# Fahrenheit vs Celsius

1. Oct 15, 2012

### SW VandeCarr

A meteorologist friend of mind told me a story about an American who owned a condominium overseas. The owner got an email from the caretaker saying the temperature in his condo was 32 degrees and for asked permission to turn on the air conditioning and set the thermostat to 28. The owner promptly replied:"ARE YOU CRAZY!? Turn on the heater and set the thermostat to 55 right now!" Angry at receiving such a rude reply, the caretaker dutifully complied, even to the extent of replacing the heater thermostat with one for an electric oven that could be set at 55 C (131 F).

It's not clear if the story is true or just part of meteorological lore, but my friend does think that the real choice is between Fahrenheit or Kelvin. He points out if a relative scale must be used, Fahrenheit is better because it's a finer scale (1C=1.8F). The fact that Celsius is scaled to the phase transitions of water is merely an aesthetic advantage in his view. Besides, there are no recognized named multiples or divisions of the Celsius/Kelvin degree. It's not really a metric unit.

So are Americans really right to hold out and not adopt the Celsius scale for weather reports, cooking and taking your body temperature?

Last edited: Oct 15, 2012
2. Oct 15, 2012

### AlephZero

Fahrenheit vs Kelvin?? Don't you mean Rankine and Kelvin? (They both have 0 at absolute zero). Or Fahrenheit and Celsius?

FWIW I've had fun and games with US propulsion engineers supplying us with temperatures in R, but not bothering to state the unit. And ignoring the "K" on data we sent to them, because they thought it was a typo.

3. Oct 15, 2012

### Staff: Mentor

The actual measurement of temperature is the same no matter what you use, so in terms of accuracy and precision it doesn't matter which unit you use.

4. Oct 15, 2012

### SW VandeCarr

My friend means Kelvin for scientific work and as I said, if you must use a relative scale for everyday uses, Fahrenheit has a finer scale. You get a more precise reading for the same number of characters. He doesn't want to replace Kelvin with Rankin. Kelvin is well established everywhere, but Celsius is not widely used by the general public in the US and my friend thinks nothing practical would be gained by switching to it.

EDIT: I think my friend wants to use Kelvin exclusively in meteorology, including weather reports, but if that can't be done, he believes it's better to stick with Fahrenheit.

Last edited: Oct 15, 2012
5. Oct 15, 2012

### Astronuc

Staff Emeritus
The Fahrenheit scale is also an arbitrary scale with the phase changes of water, the melting/freezing point and boiling point separated by 180°F/°R. It's just as arbitrary as 100°C/K.

I have to use both English/British and SI/MKS (and occasionally cgs) systems in my work, but I prefer metric.

6. Oct 15, 2012

### Staff: Mentor

That's just silly. Hasn't he heard of decimals?
Even if the first thing were true, which it isn't, it wouldn't be relevant to the second, which is also wrong.

http://en.wiktionary.org/wiki/millikelvin

7. Oct 15, 2012

### Staff: Mentor

Right: depends on the instrument.

8. Oct 15, 2012

### SW VandeCarr

OK. He's a research based meteorologist. I think his point is that in published weather reports the number of characters is fixed. If you say 1 C, it could be 1 F or 2 F because you don't have the option of using decimal fractions. This is quite common.

Last edited: Oct 15, 2012
9. Oct 15, 2012

### Staff: Mentor

Are weather models precise enough for that to matter? Or does the extra precision in the presentation provide a false sense of precision in the prediction?

Also, climate data is published by the government in a precision of .1C: http://www.nrel.gov/docs/fy08osti/43156.pdf

So perhaps it is just the day-to-day weather forecasts that are lower precision.

10. Oct 15, 2012

### Staff: Mentor

That was what I was thinking. If you are using the temperature in casual conversation and just using whole numbers then Fahrenheit would be more accurate. However I don't see much of a need for this accuracy in such circumstances.

11. Oct 15, 2012

### Mentalist

Fahrenheit sounds better.

12. Oct 15, 2012

### Staff: Mentor

I would rather use Kelvin.

13. Oct 15, 2012

### SHISHKABOB

I like Kelvin because it's got absolute zero right at zero.

14. Oct 15, 2012

### SW VandeCarr

Well my friend likes Kelvin too. An absolute scale is necessary if you're going to use temperature with other units and Kelvin is the SI unit for temperature. As I said, my friend wants only Kelvin for meteorology, but he realizes that it might be difficult for the general public to get used to hearing weather reports saying things like the high temperature for today will be 300 (K). I will say that that's never going to be mistaken for a Fahrenheit temperature in a weather report like Celsius might be (see post 1). His point is that if the US public is going to be re-educated to a new measure of temperature, it should be Kelvin, not Celsius. Otherwise, he says we might as well stick to Fahrenheit for things like weather reports, cooking and taking body temperatures.

I'm just asking for comments on this. Should the US remain practically the only country in the world that still uses Fahrenheit given Celsius arguably offers no inherent advantage but would conform to what the rest of the world is using?

Last edited: Oct 15, 2012
15. Oct 15, 2012

### Staff: Mentor

I say no, but I realize that the public would most likely be overwhelmingly negative in their reaction to such a change.

16. Oct 16, 2012

### SW VandeCarr

OK, but should we convert to Celsius or Kelvin? If it's Kelvin, the US would be ahead of the world instead of behind as it usually is in things like this.

17. Oct 16, 2012

### Staff: Mentor

I don't think there is a "right" answer to this.

18. Oct 16, 2012

### Jimmy

Recall seeing this on the forums fairly recently:

On the serious side, Kelvin doesn't seem to be a very practical scale for weather forcasts aimed at the public and conversion between Celsius and Kelvin is pretty simple. If America did officially switch to Kelvin, I'm pretty sure forecasts would still use Fahrenheit as well.

19. Oct 16, 2012

### PhysicsGente

I grew up using celsius so the choice is obvious ;).

20. Oct 16, 2012

### PhysicsGente

I grew up using celsius so the choice is obvious ;).