Above 0C you have liquid water, below 0C you have ice
I find this considerably more useful than the Fahrenheit equivalent.
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Imo the best system would've been Celsius with double the precision, e.g. water freezing still at 0ºC but water boiling at 200ºC.
That way you have the "human livable" range kinda between 0-100, which feels very intuitive. Anything above 100ºC becomes effectively unlivable. It also means that it is much easier to distinguish between certain "zones". e.g. saying "70s" or "80s" is easier and more clear than with celsius where you typically are staying within a sliding 10º range from day-to-day.
I agree this is an improvement, but you'd still have a bunch of negative number days in the populated northern and southern hemispheres, which Farenheit further improves upon.
Yes that is marginally better in Farenheit, but centering on the freezing point of water seems more useful overall. Then you'd also end up with the coldest spots on earth never being less than -200C and the hottest spots never being more than 200C which is nice symmetry.
> but centering on the freezing point of water seems more useful overall
But why? Knowing the freezing point of water (at sea level, mind you) is only rarely useful to me in daily life. I think the eutectic point of salt and water (that is, the lowest point at which it's possible to cause ice on the roads to melt by adding salt to them) is marginally more useful; this happens to be about -6F or about -21 C. Perhaps it's a bit more important for farmers who need to know whether their crops will freeze overnight, but as a lifelong city/suburbs dweller who knows next to nothing about agriculture I couldn't really say. At any rate, most people are not farmers.
I'm asking this somewhat rhetorically: I don't really care about Celsius vs. Fahrenheit. The pros and cons between the two are so vastly outweighed by the utility of having a global standard that I really wish the US would switch. I'm just pointing out that I don't think that one particular physical property of one particular substance makes for a very strong argument either way.
I think water freezing without salt is much more common than freezing with it. For example knowing the freezing point of water is useful for setting your fridge/freezer temperature.
Also: "below 0C my pipes might burst"
Or: "below 0C my plants might die"
Or: "below 0C the pond will start to freeze over"
This is exactly the system I would have designed!
in the temperate places most people live, the temperatures rarely drop below 0°F and rarely exceed 100°F and humans can sense a change of about 1°F so setting a thermostat in F is a simpler matter.
the 60's are warm in the sun and cool in the shade or breeze, the 70's are warm, the 80's are hot and the 90's are really hot, and over a hundred you're looking at death. The 50's you need a jacket, the 40's you need more jacket, the 30's are downright cold and you need an overcoat, and the 20's are frigid.
Celsius has approximately none of those properties. Celsius the 20's encompasses a vast change in comfort level.
As a celsius-user: you dont need more precision to judge how a temperature feels. The ranges you mention for Farenheit exist for Celsius as well. And if you need more precision you can use fractional numbers but I have rarely seen more precision in household thermometers than just rounding to 0.5 or the next whole number. I assure you that it is a completely usable scale.
To expand on your point: a difference of 0.5 degrees Celsius is almost exactly a difference of 1 degree Fahrenheit (really 0.9). So, indeed, a thermostat that can be set to half-degrees Celsius is roughly equally useful as one that can be set to full degrees Fahrenheit.