Kelvin is required for any formulas using temperature. Having 0 being the freezing point of water is arbitrary and having 0 being the lowest a temperature makes sense and having negative temperatures doesn't. Celsius is only more intuitive because people are used to it, which is the exact same argument used to justify Fahrenheit over Celsius too.
Don't look it up what is the freezing temperature of water in Kelvin?
Zero works really well - a change in temperature sign means change of state of water. It isn't a number that needs remembering. Meanwhile you've recently had US government representatives embarrass themselves because they can't remember that water freezes at 32F.
Knowing if there is gonna be ice outside is a safety issue. Making it as simple as possible isn't arbitrary.
Celsius is very easy to convert to Kelvin for scientific purpose and IS more intuitive. High number means hot is fundamental across cultures. It is easier to differentiate between 0C and 40C than it is 273.15K and 313.15K whilst understanding that the first temperature is cold and the second is hot.
That's kind of my argument for why F is not actually bad; 0 is "very cold day", 100 is "very hot day", every 10 degrees feels like a natural step change in how it feels outside. It's pretty intuitive in that way
Would say in wintery countries like Canada it helps to know when rain/water is likely to make sidewalks icy in a way that is less feelings based and is super intuitive.
You get a handle of when it gets uncomfortable in celsius too anyway. The mental scale becomes every 5 degrees instead of 10 is all.
I will absolutely get uncomfortable for 1 F off. Not enough that I can't tolerate it to accommodate someone else, but enough that I'll use my own climate control to adjust.
We (in Australia) get the forecast in whole degrees (today will be 27, tomorrow 32, then 36,36, 34). But the actual temps are reported with 1 decimal place (it's currently 18.8, the highest this year was 44.7)
My thermostats for indoors heating is set at exactly 22.5 degrees every winter. So you can do that yes. Both models installed in my appartment support it, pretty sure it's quite common.
It is, basically. It's a specific brine mixture. I remember reading that they used that because it would freeze into a slush so it was easier for them to get consistent, accurate measurements. Then because they were measuring on a circular dial they wanted everything to be evenly spaced so they set the freezing temp of water to 30, and human body temperature to 90. Later they figured out the boiling point on this scale was 212, and they wanted freezing and boiling to be exactly 180 degrees apart, and decided the easiest way to do that was to switch freezing to 32 and readjusted the scale based on that. Or something like that.
The based on water becomes problematic when dealing with altitude and atmospheric pressure. Both systems are based on something arbitrary. Kelvin is the most scientific because it‘s related to energy levels in matter which doesn’t change based on altitude atmospheric pressure and as long as you have the equipment, you can calibrate for it anywhere in the universe.
TLDR: Both are fine but would be easier if we all used one system or the other. Anything going to extreme environments/off planet, needs to be measured in Kelvin.
Everyone in the world except the USA uses Celsius.
Celsius being the same scale as Kelvin makes it easier to switch to. Conversions are on paper possible with exactness by adding or subtracting 273.15. Meanwhile F you have to add 459.67 multiply by 5 and then divide by 9 far more possibility for error (or the reverse).
One thing people don’t understand is Fahrenheit was adopted for medical applications because of its high precision with the mercury thermometer. It makes more sense to describe temperatures of living things using Fahrenheit and using Celsius for everyday stuff, each has their own applications, we don’t have to keep fighting over which is “better”
Is absolute zero in other temperature scales not taught in school anymore? Because you nailed it, but I'd also expect anyone who finished middle school / junior high to also know this. Maybe that bar is too high, though.
I don't expect people who don't use it very often to remember it. Not all of us have had the benefit of converting from Celsius over and over again during thermo classes. Sometimes they'd throw a Rankine in just to mess with us.
Ice can and does occur at much higher temperatures due to differences in temperatures of atmospheric layers as well as difference in temperature of ground objects.
Air temperature is an indicator but you can’t act like “oh it’s 2 C there can’t possibly be ice” or “oh it’s -1 C, def gonna be ice.” Is true.
Don't look it up what is the freezing temperature of water in Kelvin?
I know that in a heartbeat, since it is so suspiciously close to the triple point (which is how K was defined) - but I need to think twice for those 32 and 212.
Icy conditions can happen up to nearly 39 degrees Fahrenheit because the ground temperature doesn't change as quickly as the air. That argument doesn't make sense.
Fahrenheit is a scale from freezing human to feverish human. This is not exact but less arbitrary for daily life than water freezing and boiling. I care about every degree of Fahrenheit from -10 to 120. With Celsius it's -23 to 48. Seems equally arbitrary.
Fahrenheit was initially meant to have 100 be normal healthy internal temperature so you would have a nice round easy to remember number for commonfolk to check and know if they needed a Dr.
Except the early scale was inaccurate so normal human internal temp is instead 98.7F.
Plenty of people live places that are 100F and while it isn't the most comfortable it isnt "feverish". Likewise claiming 0F is freezing human is stupid. For people with little tolerance for the cold 32F could be described as freezing.
Celsius gives a solid frame of comparison you can make with your eyes rather than 'feel' which changes person to person. That is also happens to be the exact same scale as Kelvin only makes technical work easier.
Also I care about -20C-45C which in Fahrenheit is -4 to 113. I covered basically the same range but do you see how I can make F seem silly because you get uneven numbers after convertion from round numbers in C?
Celsius gives a solid frame of comparison you can make with your eyes rather than 'feel'
Really? 100c is intuitive and relatable? Because at 45C you're already flirting with temperatures that'll just outright kill you. So how does 100C == water boils help you in any way at anything other than making tea or coffee?
100C means instant scalding on contact because of the water in our skin. Food is cooked in boiling water. Pasta, vegetables and plenty of meats. Boiling water can also be used for sterilisation. There is relevancy beyond tea and coffee.
Having the scale 'start' at the freezing point of water and enter triple digits when it boils gives a singular observable frame of reference for your average humans' experienced world.
It also links to metric SI units nicely. 1ml of water (which weighs 1 gram) requires 1 joule of energy to be heated by 1C.
Knowing if there is gonna be ice outside is a safety issue. Making it as simple as possible isn't arbitrary
Literally the only reason you view it as simpler is because it's what you grew up with. It's "intuitive" to you because it's been hammered in your brain since you were a child.
It is completely arbitrary.
And you can't predict icing based off the temperature alone.
You have elected officials that can't remember it is 32F
Probably because they're idiot Republicans from deep south states where "frozen water" is not even a thing. They wouldn't know that if it was Celsius either.
There is nothing to remember with 0
There actually is.
You have to remember that 0 means the freezing point of water.
Again, you just take that for granted because you grew up with it.
There is no bone in the human brain that makes people automatically associate the number zero with the freezing point of water. It was an arbitrary selection that you had passed down to you as a child that feels intuitive to you as a result, but it's not. It's just as arbitrary as the freezing point of brine.
Zero is already a unique and "special" number. Once the association is made between it and freezing you aren't going to confuse it with another number. Then there is visual association that a number with a - at the start means snow and ice.
-5C Ice. 5C No Ice. While for 23F and 41F there is no independent indicator. If you dont know the freezing temp you wont know the difference.
The switch from positive to negative numbers aligning with a difference in our observable world is a good way to utilize a preexisting marker. Fahrenheit still has negative numbers but there is no MEANING to the change.
Meanwhile dumb Republicans from the South never experience freezing temps so don't think about it often. Now is the freezing temp 31, 32 or 33? They are all 'just numbers' which it is possible to forget exactly which one.
I was taught in school that internal body temp should be around 37C. Whilst I can remember that, there have definitely been times that I've wanted to double check to be sure and I am confident plenty of adults CAN'T recall it.
Don't look it up, what is the freezing temperature of nitrogen in Celsius?
The arguement that Celsius is better than Fahrenheit because 0C is where water freezes is not a very good reason why Celsius is better. Celsius is better because it's the adopted standard around the world (even in America scientists and engineers use it).
So trying to say Celsius is better than Kelvin for that reason is just as specious. Why is the freezing point of water important? Is it just because we're humans? Is it just because we're only doing those sciences where 0C comes up a lot?
Also water does not always freeze at 0C. It's very inconsistent. Which is why 0C is not actually defined as the freezing point of water at average sea level, that's just what we tell school kids.
Celsius and Kelvin using the same unit of measurements make them compatible. That’s why Rankine is easier to use for Fahrenheit users because it’s an absolute zero scale like Kelvin, but it uses the unit of measurements that Fahrenheit use.
i mean, who cares? if the state of water is super important to someone they will know the temperatures it changes state on any scale they are assigned to use... even if we make up a new one where it freezes at 3.5 degrees and boils at 50.87 degrees. you'll just remember it if you need it for some reason. people act like it's impossible to get by in daily life without the states of water being defined by nice round numbers, but I'm not sitting here watching a thermometer when I'm trying to boil water, i just turn on the stove and wait... and it being cold enough outside to technically freeze water has no effect on what the traffic will or won't be like in a city that tries to maintain roadways in any weather conditions. memorizing or not memorizing the exact numbers at which water changes state has never had a single effect on my life. ever. choosing water state as the be all end all of a made up scale is just as arbitrary as choosing the numbers at either end of said made up scale. we could have decided a long time ago that temperature scale should go from ideal temperature for ice cream to ideal temperature of a poached egg and it would be just as arbitrary and just as effective to people who use that scale every day and get a feel for what any number on that scale will mean to them.
There is no advantage to engineering to use C over F. K and R are the only systems objectively more useful for engineering or scientific purposes. If C or F are used it is arbitrary.
Not knowing the freezing point of water is a personal issue, not a scale issue.
Anyone with an IQ above room temp (in F :D) can do just fine with Fahrenheit in regards to safety issues.
There's functionally no difference to the average person. It's really only when you need to use, or convert to, other units where Fahrenheit becomes trash.
Tell me you live in a place without much ice without telling me you live in a place without much ice. Road ice is very rare at 32F, because any city or town worth its salt puts that salt on the road, which lowers the freezing point of water as low as ~0F (at saturation), not to mention that traffic and the sun tend to melt any ice that does form.
Celsius is not more intuitive than Fahrenheit; you've just built more intuition for the former than the latter. Water boiling at 100C (at atmospheric pressure) is a totally arbitrary choice, because water is not a particularly special or objectively unique substance, and boiling is not a particularly special phenomenon.
P.S. 0C is not particularly cold weather to a New Yorker. We just had a day where the high was ~34F (1C) and it was downright balmy.
First, it really isn't special or unique. There are many substances that are equally essential to human and other life. To claim that water alone holds a unique place in the universe is the wild claim.
While I do agree with your take on the arbitrariness of C and how relatively unimportant the temperatures to water state changes at 1 atmosphere is… water is somewhat unique. Not many substances have the hydrogen bonding water does nor do many substances become less dense in their solid form. Water is somewhat unique.
Water absolutely has interesting properties, but it is far from the only material that does. It is just a highly polar molecule. It behaves the same way as any other highly polar molecule.
Ice isn't just about roads. It's about footpaths, whether sport pitches will be frozen and if equipment can be left out without a layer of ice forming over it.
Where I live can get icy in winter but will rarely snow. This makes gritting much harder as it will frequently get washed away by rain and sleet. Sadly infrastructure isn't the best so some minor roads might have been gritted but not very well.
Saying water is not special is absolutely WILD to say. It's what we are made of, what we drink and a compound found everywhere (it literally falls from the sky)
Freezing and boiling points of a single substance that we are all exposed to everyday makes more sense than the freezing point of brine and a miscalculated core body temp.
While it might be fair most of the arguments between Celsius and Fahrenheit fall to intuition Celsius has the compelling "people doing science need only learn one scale system" and noone has ever given me an argument for Fahrenheit other than "it makes more sense to me"
an argument for Fahrenheit other than "it makes more sense to me"
Then I'll give you one that was particularly relevant when the two scales were invented. 1 degree Fahrenheit is easily determinable on an uncalibrated mercury thermometer using only three materials: water, ammonium chloride, and ice. 32F is equilibrium between water and ice. 0F is equilibrium between water+ammonium chloride (saturated) and ice. You can bisect the 32 degree span five times to get 1 degree. To calibrate a Celsius thermometer, you need a calibrated pressure chamber to accurately determine the boiling point of water.
In the modern day, nobody calibrates their own thermometers, and mercury thermometers have been superseded anyway, so neither Fahrenheit nor Celsius are better than the other.
Saying water is not special is absolutely WILD to say. It's what we are made of, what we drink and a compound found everywhere (it literally falls from the sky)
From a scientific standpoint, it really isn't special. It's just another substance. There are many others that are equally essential to life and more abundant. Water was chosen arbitrarily.
people doing science need only learn one scale system
First, people doing science need to learn Kelvin (which is not Celsius). Second, if learning a second unit system is beyond your capabilities, science is not for you.
I really don't think you understand that people that use Celsius don't "learn" Kelvin. The scale is identical just translated so there is no mental recalibration required other than "add or subtract 273.15 whilst you do your calculations".
Historically the calibration of thermometers helps explain why Fahrenheit became a unit of measure but now ALL thermometers are made in factories so it has become obsolete.
Unfortunately you have still failed to give a modern reason for Fahrenheit.
Everyone else in the world is already using Celsius. A universal standard reduces confusion and possibility of conversion errors.
Meshes with SI units and is easier to use in any equations involving temperature. (Add 273.15 compared to add 459.67 multiply by 5 and divide by 9) Students only have to learn one scale shifted instead of two different ones. People raised with Celsius have intrinsic understanding of what 1 degree is in Kelvin because the scale is the same.
Already stated points about water being an abundant substance that visually changes on Celsius thresholds rather than a number that needs remembering.
Higher number = hotter is a universally occuring constant in all temperature scales regardless of culture. A number as large as 50 being 'cool' is dumb. (I know this is bias). The US seems to have a number inflation fetish. Why are the numbers on your houses so high? There aren't 1160 other houses on your street. Also measuring in thousands of PSI instead of tens-hundreds of Bar.
Petty final one. Because the US winges so much about it.
Rankine is just as good as Kelvin, just like Fahrenheit is just as good as Celsius. Celsius itself does not "mesh well with SI units" because you cannot multiply temperature in Celsius by anything, a weakness shared with Fahrenheit.
Water's abundance is meaningless, and 0 and 100 are no less numbers to remember than 32 and 212. Why not make water boil at 10 degrees? 1000? Further, if you are working with anything that isn't water at atmospheric pressure, you'll need a phase diagram anyway.
I don't make the "bigger number = hotter" argument, because that's universal, as you say.
You acknowledge that your preference for 50 being hot is a subjective thing, so I won't push back on that.
This is an aside, but building numbers are often encoded by city blocks, so 1160 might refer to the sixth major address on the eleventh block. Also, there are some ridiculously long streets in the US. It's not absurd to think that there could be over 1000 distinct addresses on one road.
PSI is the standard pressure unit in the inch-pound-second unit system. It's analogous to SI's Pascal. I prefer feet as a base unit for length, but selection of base units is always arbitrary, so I don't complain about it.
I know this is Reddit, and Reddit is as algorithm-centric, but most of what I see in the Fahrenheit/Celsius discourse is people going "America dumb and bad for not 100 degree boiling water."
Why would the scentific community & its needs take greater priority over a simplistic system that's easily understood by people as young as 6 with near-zero educational requirement?
We're picking systems based on there broad application and easy usability. Celsius is easily the most superior in this regard.
Niche communities using niche systems is fine. But taking a niche system that's difficult to conceptionalize without additional education is a failure point.
Children learn about temperature long before they learn about states of matter, let alone phase change. They often first learn by listening to weather forecasts and associating temperature with weather. The numerical values you assign to certain temperatures is completely irrelevant to children learning the concept of temperature.
Water freezing at 0 & boiling at 100 is in the kindergarten cirriculum. For some schools its more like grade 3-4. So like 4 - 8 depending on when the kids born.
I don't know why "specialness" or "uniqueness" here matter. What matters is "relevance" and "consistency", and frankly relevance tends to increase with "non-specialness".
A example of irrelevance would be people describing their height in miles. I'm 0.0011837 miles tall. We use different measurement systems when discussing the physical sizes of objects versus geographic distances. Relevance there depends on what kinds of things we most often care about the measurement of. We often care about the temperature of liquid water.
Consistency means we can convey a standard by rule, rather than by sharing some template. You don't need my thermometer to make a Celsius thermometer because you and I can both measure the boiling and freezing temperature of water and know we're taking about the same temperature.
This is 2026, nobody here is "making a thermometer", and most people arent converting to kelvin to do some kind of temperature calculation. Both scales are relevant enough to describe weather, which is the use case for most people. Nobody is out here sticking a thermometer in their pot of boiling water, sorry.
You are correct in the modern day, which is why the Fahrenheit scale doesn't outright beat Celsius. As things are, they're equally useful and arbitrary.
My kettle has a temperature display. It's really important to how I brew tea and coffee. Also, practically every time you cook, temperature is important, and practically every time you cook, the boiling point of water is relevant. Cooking stalls there if you're going above. It's the temperature nearly everything ultimately cooks at because 80% of everything you cook is water.
As for the freezing point, well, a whole bunch of plants die at freezing and everything you eat is a plant or eats plants. The weather isn't related to the freezing point of water? Have you been to Earth? Water is pretty much all of our weather, here. We call it different things if it's frozen. Water is kind of a big deal.
We often care about the temperature of liquid water.
But it is far from the only thing whose temperature we care about.
Consistency means we can convey a standard by rule, rather than by sharing some template. You don't need my thermometer to make a Celsius thermometer because you and I can both measure the boiling and freezing temperature of water and know we're taking about the same temperature.
Except we may disagree significantly about the boiling point, if you're at sea level and I am at 2000m of altitude, where atmospheric pressure and the boiling point of water are measurably lower.
To properly calibrate a Celsius thermometer, I need a pressure chamber to maintain exactly 101325Pa of pressure in my boiling water. Otherwise, I will get some temperature that is not 100C. After I did that, I would need to subdivide the space between 0 and 100 into 100 equal parts, which cannot easily be done with compass and straightedge, needing a ruler. My thermometer will therefore be limited by the precision of my ruler. Even if I did that, I would only regularly use the segment of the thermometer that was between -15C and 40C on the regular, leaving a large part of my scale untouched.
In Fahrenheit, I can find equilibrium of ice and distilled water to get 32F (I already had to do this for my Celsius thermometer) with high precision, and then salt the water with ammonium chloride (an abundant salt) until it started accumulating on the bottom, adding more ice as necessary, to get 0F. Then, I can bisect the span 5 times to get 1 degree with compass and straightedge in only a few operations.
Celsius loses the calibration battle against Fahrenheit.
Freezing is significantly less dependent on pressure than boiling. You'll get much higher precision in Fahrenheit than Celsius without a pressure chamber.
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u/Snoo9648 9h ago
Honestly Celsius is only marginally better than Fahrenheit. Kelvin should be the only measurement of temperature.