11 ms·

"The average temperatures on the Victoria line have risen by almost seven degrees since 2013 – nearly a 30% increase. Conversely, the increase in the average

"The average temperatures on the Victoria line have risen by almost seven degrees since 2013 – nearly a *30%* increase. Conversely, the increase in the average annual temperatures across all Underground lines from 2013 to 2024 was merely *seven percent*, placing Victoria’s temperature rise vastly above that." Using percentages to talk about changes in non-Kelvin temperatures is crazy.

OJFord 1y ago
It would definitely be crazy in Fahrenheit, but in centigrade I think it makes some sort of intuitive (if not scientific) sense. (Together with the sea-level assumption we always make in casual temperature discussion anyway.)
- azernik 1y ago
  It makes just as much intuitive sense in Fahrenheit as it does in centigrade.
  - perching_aix 1y ago
    Why? The slope of the Fahrenheit scale is different to the Celsius and Kelvin scales, but the slope of the latter two does match.
    - meindnoch 1y ago
      Ok. Then please explain what % does the temperature rise when going from 0 Celsius to 5 Celsius!
      - stephencanon 1y ago
        Or -1 to 1 Celsius, for that matter.
        chihuahua 1y ago
        Obviously it's -200%, which means that going from -1C to 1C is a drastic decrease in warmness!
    - azernik 1y ago
      The slope of the Fahrenheit scale matches that of the Rankine scale. I would still say that the in the Rankine scale percentage increases make sense, and Fahrenheit changes to not. The thing that matters isn't the slope, but the zero point; "X% farther from absolute zero" is a useful measurement, "X% farther from an arbitrary zero point" is not. Especially when negative or zero temperatures are involved.
    - lolinder 1y ago
      The slope of the scales has no bearing on whether percentages are meaningful here. The problem with both systems when it comes to percentages is that neither system has 0 set to a natural 0. This leads to an entirely arbitrary point on the scale where decreases in the unit will approach a 100% difference and then suddenly start decreasing again. If anything Fahrenheit should be less insane because at least the artificial 0 is likely to stay much further away in the data they're quantifying so the percentages stay reasonable.
      - perching_aix 1y ago
        Ah right, okay, that makes sense.
    - detourdog 1y ago
      Early measurements were done by individuals and they were idiosyncratic to the process of discovery/calibration. Kelvin is refined measurements used to relate to a wider scale of temperatures. Celsius is a metric human scale subset of Kelvin.
  - detourdog 1y ago
    Reading this quote made me finally realize why the name centigrade exists. It’s a gradient scale of 100.
    - tailspin2019 1y ago
      Reading this comment about the previous quote made me finally realize why the name centigrade exists.
  - tim333 1y ago
    Maybe because I was brought up with centigrade it makes more sense to me. The centigrade number is how far you are from water freezing. If it goes up 100% then you are twice as far away. I'm not aware that doubling the fahrenheit number has a similar easy to understand meaning?
    - ars 1y ago
      > The centigrade number is how far you are from water freezing The Fahrenheit scale is how far your are from your own body temperature. It was designed that 100 is the temperature of a human. (Adjusted later to 98.6 due to inaccuracies.) 0 was designed to be as cold as you can get with ice and salt (also ended up being slightly inaccurate). > Maybe because I was brought up with centigrade it makes more sense to me. Yup. People brought up on Fahrenheit think it is superior. For temperature neither argument is objectively better. (In contrast to imperial distance measurement with non-powers of 10 and factions, where there are good arguments against it, with temperature both scales are ultimately arbitrary.)
      - skissane 1y ago
        > For temperature neither argument is objectively better. I think Celsius is objectively better in that: (1) its endpoints–freezing and boiling point of water–are more natural / less arbitrary / more fundamental than Fahrenheit's–coldest temperature you can reach with salt and ice to average human body temperature. Water is a fundamental substance to all known life; the freezing point of pure water is much more fundamental than the freezing point of a water + NaCl mixture (actually apparently Fahrenheit used ammonium chloride not sodium chloride, which is arguably even more arbitrary than sodium chloride would be). If you imagine some extraterrestrial civilisation independently invents a temperature scale, they'd be more likely to come up with something close to Celsius than something close to Fahrenheit (2) while both scales contain some error in that the nominal value of their endpoints differs from the real value, the error is greater for Fahrenheit (3) According to Wikipedia, Fahrenheit didn't have 100 degrees between his two endpoints, he originally had 90 then increased it to 96 – given base 10 is the standard number base used by humans, 100 divisions is less arbitrary than 90 or 96 (4) nowadays, all other temperature scales are officially defined in terms of Kelvin – and Celsius has a simpler relationship to Kelvin than Fahrenheit does (for Celsius it is purely an additive offset, for Fahrenheit it involves both addition and multiplication) (5) conforming to the global standard is objectively better than sticking with an alternative which lacks clearcut advantges
- strken 1y ago
  In both it makes a sort of intuitive sense. 7% of the way from freezing to boiling is a meaningful way to visualise temperature; 7% of the way from ice melting in a bath of salt to slightly above Mrs Fahrenheit's armpit temperature is also meaningful, although perhaps a little idiosyncratic. Edit: this comment was deeply stupid for obvious reasons and I regret trying to interact with other people when I should be asleep.
  - movpasd 1y ago
    The issue is a percentage of a Celsius value is not that. For example, an increase from 1°C to 2°C is a "100% increase", but is only 1 percentage point from freezing to boiling.
    - OJFord 1y ago
      You could say things like that with anything in percentages? 100% increase in your pension from 100k to 200k is only 10% (increase, to 20% total) of your target 1M, or whatever.
      - eCa 1y ago
        But in your example, the 10% has nothing at all to do with the increase of 100%. If your ”whatever” target instead was 50k, is the argument that going from 100k to 200k would be 400%?
        OJFord 1y ago
        Yes? I didn't see any link in comment I replied to between 100% and 100deg besides it happening to be the same number - I already changed that to 1M, changing it to 50k no different either. If the argument was saying there's something special about 100% being 100 quantity then.. no? I don't really know where to go from there, what I said still holds with a 100k target, but I'm not going to be able to give 'another' example where the 100 quantity is meaningful because it isn't for degrees either. It's the freezing point at 0 that makes it work better for centigrade than Fahrenheit, imo.
casenmgreen 1y ago
I logged in just to give this an upvote :-)
Y_Y 1y ago
Feynman was complaining about this error appearing in textbooks back in the sixties[0]. The trouble (of course) is that Celsius properly is not a proper unit, but a "scale", or a "unit of difference" (equal to kelvin), or even torsor[1]. The trouble with the kelvin here is that if you see the 7 kelvin increase as a proportion of the 295K starting temperature the you only get a 2% increase. Nobody is going to buy your newspaper if you're putting up weak numbers like that. [0] https://mathematicalcrap.com/2024/03/05/the-feynman-story/ https://mathematicalcrap.com/2024/03/05/the-feynman-story/ [1] https://math.ucr.edu/home/baez/torsors.html https://math.ucr.edu/home/baez/torsors.html
- azernik 1y ago
  Then just don't use percentages, and rely on people realizing that a 7 degree difference is big!
- buran77 1y ago
  To make matters worse, not all ranges and percentages on that scale are equal, whether they're the same in absolute or relative terms. Humans have a narrow relevant "operational" temperature band. Even 20 degrees between 10-30C feel like nothing compared to the 5 degrees between 37-42C.
  - hnlmorg 1y ago
    You’re right in principle but that’s probably the worst example you could have given. So bad an example that I think it could easily be argued to disprove your point.
    - deleted 1y ago
      [deleted]
    - paganel 1y ago
      For us people not living in Arabia or South Texas the difference between 37 and 42 Celsius is indeed quite important. 37 feels pretty hot, but yet livable, while 42 (and even 40 for me) means that nothing non-urgent should bring me out of the house.
moomin 1y ago
I don’t know if I’m worried about it. While the measurement makes little scientific sense it makes intuitive sense, and, importantly, the intuitive implications are the scientific implications. It’s a huge increase, if not for the reasons they describe.
nelgaard 1y ago
And they manage to make it even more crazy by also comparing it to average external temperatures. == The Victoria Line average temperature in August last year was 60% higher in temperature than the average external temperature that month, measured at 19.5 degrees. == Certainly for January it must have been hundreds of percent higher. And what would the numbers be for e.g., the Moscow metro in winter months where the average outside temperature is negative?
StopDisinfo910 1y ago
Is it? I think it puts the Victoria rise in perspective to the other lines quite effectively. Everyone knows where the zero is in Celsius using countries anyway and days in the negative are so rare in the UK you can discount them (plus they are none inside the tube).
zeristor 1y ago
Yikes. I posted this, and I missed that, something I realised soon into my first year physics degree lab. I learnt more than just dipping calculators in liquid nitrogen for fun. I apologise.
brookst 1y ago
Yep. That 30% is a bad use of statistics. 28 degrees Celsius is not 30% warmer than 21 degrees Celsius. This same stat rendered in Fahrenheit would say 70 degrees -> 82 degrees, or 17%. In kelvin it would be 294 -> 301, or 2.3% Or we could invent a new measure indexed to Celsius but offset by 20 degrees, and declare a 1 -> 8 change, a whopping 700%.
- kevin_thibedeau 1y ago
  You see the opposite effect with reporting on the DJIA, where a 500 point move is treated like a big event even though it's is not nearly as significant today as it was 30 years ago. They ignore the more relevant percentage change in favor of the more sensational representation.
  - AdamN 1y ago
    That's not statistics as much as sensationalism. Every morning on WSJ at about 7am you'll see a 'live' update about how the markets and futures are in a 'selloff' or 'surging' even if the percentages are like 0.3% in either direction.
- dzhiurgis 1y ago
  But 28C or 82F is swelteringly hot in Britain so it kinda makes sense even it's incorrect.
  - notahacker 1y ago
    Yeah. It's obviously incorrect in the sense celsius has no meaning as an absolute temperature scale and so its not 30% more anything, but in terms of colloquial meaning the average Brit probably does see it as ~30% further along an indoor temperature scale from "someone put the heating on please" to "crikey, it's sweltering in here"
  - blueflow 1y ago
    This is not okay. If it makes sense for you, your sense for percentages is wrong.
AStonesThrow 1y ago
So how many decibels louder is it now?
nssnsjsjsjs 1y ago
And only in specific contexts with Kelvin. If you go from freezing water to boiling, it's only 37% hotter!
hkt 1y ago
Maybe the right thing to do is to measure from ideal room temperature? From zero doesn't make any sense but setting an anchor temperature makes sense. This is done when people rate the efficiency of home heating: SCOP is a function of the heat pump's ability to hit a particular temperature, for instance. I'd guess the baseline temperature on the tube should be 21C maximum. Percentages don't make sense here, but 7C over the target temperature (for instance) is pretty bad in those terms. I'd be surprised if TfL hadn't set that somewhere. Also worthy of note is that it sounds like the tube is a prime source of heat for a district heating system. Win win, perhaps.
qubex 1y ago
I came here to say this. It rankled me no end. Good to see that this is the top comment because we’re a scientifically literate crowd.

"The average temperatures on the Victoria line have risen by almost seven degrees since 2013 – nearly a *30%* increase. Conversely, the increase in the average

OJFord 1y ago

It would definitely be crazy in Fahrenheit, but in centigrade I think it makes some sort of intuitive (if not scientific) sense. (Together with the sea-level assumption we always make in casual temperature discussion anyway.)

azernik 1y ago
It makes just as much intuitive sense in Fahrenheit as it does in centigrade.
- perching_aix 1y ago
  Why? The slope of the Fahrenheit scale is different to the Celsius and Kelvin scales, but the slope of the latter two does match.
  - meindnoch 1y ago
    Ok. Then please explain what % does the temperature rise when going from 0 Celsius to 5 Celsius!
    - stephencanon 1y ago
      Or -1 to 1 Celsius, for that matter.
      - chihuahua 1y ago
        Obviously it's -200%, which means that going from -1C to 1C is a drastic decrease in warmness!
  - azernik 1y ago
    The slope of the Fahrenheit scale matches that of the Rankine scale. I would still say that the in the Rankine scale percentage increases make sense, and Fahrenheit changes to not. The thing that matters isn't the slope, but the zero point; "X% farther from absolute zero" is a useful measurement, "X% farther from an arbitrary zero point" is not. Especially when negative or zero temperatures are involved.
  - lolinder 1y ago
    The slope of the scales has no bearing on whether percentages are meaningful here. The problem with both systems when it comes to percentages is that neither system has 0 set to a natural 0. This leads to an entirely arbitrary point on the scale where decreases in the unit will approach a 100% difference and then suddenly start decreasing again. If anything Fahrenheit should be less insane because at least the artificial 0 is likely to stay much further away in the data they're quantifying so the percentages stay reasonable.
    - perching_aix 1y ago
      Ah right, okay, that makes sense.
  - detourdog 1y ago
    Early measurements were done by individuals and they were idiosyncratic to the process of discovery/calibration. Kelvin is refined measurements used to relate to a wider scale of temperatures. Celsius is a metric human scale subset of Kelvin.
- detourdog 1y ago
  Reading this quote made me finally realize why the name centigrade exists. It’s a gradient scale of 100.
  - tailspin2019 1y ago
    Reading this comment about the previous quote made me finally realize why the name centigrade exists.
- tim333 1y ago
  Maybe because I was brought up with centigrade it makes more sense to me. The centigrade number is how far you are from water freezing. If it goes up 100% then you are twice as far away. I'm not aware that doubling the fahrenheit number has a similar easy to understand meaning?
  - ars 1y ago
    > The centigrade number is how far you are from water freezing The Fahrenheit scale is how far your are from your own body temperature. It was designed that 100 is the temperature of a human. (Adjusted later to 98.6 due to inaccuracies.) 0 was designed to be as cold as you can get with ice and salt (also ended up being slightly inaccurate). > Maybe because I was brought up with centigrade it makes more sense to me. Yup. People brought up on Fahrenheit think it is superior. For temperature neither argument is objectively better. (In contrast to imperial distance measurement with non-powers of 10 and factions, where there are good arguments against it, with temperature both scales are ultimately arbitrary.)
    - skissane 1y ago
      > For temperature neither argument is objectively better. I think Celsius is objectively better in that: (1) its endpoints–freezing and boiling point of water–are more natural / less arbitrary / more fundamental than Fahrenheit's–coldest temperature you can reach with salt and ice to average human body temperature. Water is a fundamental substance to all known life; the freezing point of pure water is much more fundamental than the freezing point of a water + NaCl mixture (actually apparently Fahrenheit used ammonium chloride not sodium chloride, which is arguably even more arbitrary than sodium chloride would be). If you imagine some extraterrestrial civilisation independently invents a temperature scale, they'd be more likely to come up with something close to Celsius than something close to Fahrenheit (2) while both scales contain some error in that the nominal value of their endpoints differs from the real value, the error is greater for Fahrenheit (3) According to Wikipedia, Fahrenheit didn't have 100 degrees between his two endpoints, he originally had 90 then increased it to 96 – given base 10 is the standard number base used by humans, 100 divisions is less arbitrary than 90 or 96 (4) nowadays, all other temperature scales are officially defined in terms of Kelvin – and Celsius has a simpler relationship to Kelvin than Fahrenheit does (for Celsius it is purely an additive offset, for Fahrenheit it involves both addition and multiplication) (5) conforming to the global standard is objectively better than sticking with an alternative which lacks clearcut advantges
strken 1y ago
In both it makes a sort of intuitive sense. 7% of the way from freezing to boiling is a meaningful way to visualise temperature; 7% of the way from ice melting in a bath of salt to slightly above Mrs Fahrenheit's armpit temperature is also meaningful, although perhaps a little idiosyncratic. Edit: this comment was deeply stupid for obvious reasons and I regret trying to interact with other people when I should be asleep.
- movpasd 1y ago
  The issue is a percentage of a Celsius value is not that. For example, an increase from 1°C to 2°C is a "100% increase", but is only 1 percentage point from freezing to boiling.
  - OJFord 1y ago
    You could say things like that with anything in percentages? 100% increase in your pension from 100k to 200k is only 10% (increase, to 20% total) of your target 1M, or whatever.
    - eCa 1y ago
      But in your example, the 10% has nothing at all to do with the increase of 100%. If your ”whatever” target instead was 50k, is the argument that going from 100k to 200k would be 400%?
      - OJFord 1y ago
        Yes? I didn't see any link in comment I replied to between 100% and 100deg besides it happening to be the same number - I already changed that to 1M, changing it to 50k no different either. If the argument was saying there's something special about 100% being 100 quantity then.. no? I don't really know where to go from there, what I said still holds with a 100k target, but I'm not going to be able to give 'another' example where the 100 quantity is meaningful because it isn't for degrees either. It's the freezing point at 0 that makes it work better for centigrade than Fahrenheit, imo.

casenmgreen 1y ago

I logged in just to give this an upvote :-)

Y_Y 1y ago

Feynman was complaining about this error appearing in textbooks back in the sixties[0]. The trouble (of course) is that Celsius properly is not a proper unit, but a "scale", or a "unit of difference" (equal to kelvin), or even torsor[1]. The trouble with the kelvin here is that if you see the 7 kelvin increase as a proportion of the 295K starting temperature the you only get a 2% increase. Nobody is going to buy your newspaper if you're putting up weak numbers like that. [0] https://mathematicalcrap.com/2024/03/05/the-feynman-story/ https://mathematicalcrap.com/2024/03/05/the-feynman-story/ [1] https://math.ucr.edu/home/baez/torsors.html https://math.ucr.edu/home/baez/torsors.html

azernik 1y ago
Then just don't use percentages, and rely on people realizing that a 7 degree difference is big!
buran77 1y ago
To make matters worse, not all ranges and percentages on that scale are equal, whether they're the same in absolute or relative terms. Humans have a narrow relevant "operational" temperature band. Even 20 degrees between 10-30C feel like nothing compared to the 5 degrees between 37-42C.
- hnlmorg 1y ago
  You’re right in principle but that’s probably the worst example you could have given. So bad an example that I think it could easily be argued to disprove your point.
  - deleted 1y ago
    [deleted]
  - paganel 1y ago
    For us people not living in Arabia or South Texas the difference between 37 and 42 Celsius is indeed quite important. 37 feels pretty hot, but yet livable, while 42 (and even 40 for me) means that nothing non-urgent should bring me out of the house.

moomin 1y ago

I don’t know if I’m worried about it. While the measurement makes little scientific sense it makes intuitive sense, and, importantly, the intuitive implications are the scientific implications. It’s a huge increase, if not for the reasons they describe.

nelgaard 1y ago

And they manage to make it even more crazy by also comparing it to average external temperatures. == The Victoria Line average temperature in August last year was 60% higher in temperature than the average external temperature that month, measured at 19.5 degrees. == Certainly for January it must have been hundreds of percent higher. And what would the numbers be for e.g., the Moscow metro in winter months where the average outside temperature is negative?

StopDisinfo910 1y ago

Is it? I think it puts the Victoria rise in perspective to the other lines quite effectively. Everyone knows where the zero is in Celsius using countries anyway and days in the negative are so rare in the UK you can discount them (plus they are none inside the tube).

zeristor 1y ago

Yikes. I posted this, and I missed that, something I realised soon into my first year physics degree lab. I learnt more than just dipping calculators in liquid nitrogen for fun. I apologise.

brookst 1y ago

Yep. That 30% is a bad use of statistics. 28 degrees Celsius is not 30% warmer than 21 degrees Celsius. This same stat rendered in Fahrenheit would say 70 degrees -> 82 degrees, or 17%. In kelvin it would be 294 -> 301, or 2.3% Or we could invent a new measure indexed to Celsius but offset by 20 degrees, and declare a 1 -> 8 change, a whopping 700%.

kevin_thibedeau 1y ago
You see the opposite effect with reporting on the DJIA, where a 500 point move is treated like a big event even though it's is not nearly as significant today as it was 30 years ago. They ignore the more relevant percentage change in favor of the more sensational representation.
- AdamN 1y ago
  That's not statistics as much as sensationalism. Every morning on WSJ at about 7am you'll see a 'live' update about how the markets and futures are in a 'selloff' or 'surging' even if the percentages are like 0.3% in either direction.
dzhiurgis 1y ago
But 28C or 82F is swelteringly hot in Britain so it kinda makes sense even it's incorrect.
- notahacker 1y ago
  Yeah. It's obviously incorrect in the sense celsius has no meaning as an absolute temperature scale and so its not 30% more anything, but in terms of colloquial meaning the average Brit probably does see it as ~30% further along an indoor temperature scale from "someone put the heating on please" to "crikey, it's sweltering in here"
- blueflow 1y ago
  This is not okay. If it makes sense for you, your sense for percentages is wrong.

AStonesThrow 1y ago

So how many decibels louder is it now?

nssnsjsjsjs 1y ago

And only in specific contexts with Kelvin. If you go from freezing water to boiling, it's only 37% hotter!

hkt 1y ago

Maybe the right thing to do is to measure from ideal room temperature? From zero doesn't make any sense but setting an anchor temperature makes sense. This is done when people rate the efficiency of home heating: SCOP is a function of the heat pump's ability to hit a particular temperature, for instance. I'd guess the baseline temperature on the tube should be 21C maximum. Percentages don't make sense here, but 7C over the target temperature (for instance) is pretty bad in those terms. I'd be surprised if TfL hadn't set that somewhere. Also worthy of note is that it sounds like the tube is a prime source of heat for a district heating system. Win win, perhaps.

qubex 1y ago

I came here to say this. It rankled me no end. Good to see that this is the top comment because we’re a scientifically literate crowd.