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Comment by acangiano | Hacker News Reader

Much better visual evidence: http://signword.files.wordpress.com/2012/02/423399_101506340...

Pretty weak argument for Celsius. Why should people care that the boiling and freezing points are simple? That is almost irrelevant for the most common uses of temperature reporting. People care about the ambient outside temperature (which Fahrenheit seems optimized for), not the effect it has on the state of one particular compound.

Fahrenheit is not really optimized for that either. It's basically optimized for "still positive in the coldest days in Denamrk some 200 years ago, and less than 100 in the warmest days". (Seriously)

If you live in e.g. San Diego, it goes from ~60 to ~90. If you live in NYC, it goes from ~25 to ~100. That's not more optimized than Celsius, which goes from ~15 to ~30 and ~-4 to ~35 respectively.

However, when in NYC, you know that negative celsius means black-ice out in the street; zero celsius mostly means snow, and positive celsius means non of the above.

Also, you know that 1kcal that you get from food (or Con Edison) will heat one liter of water by one degree celsius (and a quart is a good approximation for a liter, if you're still in NYC ...)

Here is the thing: Created for still positive for the coldest days in Denmark and under 100 for the warmest is optimizing for ambient outdoor temperature. And much more human readable than heating one liter of water etc. I am not saying it is perfect, but I don't see why it shouldn't continue to be used as it is currently: F for weather reports and such while using C/K for more scientific pursuits.

Yet, it's quite handy that Celsius is based on the freezing temperature of water in winter. You always now when you'll have ice on the streets, cars, etc. :)

Remembering that 32 is freezing is not taxing and gives you the same amount of information (i.e., almost none because temperature alone is a poor predictor of weather).

The freezing temperature matters far less than you think. There is "latent heat" that must be added to ice to make it melt and removed from water to make it freeze.

Just the other week we had a wintry mix of precipitation at a nice and balmy 0.5 C which resulted in accumulated snow and ice, despite never being below freezing at ground level. It even warmed up through the day slightly to 1.7 C or so but the ice and snow never completely melted as there wasn't enough heat to overcome the latent heat of vaporization needed.

And as mentioned elsewhere, it's not exactly difficult to remember "32 F is freezing", even the most dense Americans have figured that out so it's another metric solution to a problem that doesn't actually exist in America.

Water's freezing point is easily the single most important temperature there is when it comes to (outdoor) temperature. Essentially, it tells you whether travelling is a deadly hazard or not. It tells you whether to expect snow or rain (which require quite different types of clothes). At least for those of us living in places with snow (as Celsius did), there's no more sensible thing to base the temperature scale on.

When it comes to boiling point, yeah I can give you that it's perhaps not as obviously the right thing. But it's the logical other end of the scale, and most of us do care about it several times daily, when cooking.

Even when I'm cooking I never care about the temperature of my water in Celsius, especially since 1) its exact boiling point will vary depending on the air pressure of my present location, and 2) impurities in my tap water (as well as my standard metric pinch of salt) will alter the boiling point of the solution.

So while I do really adore the metric system, the gp's argument still stands: Fahrenheit just so happens to coincidentally peg 100 somewhere near "too damn hot" and 0 to "too damn cold", and I don't see why civilians would benefit from mandating that weather reports be specified in Celsius (and I'd honestly rather prefer Kelvin than Celsius).

People care for various temperatures:

- weather (Celcius has the advantage that just from the temperature you know if there will be snow and ice/will snow melt, or no) And you won't know the difference of 1 C anyway, so no point in having so small degrees.

- temperature of human body (are you sick or not - it's 36.6 C for healthy human, 40 C for dangerous temperature) - here Fahrenheit has slight advantage, because human body temperatures are near 100 F, IIUC.

- temperature for cooking (water boils in 100 C, you make tea with 80 C, most cakes bake at 220 C, etc) I think Fahrenheit is worse there.

- temperature for science/engineering (Kelvin rules here, but Celcius is just Kelvin - 273.15, so conversion is much easier than Fahrenheit, differences are same in K and C).

There is a point in having small degrees, in that small fluctuations in the weather are more noticeable. I can say that the weather will be in the 60s today, and people will know what I mean, but saying it will be in the 20s today (in celcius) offers a much larger range of weathers to be had.

Also, you can tell just as easily if something melts using Fahrenheit, you check whether it's above or below 32. Sure, it might seem a little arbitrary, but it's just as arbitrary as "36.6 C is healthy" or "cakes bake at 220", which people seem to remember just fine.

This is the reason why nobody ever would say "in the 20s" when giving a temperature in celsius. Instead people either say "about 25" or give a range ("20 to 25"). The size of units change how people express themselves.

Yeah, never understood the "problem" with Fahrenheit. When I ask people to tell me why Celsius is better, many will tell me because its "decimal", and then I point out to them it is no more decimal than Fahrenheit, there are no "kilodegrees". They will then point out the water freezing/boiling, as if they regularly have to set that temperature to accomplish that (you don't, you just put water in the freezer or a kettle on the stove). Celcius is annoying from a practical perspective because you have less degrees to deal with in every day temperatures, and in Fahrenheit 0 is "cold" and 100 is "hot" (vs like -20 to 40).

In Celsius, a negative temperature means snow instead of rain, or icy streets instead of wet. Whether the ambient temperature is below freezing is pretty useful knowledge, and more clearly expressed in Celsius.

As for the difference between 16 and 17 degrees, the only people who give a shit are people who know how to use decimals for their measuring purposes. In everday use, the finer gradation of the Fahrenheit scale are irrelevant.

The way to know whether it is going to snow or rain is to check the weather report, mainly because more factors go into that than just the temperature (for example, amount of moisture in the air, cold/warm fronts, etc -- which can lead to anything from snow, hail, sleet, or freezing rain). I imagine you are generally getting your temperature from a weather report anyways (unless you are looking at some sort of personal thermometer before heading out the door?) so the information will be presented to you there alongside it, not requiring you to do any mental calculus to figure this out yourself.

It's not about whether it will snow or rain, it's about whether precipitation will be frozen or not, and all you need to know that, for precautionary reasons, is the temperature. It's not a large advantage of Celsius, but it is pervasive.

ETA: To be clear, I'm Canadian, and grew up with Celsius. Whether the temp was positive or negative was the second thing worth knowing after the actual number. It was a very practically useful bit of knowledge in everyday life, easily given and easily remembered.

It's "better" because it's just an offset Kelvin scale. So when you're doing delta calculations, there's no difference. And really, most temperature calculations are relative.

Fahrenheit is just an offset Rankine scale.

Does anyone actually use the Rankine scale?

Please be aware that Celsius is not a SI unit, Kelvin is used in stead as the standard temperature unit. The only reason why many people use Celsius is because it makes sense in their daily lives. The melting and boiling point of water are both important in cooking and the freezing point is also important for the weather. Therefore it makes a lot of practical sense to use Celsius and people have stuck to it even though it is not an SI unit.

Kelvin should be the logical choice for temperature: http://en.wikipedia.org/wiki/Kelvin

... or not: http://www.nature.com/news/quantum-gas-goes-below-absolute-z...

It's not weak at all. I don't know about you, but I'm surrounded by decimal measure systems and I find other old/weird legacy systems brain-damaging (please don't bother mentioning exceptions, I'm aware of their existence even in the metric system territory). I prefer the centigrade over something else anytime. The fact that Celsius have chosen 0 and 100 for for freezing and respective for boiling normal water in normal atmospheric pressure outweighs any other possible reference in regard to its relevance to a human.

I'll sum up for you: normal water, normal pressure, normal reference-peeking, and normal and logical 100-sized interval reference.

EDIT: fixed a typo

DD/MM/YYYY doesn't make any sense either unless you write numbers with the most significant digit on the right. Only YYYY/MM/DD actually makes sense (which is why lexicographic sorting automatically works when you use it).

mm/dd/yy makes sense to those who use it, given our cultural adjustment.

My father's argument for imperial is how easy it is to divide measurements. In woodworking, especially. 10 is divisible by 2 and 5. Powers of two are more flexible for division.

That's why plywood in Europe is usually sold in sheets of 240 cms, i.e. 2.4 m, which seems easier to calculate with, in particular when adding lengths.

Put a tape measure along a sheet of plywood and prepare to be surprised. At least then you'll know why you always had trouble fitting them :)

Ease of use with imperial? I say no way. Trying to add 1/16 and 1/5 is somewhat harder than mm addition.

That's why you don't cut to 1/5...

I suppose it's all numbers in the end.... Mankind has found a way in the rest of the world to make metric work!

Does your father change units each time he needs to divide something?

Only between feet and inches, but usually, he's working solely in inches (and fractions of an inch) for his projects.

I didn't get how using inches is easier here. Can't you also do all these calculations, with the same ease, using centimeters?

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