First of all, the °C is not the metric SI unit for temperature. K (Kelvin) is.
Second, even with Kelvin, nearly all temperatures that matter for normal human issues happen to be below 4000K, usually way below that mark. And with most of those temperatures, about all digits usually count. A core body temperature of 310K or 313K makes a BIG difference for the person involved.
Celsius is the SI unit of temperature. Kelvin is the SI unit of thermodynamic temperature. They’re both defined in SI.
You can say anything with confidence and people will believe it
https://en.m.wikipedia.org/wiki/International_System_of_Units
Kelvin is the base unit. Celsius is a derived unit, just like Watt or Newton. But they’re all SI.
I was agreeing with you, I was referring to OP saying it isn’t SI. But I think the downvotes are showing that wasn’t clear enough.
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I’ve seen mK used numerous times, but I haven’t seen, like MK for internal temperatures of stars or things. I imagine because those are more “for fun” numbers while the precise temperatures in a low temperature physics lab are four technical purposes.
Isn’t Kelvin just Celsius+273.15?
Celsius uses an arbitrary reference point (freezing point of water). Kelvin uses the same sized units, but is referenced from absolute zero. While this seems just as arbitrary, it actually makes some scientific calculations a lot easier.
Basically, scientists have been working to slot the various base units together in a neat and orderly manner. Kelvin fits this far better than Celsius, and so became the baseline SI unit.
Yep! Celsius does make sense for our everyday life
I fully agree with that. It’s also quite easy to shift between the 2. I just had the difference drilled into me way too much, at university.
Fahrenheit is better for human-survivable temps.
Fahrenheit:
- 0° - Really cold
- 50° - So-so
- 100° - Really hot
Celsius:
- 0° - Cold
- 50° - Extremely hot
- 100° - Dead
Kelvin:
- 0° - Dead
- 50° - Dead
- 100° - Dead
Some people seem to have this misconception that “0F cold 100F hot” is somehow an innate or intuitive concept for everyone. It’s not, brother, you just happen to be used to it. I have absolutely no idea if I should wear a coat with 62F or not, or for any other F temperature for that matter.
At least 0C and 100C have very practical references that anyone can recognise, but what the hell even is 0F and 100F?
Also, not sure why you’re trying to shoehorn 0-100F to 0-100C.
When talking about weather, it’s going to be in a range like 0C (cold) / 20C (nice) / 40C (hot), which is equally arbitrary but probably more useful than 0F/50F/100F anyway depending on where you live: my neck of the woods goes to 0C in a harsh winter, and to 40C in the peak of summer.
And do you use F for stuff like cooking? What purpose is 0F or 100F there?
How about stuff like chemistry or physics? I remember formulas in C or K, occasionally having to add 273.5. Is F used, or you just use K/C and convert at the start?
Because physics uses Kelvin for high temperatures, and electron volts for really high temperatures.
And Kelvin for really low temperatures, too. mK used a lot more than MK in many a physics lab…
Because kilodegrees sounds funny. But megadegrees really sounds volcano lair evil.
Megadegrees sounds like something graduates from Trump University got for finishing a retreat. They are the highest quality degrees - so good they deserve to have their own name!
Going back to temperature though, it would be odd-sounding to say the Sun can get as hot as 15 megadegrees at it’s core.
Give it a few kilomonths
Would just be confusing. Temperatures above a few hundred degrees have no place in most people’s daily lives, so that would be mostly for scientific notations, and scientists use Kelvin anyway for precision.
The use of kelvin over Celsius has nothing to do with precision. They’re the same thing, with different offsets.
Technically yes and no. Kevin is absolute temperature, since the offset is zero it measures the total temperature. Celsius is relative, since the offset places its zero at a conventionally useful place it measures deviation from that baseline. That’s why you have temperatures always in K and never °K, but always in °C and never just C. But yes, the sizes of the units are the same.
Kelvin and Celsius can both be used interchangeably and you can always get the same answer every time using either; they are equally as precise. So is fehrenheit for that matter, although the conversion would get even more complicated.
It’s just usually using the one with zero offset makes the math easier, which is why it tends to be the one used for scientific calculations.
When the measurement being used is ∆T, change in temperature, this is correct. Occasionally, like in the ideal gas law equation, the measurement is T, or absolute temperature, which requires zero offset. In these cases, Celsius will give the wrong answer.
As I said
It’s just usually using the one with zero offset makes the math easier
You can use Celsius in the ideal gas law. You just have to make sure to include the offset in your calculation. There is no loss of precision by using Celsius, and it isn’t wrong. It’s just the math is easier if you use kelvin, because as you point out (in this case) it’s the ratio of the absolute T that’s important, and a delta T is not enough.
By including the offset in the calculation, you have converted to kelvin.
Yes, as I said repeatedly, the math is easier which is the reason. If you didn’t include the offset in the calculations, you wouldn’t lose precision, you’d just be wrong.
I’m at a loss as to what you don’t understand.
Fahrenheit solves this
How exactly?
I usually do
46°C instead of 46° ???
You are doing it right.
It’s really when you get into the thousands though that SI prefixes generally start to be used, you don’t see deca or hecto used that often. It’s mainly because we’re usually happy keeping three digits of precision in general conversation (185 degrees C, 250 metres, etc). After that we get a bit sloppy and start rounding, and that’s where kilo comes in and we start talking about “1.25 kilometres” and such.
Add in the fact that people rarely need to describe temperatures higher than 1000 degrees C with any precision, (they’ll just round to hundreds/thousands/millions usually) and that’s why SI units feel weird with temperature.
Interestingly, I hear people use terms like millikelvin and microkelvin often enough, but never kilokelvin. In fact, there are some hilariously impractical ways to avoid large scientific notation for Kelvin. There’s T4, which is the temperature in kelvin divided by 10^4, and there’s electron volts, which is almost the same value, but preferred by different fields.
Guess there’s not much need. Most of the prefixes used are 1000 (kilo, mega, etc.) or 1/1000 (milli, micro, etc). The tens and hundreds are a bit odd to use and imo shouldn’t be used. So there’s no need to use prefixes until you’re into Star temperatures or really extreme experiments.
Where I think they could be used is for in between temps. 1 degree centigrade covers a wide range when it comes to precision cooking like sous vide. Would be nice to drop to a smaller unit, but since metric can only work in multiples of ten, going down a level becomes overly precise.
The result is that I tend to prefer Farenheit for cooking, especially for sous vide. Unless you’re doing molecular gastronomy shit, converting between units isn’t that useful; you don’t need to worry about how many Jules it’s going to take to boil a given volume of water.
Conversely, grams are way nicer for measuring most things in the kitchen.
Centicelsius has a nice ring to it.
centi- actually means 1/100th in the metric system
It would be centidegree.
370 Centigree
That’s ® worthy, fam.
Too close to centigrade, plus centi- actually means 1/100th in the metric system.
There’s nothing special about 3.7°C, but there nothing NOT special about it either. <.<
[Edited because of weird auto-formatting. Edit 2 added more pedantry. Edit 3+ is because I lost the plot and had to bring it back.]
Because the SI unit for temperature is the Kelvin, which has already been stated. It has also been mentioned that K and °C are the same but with different offsets. It has not been mentioned that °C is to K as Degrees Fahrenheit (°F) is to Rankine ( R). It would be similarly inappropriate to say “millidegrees Fahrenheit” or “kilofahrenheit”. I have no idea if mR or kR would be appropriate, though.
I would offer that there are two ways to look at SI (“metric”) prefixes, and these can be thought of similarly with the multipliers they represent: as a prefix to the unit, by definition; or as a suffix to the value. Let me illustrate with an example.
38,000 K could be expressed 38 kK, or “thirty-eight kiloKelvin”. It could also be spoken “thirty-eight thousand Kelvin” (or Kelvins, idfk). This isn’t normally important for the layperson, but suppose you have a temperature meter (and, literally, I do not mean “thermometer”) that has only 4 digits of resolution. 38.00 k (“38,00 k” for the Europeans?) would be how it reads out the value in question. This would be 38 kK, certainly, due to the position of the decimal.
Now suppose that temperature meter read out in °C. 38.00 k °C would, in fact, denote “thirty-eight thousand degrees Celsius” for the reasons mentioned above.
So, because Degrees Celsius is not an SI unit, in the technical sense…
Btw, I have been explicitly using upper case letters when spelling out the units. This is incorrect. The symbols for SI (International System of Units) units should be capitalized when they respect a person (K, A). The names of the units should be all lower case because you are not naming the person, but the unit named after them (kelvin after Lord Kelvin, and ampere after Andre-Marie Ampere).
Yeah, I know. I’m being pedantic. It’s literally my job. I really should be sleeping right now. Here’s a source: https://www.bipm.org/en/measurement-units/si-base-units
There’s no way someone would use something as logical as “Millifahrenheit”.
It’s be 143 Fahrenheit in a Blurgenfurl, 2 Blurgenfurl in a Whatjamagick and 19003 Whatjamagick in a Plenderboing.
prefix
You mean suffix? Usually the C or F (or K for that matter) are denoted last, not first.
Milli centi kilo
OP means prefixes, like 1000°C = 1 k°C
No, they mean like “kilocelsius” or “millicelsius”, which makes them prefixes
