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Comment by philwelch | Hacker News Reader

I don't see how centigrade would actually help. I agree that it's better for scientific measurements (if not as good as Kelvins) but the typical Fahrenheit range is much better suited for weather conditions than centigrade from a usability standpoint. The typical weather conditions on the inhabited parts of the earth don't range much further than 0-100, whereas centrigrade can't represent any kind of legitimately wintry conditions without resorting to negative numbers and everything above 50 is completely unused. From a usability standpoint, it makes sense that typical temperatures should be distributed along a 100 point scale, and that only genuine extremes should exceed the ends of that. Fahrenheit meets that requirement; centigrade doesn't.

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If you live in a climate where you have real winter, then being able to tell the difference between freezing and not freezing is very important. -1 means snow from the sky, ice on the roads, lower humidity. +1 means rain, wet roads, and higher humidity. It's a very important divider, which is why it's at a prominent place on the Celsius scale, unlike the Fahrenheit one where it's between 32 and 34.

I don't think it's a coincidence that Anders Celsius lived further north than Daniel Gabriel Fahrenheit. :-)

I'm not fond of the tradeoff between not having to remember the number 32 and having to use a sign bit for half the year. Frankly you're not totally safe from ice until 35 or so, and it's useful to have a marker around 0 or so that just says "your face will fall off". Likewise, it's nice to have a convenient marker around 100 for "your face will melt off". 0 and 100 are good for extreme ends of a range, not so much for middle values.

But -1 doesn't mean that. A myriad of factors comes into play before you can tell if there will be ice on the road, not least the temperature of the road it self. It takes prolonged periods of cold to chill a road down to where it can sustain ice. Conversely, after a night with hard freezing, ice can remain on the road for hours, even as temperatures climb into decidedly balmy territory. In Denmark people rely on weather forecast warnings on the radio for this more than intuitive reading of the thermometer.

That is an interesting way of putting it. I (metric since birth) find that zero degrees centigrade is a very strong signal that things are getting cooler or warmer. I would think that, from a usability point of view, zero is easier to retain than thirty two (assuming that ice is an important factor in your neck of the woods).

I dunno about that - been metric all my life and I know the difference between 23 and 28 degrees C. Since it's something you generally grow up learning about, the practical usability (by lay users) in terms of dealing with estimating temperatures is something that is picked up along the way too.

Additionally, weather reports will usually qualify the temperatures (with things like "warm and sunny" or "hot" or whatever), which is needed regardless of measurement - 25 degrees C in humid conditions is a very different "feel" from 25 degrees C in dry conditions. Add in wind chill/warm factors and temperature by itself is not actually that useful by itself to determine the weather practically.

Everywhere I've lived, humidity is a feature of climate and not weather. If you live someplace dry, it's dry. Heat is a dry heat, cold is a dry cold. So you actually can take temperature as the most significant variable.

I grew up in Sydney, Australia, where humidity is reasonably variable. And you can definitely feel it some days, definitely not others.

You can see some graphs here: http://www.gids.nl/sydney/weather/ - notice how it fluctuates between about 25 and 100% humidity, particularly on the month-by-month graph.

Wow! You're right, I didn't realize some places had that much variability in their humidity. Even over the course of a day it ranges quite a bit!

Glad I could help! Weather conditions are so different across the globe - I came last week from London where everyone was sweltering in 28 deg C heat to Sydney where 28 deg C was only just comfortable in a t-shirt, and I felt like I should take a jacket with me just in case it got a little chillier. I can only put that down to other aspects - humidity, wind, cloud cover, etc. rather than simply raw temperature.

That's just a convention. I don't much care if temperature today will be 28 C or 28.5 C, it doesn't matter and it varies anyway. We really don't need that much precision in temperatures.

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