3 ms·

Would cooling it help to reduce the amount of pressure the atmosphere has? Isn't the pressure on the surface something like 95 times that of earth.

by stx 6y ago

virmundi 6y ago
Which is also largely why it’s hot.
eggsome 6y ago
Surely it would cool below the point where Co2 becomes solid (most of the atmosphere is Co2). Imagine walking around on fields of Co2 :)
- debo_ 6y ago
  Reminds me of the short story "A Pail of Air".
  - jamiek88 6y ago
    I read that short story as a kid and tried to remember the title for years, you’ve just scratched that itch!
- kabdib 6y ago
  I read an SF story a few years ago where the idea was to sequester the carbon of Venus into blocks of diamond. A minor bit of (ahem) atmosphere in a pretty good novel . . . just don't remember the title.
- 01100011 6y ago
  You beat me to it. Just posted a comment saying the same thing. I think if we solidified the CO2 we would have an easier time dealing with it, but IDK. Then again, we might be able to get to work now by just suspending some blimps in the upper atmosphere. They could use solar energy to sequester the CO2 and start lowering the pressure & temperature.
meepmorp 6y ago
PV=nRT, so yes, reducing the temperature would reduce the atmospheric pressure. Edit: wasn't thinking at all about the volume
- solarhoma 6y ago
  Volume would vary in this instance, too, right?
- woofie11 6y ago
  Or volume. More likely volume, since the pressure is just a function of how much stuff is above me.
- robbmorganf 6y ago
  While the equation you give is valid, I think it is probably not that useful given the "volume" is open to space and so we can't solve this equation. I think more useful is a static equilibrium, specifically that d(pressure)/d(altitude)=-density(pressure,temperature)*gravity(altitude). Which gives you roughly an exponential falloff with altitude if you assume gravity is constant (which is fine if it's a small fraction of planet radius) and molecular weight and temperature are constant (that's definitely not true but oh well) EDIT: for the question asker: reducing the temperature would have a first order effect of just making the density gradient steeper, but surface pressure would be the same. The second order effect might be that the surface absorbs some CO2, which would actually reduce surface pressure.
- bernulli 6y ago
  It's not, though, the Venus atmosphere does not behave like an ideal gas all around, it transitions into a supercritical dense liquid towards the ground.
elihu 6y ago
I think the average pressure should stay about the same because the mass stays the same, but if it compresses maybe the pressure goes up in low-lying areas and goes down at higher altitudes. According to Wikipedia, CO2 can liquify at around 5 atmospheres, though it has to be pretty cold at that pressure. The phase diagram shows it as a liquid around room temperature (300K or so) at about a hundred atmospheres. Which makes a liquid ocean of CO2 is at least sort of plausible if the temperature drops far enough. https://en.wikipedia.org/wiki/Carbon_dioxide#/media/File:Carbon_dioxide_pressure-temperature_phase_diagram.svg https://en.wikipedia.org/wiki/Carbon_dioxide#/media/File:Car...
emtel 6y ago
No, and the other comments about gas laws and volume are overthinking it a bit. Pressure at the surface is caused by the weight of the atmosphere. On earth, a column of air extending from sea level to space, with cross sectional area one square inch, weighs 15 pounds. Neither the temperature or volume of the atmosphere changes its weight. (Ok, I suppose a hotter atmosphere has more volume and extends higher into space and weighs slightly less, as it is farther from the planet on average, but I assume that’s a fairly negligible effect)
- saiya-jin 6y ago
  You forget things like condensation/solidification of things like CO2 in lower temperatures, so atmosphere composition would change dramatically, and so would overall 'weight' of the column to space you mention. Anyway as other mention it doesn't change that much in survability, having 116 days long single Venus-day would mean temperature differences would be extreme, probably in hundreds of degrees.

Would cooling it help to reduce the amount of pressure the atmosphere has? Isn't the pressure on the surface something like 95 times that of earth.

by stx 6y ago

Would cooling it help to reduce the amount of pressure the atmosphere has? Isn't the pressure on the surface something like 95 times that of earth.

virmundi 6y ago

Which is also largely why it’s hot.

eggsome 6y ago

Surely it would cool below the point where Co2 becomes solid (most of the atmosphere is Co2). Imagine walking around on fields of Co2 :)

debo_ 6y ago
Reminds me of the short story "A Pail of Air".
- jamiek88 6y ago
  I read that short story as a kid and tried to remember the title for years, you’ve just scratched that itch!
kabdib 6y ago
I read an SF story a few years ago where the idea was to sequester the carbon of Venus into blocks of diamond. A minor bit of (ahem) atmosphere in a pretty good novel . . . just don't remember the title.
01100011 6y ago
You beat me to it. Just posted a comment saying the same thing. I think if we solidified the CO2 we would have an easier time dealing with it, but IDK. Then again, we might be able to get to work now by just suspending some blimps in the upper atmosphere. They could use solar energy to sequester the CO2 and start lowering the pressure & temperature.

meepmorp 6y ago

PV=nRT, so yes, reducing the temperature would reduce the atmospheric pressure. Edit: wasn't thinking at all about the volume

solarhoma 6y ago
Volume would vary in this instance, too, right?
woofie11 6y ago
Or volume. More likely volume, since the pressure is just a function of how much stuff is above me.
robbmorganf 6y ago
While the equation you give is valid, I think it is probably not that useful given the "volume" is open to space and so we can't solve this equation. I think more useful is a static equilibrium, specifically that d(pressure)/d(altitude)=-density(pressure,temperature)*gravity(altitude). Which gives you roughly an exponential falloff with altitude if you assume gravity is constant (which is fine if it's a small fraction of planet radius) and molecular weight and temperature are constant (that's definitely not true but oh well) EDIT: for the question asker: reducing the temperature would have a first order effect of just making the density gradient steeper, but surface pressure would be the same. The second order effect might be that the surface absorbs some CO2, which would actually reduce surface pressure.
bernulli 6y ago
It's not, though, the Venus atmosphere does not behave like an ideal gas all around, it transitions into a supercritical dense liquid towards the ground.

elihu 6y ago

I think the average pressure should stay about the same because the mass stays the same, but if it compresses maybe the pressure goes up in low-lying areas and goes down at higher altitudes. According to Wikipedia, CO2 can liquify at around 5 atmospheres, though it has to be pretty cold at that pressure. The phase diagram shows it as a liquid around room temperature (300K or so) at about a hundred atmospheres. Which makes a liquid ocean of CO2 is at least sort of plausible if the temperature drops far enough. https://en.wikipedia.org/wiki/Carbon_dioxide#/media/File:Carbon_dioxide_pressure-temperature_phase_diagram.svg https://en.wikipedia.org/wiki/Carbon_dioxide#/media/File:Car...

emtel 6y ago

No, and the other comments about gas laws and volume are overthinking it a bit. Pressure at the surface is caused by the weight of the atmosphere. On earth, a column of air extending from sea level to space, with cross sectional area one square inch, weighs 15 pounds. Neither the temperature or volume of the atmosphere changes its weight. (Ok, I suppose a hotter atmosphere has more volume and extends higher into space and weighs slightly less, as it is farther from the planet on average, but I assume that’s a fairly negligible effect)

saiya-jin 6y ago
You forget things like condensation/solidification of things like CO2 in lower temperatures, so atmosphere composition would change dramatically, and so would overall 'weight' of the column to space you mention. Anyway as other mention it doesn't change that much in survability, having 116 days long single Venus-day would mean temperature differences would be extreme, probably in hundreds of degrees.