8 ms·

There is probably still a limit, because you need to breath fresh air. A human breathes at about 6 liter/minute. In terms of mass and converting to seconds, th

There is probably still a limit, because you need to breath fresh air. A human breathes at about 6 liter/minute. In terms of mass and converting to seconds, that's 0.1293 gram/second. Heat capacity of air is 0.7 Joules per gram per kelvin. So the power needed to heat up incoming air 1 degree kelvin is 0.1293*0.7=0.09051 Watt. Times a hundred (-60C to body temperature), that's 9 watt. Since the human body produces about 100 watt of heat in total, that's maybe still feasible. But having that percentage of your body heat being drawn out through your airways and lungs is getting dangerous. And it gets colder on Antarctica. And exertion will speed up breathing. Researchers on Antarctica apparently deal with by breathing through snorkels that pass through their jacket, so that the rest of the body can help to heat up the air: https://www.newscientist.com/article/dn24731-coldest-place-on-earth-tucked-in-antarctic-ice-pocket/ https://www.newscientist.com/article/dn24731-coldest-place-o... Perhaps it would also be possible to recover some of the heat in exhaled air, by passing it through a heat exchanger for the incoming air.

euroderf 4y ago
Sort of like an Arrakeen stillsuit but for heat.
joshvm 4y ago
I'd stress that this is at the colder locations on the continent, not the South Pole. The bigger challenge is actually the altitude. Physiological altitude can (occasionally) hit 14k ft at the Pole and those days are rough. Temperature bottoms out around -100 F/-72 C and if you're outside, you're breathing through a gaiter/balaclava). That's sufficient to warm it up. I don't recall there ever being a situation (even that cold) when breathing was challenging due to the temperature alone. Weird fact: you can't whistle when it gets that cold. I don't know if it's something to do with the immediate dense condensation or the temperature. It's not the pressure or the humidity, because indoors is OK.
- AnimalMuppet 4y ago
  Can you explain how physiological altitude works? I've never heard of it.
  - foobarbecue 4y ago
    This is referring to the fact that when you go up in the atmosphere over high latitudes (e.g. poles), air pressure drops faster than over the equator. So when polar people talk about "physiological altitude" they usually mean what altitude at the equator has the same air pressure as the altitude you're at down south. It will be a few thousand feet higher. Also, barometric pressure changes with weather can increase the "equivalent altitude," which is why the above commenter is saying it can "sometimes" reach 14 thousand feet. Storm fronts are generally low pressure.
  - mlindner 4y ago
    To add on to what foobarbecue said, this I believe is because the earth is spinning, so just like the Earth is not a sphere (it's an oblate spheroid), the atmosphere is also "dragged" toward the equator than the poles. Sea level pressures at the equators are higher than sea level pressure at the poles because of this.
- foobarbecue 4y ago
  I brought one of those balaclavas where you breathe though a metal heat exchanger the first time I went to Antarctica (living up high on Erebus). Totally unnecessary and not sure it did anything other than slightly impede my breathing.

euroderf 4y ago

Sort of like an Arrakeen stillsuit but for heat.

joshvm 4y ago

I'd stress that this is at the colder locations on the continent, not the South Pole. The bigger challenge is actually the altitude. Physiological altitude can (occasionally) hit 14k ft at the Pole and those days are rough. Temperature bottoms out around -100 F/-72 C and if you're outside, you're breathing through a gaiter/balaclava). That's sufficient to warm it up. I don't recall there ever being a situation (even that cold) when breathing was challenging due to the temperature alone. Weird fact: you can't whistle when it gets that cold. I don't know if it's something to do with the immediate dense condensation or the temperature. It's not the pressure or the humidity, because indoors is OK.

AnimalMuppet 4y ago
Can you explain how physiological altitude works? I've never heard of it.
- foobarbecue 4y ago
  This is referring to the fact that when you go up in the atmosphere over high latitudes (e.g. poles), air pressure drops faster than over the equator. So when polar people talk about "physiological altitude" they usually mean what altitude at the equator has the same air pressure as the altitude you're at down south. It will be a few thousand feet higher. Also, barometric pressure changes with weather can increase the "equivalent altitude," which is why the above commenter is saying it can "sometimes" reach 14 thousand feet. Storm fronts are generally low pressure.
- mlindner 4y ago
  To add on to what foobarbecue said, this I believe is because the earth is spinning, so just like the Earth is not a sphere (it's an oblate spheroid), the atmosphere is also "dragged" toward the equator than the poles. Sea level pressures at the equators are higher than sea level pressure at the poles because of this.
foobarbecue 4y ago
I brought one of those balaclavas where you breathe though a metal heat exchanger the first time I went to Antarctica (living up high on Erebus). Totally unnecessary and not sure it did anything other than slightly impede my breathing.