# What does "ten below" mean in Fahrenheit-using countries?

**URL:** <https://boards.straightdope.com/t/what-does-ten-below-mean-in-fahrenheit-using-countries/590377>\
**Category:** Factual Questions\
**Created:** [July 26, 2011, 1:08pm UTC](https://boards.straightdope.com/t/what-does-ten-below-mean-in-fahrenheit-using-countries/590377 "2011-07-26T13:08:19Z")\
**Posts on this page:** 12\
**Page:** 5

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**Author:** ![ricksummon](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/ricksummon/32/3333_2.png) [@ricksummon](https://boards.straightdope.com/u/ricksummon)\
**Post date:** [July 27, 2011, 4:49am UTC](https://boards.straightdope.com/t/what-does-ten-below-mean-in-fahrenheit-using-countries/590377/81 "2011-07-27T04:49:56Z")

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“Ten below” is, in fact, [hotter](http://en.wikipedia.org/wiki/Negative_temperature) than **any** positive temperature on the Kelvin scale.

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**Author:** ![Boyo\_Jim](https://avatars.discourse-cdn.com/v4/letter/b/87869e/32.png) [@Boyo\_Jim](https://boards.straightdope.com/u/Boyo_Jim)\
**Post date:** [July 27, 2011, 5:24am UTC](https://boards.straightdope.com/t/what-does-ten-below-mean-in-fahrenheit-using-countries/590377/82 "2011-07-27T05:24:56Z")

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> [@ricksummon](#):
>
> “Ten below” is, in fact, [hotter](http://en.wikipedia.org/wiki/Negative_temperature) than **any** positive temperature on the Kelvin scale.

Nonsense. Kelvin is the same as Celsius but with a different zero point.

+32 F = 0 C = 273 K

Kelvin has no negative numbers because it starts at Absolute Zero. But it goes up as high as any other temperature scale goes.

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**Author:** ![panache45](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/panache45/32/64_2.png) [@panache45](https://boards.straightdope.com/u/panache45)\
**Post date:** [July 27, 2011, 10:49am UTC](https://boards.straightdope.com/t/what-does-ten-below-mean-in-fahrenheit-using-countries/590377/83 "2011-07-27T10:49:05Z")

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I’ve always wondered why ≤32F is “freezing.” Why don’t we refer to 32F as “freezing” and \<32F as “frozen.”

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**Author:** ![Colophon](https://avatars.discourse-cdn.com/v4/letter/c/f05b48/32.png) [@Colophon](https://boards.straightdope.com/u/Colophon)\
**Post date:** [July 27, 2011, 11:42am UTC](https://boards.straightdope.com/t/what-does-ten-below-mean-in-fahrenheit-using-countries/590377/84 "2011-07-27T11:42:43Z")

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> [@BDoors](#):
>
> Overnight lows of down to about -4C are not that unusual. The record low in London is -10C.

-21C, actually but that was in January 1795 when London was a rather different place. 🙂

I live about 35 miles from London and it got down to -18C here in winter 1982, when I was five. That’s about half a degree below in Fahrenheit terms… 😛

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**Author:** ![ricksummon](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/ricksummon/32/3333_2.png) [@ricksummon](https://boards.straightdope.com/u/ricksummon)\
**Post date:** [July 27, 2011, 2:12pm UTC](https://boards.straightdope.com/t/what-does-ten-below-mean-in-fahrenheit-using-countries/590377/85 "2011-07-27T14:12:24Z")

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> [@Boyo\_Jim](#):
>
> Nonsense. Kelvin is the same as Celsius but with a different zero point.
> 
> +32 F = 0 C = 273 K
> 
> Kelvin has no negative numbers because it starts at Absolute Zero. But it goes up as high as any other temperature scale goes.

Did you click on the link? [http://en.wikipedia.org/wiki/Negative\_temperature](http://en.wikipedia.org/wiki/Negative_temperature)

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**Author:** ![Floater](https://avatars.discourse-cdn.com/v4/letter/f/dc4da7/32.png) [@Floater](https://boards.straightdope.com/u/Floater)\
**Post date:** [July 27, 2011, 3:02pm UTC](https://boards.straightdope.com/t/what-does-ten-below-mean-in-fahrenheit-using-countries/590377/86 "2011-07-27T15:02:08Z")

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> [@BDoors](#):
>
> The record low in London is -10C.

Do you happen to know when that was? I was in London in December 1976 and it was about that cold then. The Serpentine was covered with ice and there was snow on the ground, but that didn’t deter a couple of boys from playing football dressed in T-shirts and shorts.

I have also had snowfall in London on May 3rd once.

ETA Did you know that Celsius’ original temperature scale had freezing at -100 and boiling at 0? It was later changed by [Carl Wilhelm Scheele](http://en.wikipedia.org/wiki/Carl_Wilhelm_Scheele).

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**Author:** ![SimonMoon5](https://avatars.discourse-cdn.com/v4/letter/s/9f8e36/32.png) [@SimonMoon5](https://boards.straightdope.com/u/SimonMoon5)\
**Post date:** [July 27, 2011, 4:47pm UTC](https://boards.straightdope.com/t/what-does-ten-below-mean-in-fahrenheit-using-countries/590377/87 "2011-07-27T16:47:49Z")

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> [@TriPolar](#):
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> The Fahrenheit scale is much maligned, but it does suit the US temperature range quite well. Temps above 100F and below 0F are very rare,

Well, around here (in Oklahoma), temps above 100F are not rare. We typically get three weeks of such temperature a year and this particular year, it looks like we may get far more than that, getting around two months of such temperatures. We may even break records.

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**Author:** ![Bytegeist](https://avatars.discourse-cdn.com/v4/letter/b/9dc877/32.png) [@Bytegeist](https://boards.straightdope.com/u/Bytegeist)\
**Post date:** [July 27, 2011, 5:23pm UTC](https://boards.straightdope.com/t/what-does-ten-below-mean-in-fahrenheit-using-countries/590377/88 "2011-07-27T17:23:15Z")

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> [@TriPolar](#):
>
> Does anyone know why the term Centigrade was abandoned in favor of Celsius?

To honor Anders Celsius, a Swedish astronomer who defined (almost) the scale that now bears his name — although he had the numbers running in the opposite direction.

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**Author:** ![Shot\_From\_Guns](https://avatars.discourse-cdn.com/v4/letter/s/ccd318/32.png) [@Shot\_From\_Guns](https://boards.straightdope.com/u/Shot_From_Guns)\
**Post date:** [July 27, 2011, 6:00pm UTC](https://boards.straightdope.com/t/what-does-ten-below-mean-in-fahrenheit-using-countries/590377/89 "2011-07-27T18:00:39Z")

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> [@BDoors](#):
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> I have not exhibited any such attitude. Somebody said “below zero, of course” and I acknowledged their answer and then merely explained why it was not “of course” to me.

Not sure why it’s not “of course.” In Celsius, temperatures aren’t “below” because they’re “below freezing” but because they’re “below zero,” which on that scale happens to coincide with freezing. In Fahrenheit, temperatures “below” are also “below zero”–our zero is simply lower than yours.

> [@TriPolar](#):
>
> School was cancelled around here once when the temp hit ‘5 below’.

I really wish school would have been canceled here every time it hit 5 below. Especially if you factored in windchill. I’m not even sure we canceled recess for that (and if you tried to hang around the bathrooms to stay warm, they’d chase you out).

> [@jtgain](#):
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> It’s never gotten colder than 14F in London? That seems amazing to me for some reason, it being as far north as it is.

There are palm trees in Ireland.

> [@panache45](#):
>
> I’ve always wondered why ≤32F is “freezing.” Why don’t we refer to 32F as “freezing” and \<32F as “frozen.”

Actually, when referring to specific temperatures, I hear anything lower than 32 as “below freezing,” while the general descriptor of “freezing” is not meant to be taken literally and, depending on the tolerance of the person speaking, may be well above 32. For example, while waiting in line at the taco cart outside to get some lunch, I thought to myself, “Man, it’s freezing out here,” when the temperature display I can see from the office says something like 63 (i.e., 20 degrees colder than it has been the rest of the week, and 30 degrees colder than last week).

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<div class="post-metadata">

**Author:** ![BDoors](https://avatars.discourse-cdn.com/v4/letter/b/e95f7d/32.png) [@BDoors](https://boards.straightdope.com/u/BDoors)\
**Post date:** [July 27, 2011, 6:22pm UTC](https://boards.straightdope.com/t/what-does-ten-below-mean-in-fahrenheit-using-countries/590377/90 "2011-07-27T18:22:08Z")

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> [@Shot\_From\_Guns](#):
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> In Celsius, temperatures aren’t “below” because they’re “below freezing” but because they’re “below zero,” which on that scale happens to coincide with freezing.

I’m not sure what that assertion is based on. Leaving aside the fact that people here (UK) would not word it as “ten below” (they’d more likely say “minus ten”), how could anyone know whether they meant below zero or below freezing, especially since they are the same thing? Has there been a poll on the matter?

When I initially puzzled about this, I actually thought that Americans had usefully exploited the fact that the Fahrenheit system has two obvious reference points in that temperature range – zero, and freezing – and so they had two ways of expressing low temperatures in relative terms - “ten below” for below freezing, and perhaps “minus ten” for below zero. Whereas we Celsius users can only give temparatures relative to one point. It turns out not to be the case, but that’s what I was wondering about.

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<div class="post-metadata">

**Author:** ![Shot\_From\_Guns](https://avatars.discourse-cdn.com/v4/letter/s/ccd318/32.png) [@Shot\_From\_Guns](https://boards.straightdope.com/u/Shot_From_Guns)\
**Post date:** [July 27, 2011, 7:05pm UTC](https://boards.straightdope.com/t/what-does-ten-below-mean-in-fahrenheit-using-countries/590377/91 "2011-07-27T19:05:05Z")

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Fair enough.

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**Author:** ![Bosstrain](https://avatars.discourse-cdn.com/v4/letter/b/87869e/32.png) [@Bosstrain](https://boards.straightdope.com/u/Bosstrain)\
**Post date:** [July 28, 2011, 3:08pm UTC](https://boards.straightdope.com/t/what-does-ten-below-mean-in-fahrenheit-using-countries/590377/92 "2011-07-28T15:08:40Z")

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when I hear it’s ten below in the weather report, all that means to me is put on a coat, cause it’s cold enough to freeze your balls off out there 🆒

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