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Comment by davidhyde | Hacker News Reader

It’s “Scientific” American yet they quote negative 300 degrees Fahrenheit. Use kelvin for low temperatures or, if you have to, at least degrees Celsius. For the benefit of the reader -300 F is 89 kelvin or -184 Celsius which is about 10 degrees c above liquid nitrogen’s boiling point.

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> It’s “Scientific” American yet they quote negative 300 degrees Fahrenheit.

It's Scientific American, yes. I mean, sure, they could have used Rankine but...

The article is about human colonization, so Fahrenheit is more appropriate unit because it represents human compatible temperature ranges better than C or K.

Exactly. Very few people get this. Fahrenheit is better for communicating temperatures in daily life.

Plus we can be more precise in our language due to the expanded scale. e.g. We can say 62 degrees F, rather than 16.6667 degrees C.

> Exactly. Very few people get this. Fahrenheit is better for communicating temperatures in daily life.

Literally the entire rest of the world disagrees with you

I've never needed a less than 1 degree unit for describing temperature, except in scientific contexts, where using 2 decimal places is fine

I don't see why "100 ~= body temperature (with fever)" is a useful scale point. Or why 32F = freezing is useful in daily life

Normal body temperature was defined† in Celsius, at 37ºC; this explains the decimal when used in Fahrenheit (98.6F). So even that argument of convenience doesn't hold.

† Yes everyone's baseline temperature is slightly different, but that just makes the decimal on the Fahrenheit scale look even sillier. And fever definitions are also keyed off of Celsius: 37º to 38º is "low grade". Sure, it's an arbitrary convention but it's the one adopted around the world, including in the US (98.6 to 100.4).

Whether it's off by a degree or 2 doesn't matter (as you said body temperature varies)

But why is 100 ~= body temperature more useful than 100 = boiling water?

Why is 50 being kind of cold more useful than 10?

I don't get this "Fahrenheit numbers are more useful/convenient/understandable" argument

As a human person, temperature relative to my body is more useful than the boiling point of water at ~100 kpa.

Anyways, in Titan's atmosphere water boils at ~110 C, so much for "100 = boiling water".

Absolutely. Those of us outside the US have terrible trouble with temperatures. We're constantly confused. Just the other day I was trying to measure something to a tenthousandth of a degree and I said to my friend "I wish we used Fahrenheit — they only have integer temperatures".

> Fahrenheit is more appropriate unit because it represents human compatible temperature

0 being the freezing point of a mix of water, ice and ammonium chloride and 100 being almost the average human body temperature - or to put it another way, "a random number fixed to a variable". Neither of these are things I can instinctively understand as a human.

Celcius on the other hand uses extremely hard to grasp concepts for a human, like the freezing point of water and at the upper end of the scale (is it a random number? no, it's) the boiling point of water - both things a person is likely to encounter in their lifetime, possibly even more than once.

https://www.youtube.com/watch?v=nROK4cjQVXM

0 degrees is "really fucking cold outside" and 100 degrees is "really fucking hot outside". Celsius resorts to negative numbers even for a normal snowy day while wasting about half of the positive two-digit numbers for temperatures that have never been recorded on Earth. It's a terrible scale for weather.

Having negative numbers for when water is in a different state is quite a convenient representation, especially for weather. To follow your scale, -50ºC is really cold (polar weather) and +50 is really hot (desert weather). Yes there are places hotter and colder but it's a continuum with convenient points that stick out less than a phase change of the liquid which is so integral to life, be it human, fauna or flora.

Even -40°C is very far outside the range of where virtually anybody lives, though. It's equivalent to -40°F. Most places never reach that temperature. The problem with a 100-degree scale centered around the freezing point of water is that the freezing point of water actually is approximately 1/3 of the way along the scale between "exceptionally cold" and "exceptionally hot"--it isn't a midpoint--and so by the time you reach -50°C you're solidly in the realm of "potentially record-setting low temperature for most places on Earth". The more analogous range is -20°C to 40°C, and that's with 2-3 degrees of rounding on both sides.

The freezing point of water is an important temperature, but it's not a temperature that should be treated as being "off the scale" or even at the edge of the scale, which is what the number 0 implies. Being able to represent most survivable air temperatures with unsigned 2-digit numbers is more convenient than not having to remember the freezing point of water, as is the heuristic of any exception to that rule representing an exceptional weather condition.

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