow in the articles to teach editors about their existence. Also, there are tables which have been subject to subtle changes, which could be avoided by using the template. -- Matthead discuß!     O       01:03, 30 September 2007 (UTC)

It'll do three, even four, (e.g. {{convert|18|C|K F R}} yields 18 °C (291 K/64 °F/524 °R)) but the article space is not the place to talk about templates. Jɪmp 14:34, 24 January 2008 (UTC)

[edit] Incorrect conversion formulas

The conversion formulas on this page are incorrect, as are ALL the temperature conversions throughout various pages, for Réaumur and Rømer. The "273.13" in each of these forumlas should actually be "273.15" since this is the correct Kelvin value for 0˚C. As it stands, a conversion from Celsius -> Kelvin -> Réaumur gives an incorrect conversion from 0˚C to 0.016˚Re. Similar inaccuracies occur with Rømer conversions. I would change them all myself, but I'm not sure where to. Sbrocket (talk) 04:36, 11 March 2008 (UTC)

I noticed that. For example, this is wrong
Celsius [℃] = [K] − 273.15 [K] = [℃] + 273.15
Because Celsius clearly is not Kelvin minus 273.15 degrees. That would mean the Celsius scale is below absolute zero? (86.2.105.34 (talk) 16:19, 15 March 2008 (UTC)):
No, 0˚C = 273.15K. That is the correct conversion for Kelvin to and from Celsius. Absolute zero on an absolute temperature scale such as Kelvin or Rankine is defined as 0 degrees on that scale. Absolute zero in Celsius is -273.15˚C, since this is 0K. My comment above still stands, however - the conversion formulas are incorrect since "273.13" is used rather than "273.15". Sbrocket (talk) 17:08, 26 March 2008 (UTC)

[edit] Image to table

We should remake the table image as a proper table. I'll lay the basis here. Please continue to fill it out. (Checking for errors is also good.) —Bromskloss (talk) 09:52, 13 May 2008 (UTC)

Silly me. A table like this should of course be computer generated. I've done that now with this piece of C code:
#include <stdlib.h>
#include <stdio.h>

int main(){
  double celsius, fahrenheit, kelvin, rankine, delisle, newton, reaumur, romer;

  printf("{| class=\"wikitable\" style=\"text-align:center\"\n! Celsius !! Fahrenheit !! Kelvin !! Rankine !! Delisle !! Newton !! Réaumur !! Rømer\n");

  for(celsius = 300; celsius >= -260; celsius -= 10){
    fahrenheit = celsius * 9/5 + 32;
    kelvin = celsius + 273.15;
    rankine = kelvin * 9/5;
    delisle = (100 - celsius) * 3/2;
    newton = celsius * 33/100;
    reaumur = celsius * 4/5;
    romer = celsius * 21/40 + 7.5;
    printf("|-\n| %.0f || %.0f || %.2f || %.2f || %.0f || %.1f || %.0f || %.2f \n", celsius, fahrenheit, kelvin, rankine, delisle, newton, reaumur, romer);
  }

  printf("|-\n| -273.15 || -459.67 || 0 || 0 || 559.725 || -90.1395 || -218.52 || -135.90375\n|}\n");
  exit(0);
}
—Bromskloss (talk) 12:31, 2 June 2008 (UTC)