> The freezing and boiling points of water are also not particularly pragmatic points of reference.
I must strongly disagree.
The freezing point of water is an incredibly important and pragmatic point of reference for hundreds of millions of people around the world, who live in places where water can freeze (or thaw) on its own outdoors. Not just for transportation, but also its affect on biology in agriculture.
While the boiling point is (thankfully) not important for weather-reports... Cooking! What would you do if I said to "simmer" something? You aren't supposed to go high enough to reach the obvious boiling point, so how are you supposed to know when you're close enough if you can't remember the magic number?
I'll concede that freezing is very important to a lot of people, but at the same time, I don't think it's particularly onerous to remember that the freezing point is 32 degrees.
As far as boiling and cooking, I would argue that there is no magic number anyways, since boiling point is variable by elevation. At 7500 feet / ~2250 meters, water boils at 198°F.
> As far as boiling and cooking, I would argue that there is no magic number anyways, since boiling point is variable by elevation. At 7500 feet / ~2250 meters, water boils at 198°F.
That's an excellent point, let's examine the relationship between altitude and boiling point, in both American units and everywhere-else-in-the-world units [0]:
5000 feet -> 202.97 F
7500 feet -> 198.33
10000 feet -> 193.6 F
Compared to:
1000 meters -> 96.73 C
2000 meters -> 93.38 C
3000 meters -> 89.95 C
In both cases, the boiling points at altitude are magic numbers. The difference is that with Celsius, you can interpret degrees as "percentage of the way from freezing to boiling". Going from 100 C at 0 meters to 90 C at 3000 meters is immediately meaningful as a 10% decrease. With degrees Fahrenheit, that same 10% drop in boiling temperature that happens at around 3000 meters / 10,000 feet is 212 F to 194 F.
If going from 100 °C to 90 °C was a 10% decrease, then going from 0 °C to 1 °C would be an ∞% increase. Metric units are superior to imperial for many reasons, but this isn’t one of them.
I must strongly disagree.
The freezing point of water is an incredibly important and pragmatic point of reference for hundreds of millions of people around the world, who live in places where water can freeze (or thaw) on its own outdoors. Not just for transportation, but also its affect on biology in agriculture.
While the boiling point is (thankfully) not important for weather-reports... Cooking! What would you do if I said to "simmer" something? You aren't supposed to go high enough to reach the obvious boiling point, so how are you supposed to know when you're close enough if you can't remember the magic number?