UPDATE2: The question has been resolved, please see this new WUWT story on the issue. – Anthony
UPDATE: There is a debate raging in comments about the validity of the statement “That is four degrees below the freezing point of CO2 and would cause dry (CO2) ice to freeze directly out of the air.”
On one hand we have an argument from several commenters that says that the temperatures, pressures, and phase diagrams only apply to a pure state of CO2, such as in the manufacture of dry ice.
“Certainly, at least some of the CO2 in the atmosphere at the poles does freeze out (of the air) during the winter.”
So there appears to be a debate. If it turns out the statement is wrong, and some empirical proof can be presented, I’ll retract and/or amend the article. There appears to be a wide interest in this question, so I’m not opposed to find the true answer, even if it means the statement is entirely wrong.
Feel free to post in comments, but leave the snark and ad hom out of it. I’m more interested in settling the question.
I’ve also changed the title to be more reflective of the question before us now. – Anthony
By Steven Goddard
The south pole of Mars (seen below) similarly has an eight metre thick layer of dry (CO2) ice on top of the H2O ice.
Mars, too, appears to be enjoying more mild and balmy temperatures. In 2005 data from NASA’s Mars Global Surveyor and Odyssey missions revealed that the carbon dioxide “ice caps” near Mars’s south pole had been diminishing for three summers in a row. Habibullo Abdussamatov, head of space research at St. Petersburg’s Pulkovo Astronomical Observatory in Russia, says the Mars data is evidence that the current global warming on Earth is being caused by changes in the sun. “The long-term increase in solar irradiance is heating both Earth and Mars,” he said.
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More embarrassingly bad non-science by Goddard in support of the unsupportable rubbish he posted in the original article. A blog that claims to be the ‘best science blog’ should post an update to point out that it’s complete nonsense.
Steven Goddard (06:13:12) :
We have a number of posters here boldly proving that according to their misinterpretation of how phase diagrams work, polar ice caps can’t exist on earth. Look at the phase diagram for water.
http://www.lsbu.ac.uk/water/phase.html
Water vapor partial pressure near the poles is close to zero during the winter. Using the brilliant interpretation of Phil et al, the freezing point of water in Antarctica and the Arctic would be close to -70C, and there could be no ice.
You have a complete misunderstanding of a phase diagram (which refers to the pure substance). You’re describing the ‘frost point’ which under the conditions prevailing in the Antarctic winter is frequently as low as -79ºC. In fact humidity is measured in the Antarctic by measuring the frost point.
http://adsabs.harvard.edu/abs/2008IJT….29.1578C
The formation of frost is a direct deposition of ice from the vapor phase (the opposite of sublimation) and will occur at vapor pressures below the triple point of water (on the phase diagram 4.58 torr/0.61 kPa, 0.0098ºC), as long as the T, P conditions are to the left of the sublimation line.
The reason why water freezes at 273C is because of the atmospheric pressure of 1KPa, not because of the partial pressure of water – which is much lower, and varies hugely from the poles to the tropics.
More nonsense, for a start the atmospheric pressure is ~100 kPa not 1kPa (which is slightly above the triple point of water). Freezing is the process of transition between the liquid and solid states of water and can only exist at vapor pressures in excess of the triple point. On the phase diagram of water the boundary between the solid and liquid phases is approximately constant at 273K (not 273ºC!) note that in contrast the sublimation line (below the triple point) has a very strong dependence on vapor pressure.
The freezing point of water (and CO2) is fixed by the atmospheric pressure – not the partial pressure. Likewise, the boiling point of water is fixed by the atmospheric pressure and is independent of the humidity or partial pressure of water in the air.
Where do you get this rubbish from? The normal boiling point of water is the temperature at which the equilibrium vapor pressure of water equals atmospheric pressure, by definition when boiling the partial pressure of water in the air is one atmosphere! By the way at the South Pole water boils at about 90ºC.
Does Phil also believe that water boils at room temperature on earth, due to the low partial pressure of water?
http://en.wikipedia.org/wiki/File:Water_vapor_pressure_graph.jpg
Anthony, do yourself a favor and get rid of this nonsense from the blog, it will make you a laughing stock, it would get a failing grade in a high school science class.
As usual, Phil got distracted and missed the point of the article – which is wondering whether the Martian ice caps have stopped shrinking.
Really, don’t you think in that case that a more appropriate title could have been chosen? Also discussion of the atmospheric conditions of the Martian atmosphere with respect to the CO2 phase diagram would have been more relevant rather than the nonsensical stuff about the Antarctic. The partial pressure of CO2 in the Martian atmosphere is about 7mbar which will sublime at about -125ºC which is within the range of the Martian polar temperatures (just).
REPLY: Phil, the comments fall within the site guidelines, and if I start censoring comments you don’t agree with, then we’ll have a slippery slope. The comments/discussion is not part of the original article, so I don’t see any reason to delete the article. – Anthony
Bin there and done that……We had this discussion ages ago; and I was one of the proponents of CO2 freezing out of the atmosphere at Vostok.
_113 F is mega global warming at Vostok Station, where the temperature can get down to -90 C (-130 F).
And I believe it was Phil back then who disabused me of my silliness.
Even at -90 C the vapor pressure of CO2 is way above 385 ppm of earth’s atmospheric abundance.
And I have the phase diagram of CO2 right under my nose, thanks to Phil’s tuition.
Man; the thrill one gets when you finally understand some of this stuff and can yell Eureka ! I got it, how could it ever have been so hard to understand.
So Nyet ! on the Gopher getter ice at Vostok; we are cleansed of that science pestilence once and for all.
Thanks Phil; dunno how to thank you for the insight; whatta dummy I am at times.
I wouldn’t want to be David R Cooke; at the Argonne labs; maybe tomorrow, his boss is gonna walk up to him and say; David you Ar gone from this place. We’re hiring Phil in your stead.
George
RoyFOMR (03:45:20) :
“BBC beginning to blow cold on global warming?”
“No amount of “it’s even worse than we thought” headlines will convince a sceptical (sic) public if the words don’t fit with the evidence of their own eyes. 1998 remains the warmest year on record, and since then there has been no discernable (sic) upward trend. ”
“…it’s hard to see how a computer model with so much potential error in its starting conditions can accurately extrapolate what the climate will be doing in 100 years.”
However their editorial/spelling skills remain dodgy.
Steven Goddard (06:13:12) :
No, water freezes around 0C. Under polar conditions the WV partial pressure represents a dewpoint (frostpoint, actually) that is warmer than the ground temperature, then frost will grow on the ice cap. If it is cold, the ice cap will evaporate. At those temperatures, it will be a slow process.
273K…. The partial pressure of water refers to vapor pressure, i.e. gas. The temperature of freezing water changes little from pole to pole or valley to mountaintop, but frost and dew formation varies hugely. The freezing point of water is not germane to this discussion.
If you’re trying to compare water and CO2, then let’s leave the liquid phase out of the discussion. Partial pressure and temperature controls frost formation and sublimation.
The title of this article is “Natural Carbon Sequestration In Antarctica.” In my estimation, that is a poor choice of words for an article about Mars. You’ve written some good articles here and elsewhere, this is not one of them.
Is there any legitimacy in this?
http://wxmaps.org/pix/temp11.html
http://wxmaps.org/pix/temp2.html
They seem to be forecasting a heatwave across all of South Asia into Europe and most of Northern North America, but it seems strange that the latest UAH readings (using channel 5 like Roy Spencer), isn’t already seeing a sharp rise because of this?
Maybe the actual temperatures are falling short, it’s supposed to get to only 81 today here in Wichita for example, but it’s cloudy and the high so far is only 71 and rain is on the way.
On the old thread I posted a line to a CO2 phase diagram that goes down to -135C. One that was posted here is prettier but only goes down to -100C.
Phil,
The boiling point of water is independent of the humidity of the atmosphere, just as the freezing point of water is. The boiling point of water at the South Pole is depressed because of altitude (atmospheric pressure.) Why are you spreading rubbish? Ice gets thicker every year in Antarctica, despite the extremely low vapor pressure of water.
2-D Phase diagrams refer to atmospheric or ambient pressure, not vapor pressure or partial pressure. Why don’t you censor yourself instead of spreading nonsense?
Oops – it looks like Phil was first with that phase diagram in a still earlier thread, see
http://wattsupwiththat.com/2009/01/30/co2-temperatures-and-ice-ages/#comment-80219
“”” Philip Mulholland (00:24:07) :
-113F is -80.5C by my reckoning. The 1 metre air sensor at Dome A has been testing -70C this week in mixed air (no vertical gradient) with bounces up to a balmy -65C (9th June @ur momisugly 1m) when the wind stops. For the meteorologically interested, notice that the temperature gradient in still air, between the 1m & 2m sensors, can be as much as 10C per metre. Now that’s what I call a temperture inversion 🙂
The ice surface of Antarctica at this elevation (4084m or 13,400 feet) is the thermal radiator of planet Earth, heat is haemorrhaging to space, as it does every austral winter. “””
Let me see if I understand this Philip. You say the 1m and the 2m sensors are 10 deg C different. Man I tried my utmost to guess which one was colder and which one was hotter; and I couldn’t get better than 50:50 odds. Nor could I discern the surface ise temperature whcih you say is cooling the planet.
But I’m going to take a wild guess and say the temperature is perhaps -70 C(203.15 K) . I know it can get as low as -90 C (-130F, 183.15 K).
Assuming the global mean is 288K, then the Vostok ice would be only 70.5% of the global mean temperature, so its maximum black body emittance would be only 1/4 of what it is at the global mean temperature, and the Wien displacement of the IR spectrum peak would move it to about 14.3 microns, as compared to 10.1 for the 288 K mean temperature.
So other than spectral emissivity differences, just how would the Vostok ice qualify as the champion of global cooling when it gets down to -90C, that is only 63.5% of the mean so the emittance is now 6.13 times lower than at the mean earth temperature.
No Philip, If I wanted to watch the planet really cooling; I would go to the hottest North African or Arabian deserts where the ground temperatures can get hotter than +60C, and then the radiant emittance can be twice as high as the gl0bal mean or over 12 times the puny effort of Vostok Station.
You need to rethink that cooling strategy Philip; the polar regions are total pikers when it comes to doing their fair share for global cooling.
George
@Indiana Bones (10:24:31). In England, English is spelled differently than it is in Indiana. The first B in BBC stands for British. I hope this helps.
Phil,
Do you think the freezing or boiling points of water are different in the tropics than at the North Pole? Do you think that water boils at a different temperature on a humid day?
Just for reference, here is a phase diagram for CO2:
http://www.chemicalogic.com/download/co2_phase_diagram.pdf
and here is the material safety data sheet:
http://avogadro.chem.iastate.edu/MSDS/carbon_dioxide_solid.htm
And here from Praxair, a company that produces/handles/distributes a lot of CO2 they have specs. Note the freezing point at 1 atmosphere.
http://www.praxair.com/praxair.nsf/AllContent/02F1140D12AE73D785256AFC0038F75D?OpenDocument&URLMenuBranch=E6F680F2E1D730318525706D0082318E
Ric,
You are correct. The Antarctic Ice cap has disappeared because of the low humidity in Antarctica. The Vostok cores are faked and Mars has no dry ice at it’s southern pole, because of the very thin atmosphere.
What was I thinking of?
Much as I love this site, I think this type of posting feeds the fire at other blogs that make the claim that WUWT is unscientific or posts poorly substantiated claims.
As has been aptly described above, CO2 will not sublimate at the temperatures described at normal air pressures. This should not have been posted as a topic.
Thanks
Ed
Phil. Your most recent comment has been deleted, feel free to resubmit it per instructions below.
If you can show why CO2 won’t change to a solid phase at -113F, and cite references, all without making jabs and insinuations, you are welcome to resubmit your comment. – Anthony
Here is an interesting reference from WGN Meteorologist Tom Skilling’s blog:
http://weblogs.wgntv.com/chicago-weather/tom-skilling-blog/2008/10/can-carbon-dioxide-become-snow.html
“Meteorologist David Cook in the Climate Research Section at Argonne National Laboratory in DuPage County says, ”
So is the Argonne National Lab Scientist wrong?
Steven Goddard (10:42:14) :
Phil,
The boiling point of water is independent of the humidity of the atmosphere, just as the freezing point of water is. The boiling point of water at the South Pole is depressed because of altitude (atmospheric pressure.) Why are you spreading rubbish? Ice gets thicker every year in Antarctica, despite the extremely low vapor pressure of water.
2-D Phase diagrams refer to atmospheric or ambient pressure, not vapor pressure or partial pressure. [snip]
I give up with you, you continue to spout this total nonsense apparently not realising how absurd it makes you look. I suggest you follow the advice of someone earlier in this thread and read up on the subject in an introductory Physical Chemistry or Chem. Eng. text because you don’t know what you’re talking about and it’s not worth my time to educate you further. As I said before phase diagrams are for the pure substance.
Phase diagrams are for pure substances and assume ideal gas behavior, neither of which are applicable to earth’s atmosphere at very low temperatures.
“When the actual partial pressure of a gas is lower than the equilbirium pressure, p/p0 <1, and thus the spontaneous transformation is sublimation. If the pressure is higher than p0, deposition is the spontaneous one. Any other possibility would violate the second principle of thermodynamics. "
From
"Chemical thermodynamics"
by I Prigogine (Author), R. Defay (Author), D. H. Everett (Translator)
Longmans, Green (1954)
In our case, p0=1 atm so it think it's settled. Unless we don't thrust a Nobel Prize in chemistry (for thermodynamics).
“”” Steven Goddard (10:42:14) :
Phil,
The boiling point of water is independent of the humidity of the atmosphere, just as the freezing point of water is. The boiling point of water at the South Pole is depressed because of altitude (atmospheric pressure.) Why are you spreading rubbish? Ice gets thicker every year in Antarctica, despite the extremely low vapor pressure of water.
2-D Phase diagrams refer to atmospheric or ambient pressure, not vapor pressure or partial pressure. Why don’t you censor yourself instead of spreading nonsense? “””
Imagine a stiff solid container with a moveable plunger; a cylinder if you will.
So we fill the cylinder up with water occupying all the space; so there is no atmospheric gas at all in the cylinder.
Now we can apply pressure from negative to positive to the water. Water vapor will escape if we pull the plunger away from the water (or try to), and any small space will fill with water vapor at whatever the saturation vapor pressure is at whatever the water temperature is.
Now if we heat the container and its contents, the vapor pressure will rise. if we heated it to 100 deg C, the vapor pressure would reach 760 mm of Hg pressure which is the normal atmospheric pressure. But so long as we apply more than that presure with the piston; the water will not boil. If we lowered the pressure on the piston, the water would boil before it got to 760 mm or 100 deg C.
The boiling point is simply the temperature at which the saturated vapor pressure becomes equal to the ambient pressure; whatever that pressure is.
Water boils at Vostok station at 90 C because it is 14,000 or so feet high, so the ambient pressure is lower.
The thing that is different about boiling is that since the saturation vapor pressure is equal to the ambient pressure, then bubbles of saturated vapor can form inside the bulk of the liquid; so the evaporation is no longer constrained to the open surface, like ordinary evaporation is.
Actually in order for the vapor bubbles to form, the internal pressure has to exceeed ambient by 2T/r, where T is the surface tension of water, and r is the radius of the bubble. Since r must presumably start at zero, the required internal overpressure would be infinite, which is why very clean water can sauperheat and fail to boil at the appropriate temperature. So dust particles or even cosmic rays can start superheated water boiling, by providing a non zero starting radius for the bubble (neve nuke clean water to make coffee; always put the coffee in first to allow finite radius bubbles to form, should the temperature get to boiling.)
I found some Vostok temperature record data on their website; and in addition to the daily temperature plots they also plotted the dew point, which mostly was always below the ambient temperature; so the humidity was less than 100% most of the time.
Under those conditions the equilibrium would normally move towards evaporation; or in this case sublimation since we are way below the triple point for water.
I believe that temperate or tropical ocean evaporation brings moist air over Antarctica all the time, which greatly exceeds the amount of water the colder air is capable of holding, and it is that moisture which provides the constant thickening of the Antarctic ice sheets; whcih continue to grow.
But when all that excess moisture deposits out as new ice; the humidity can still drop below 100% so the dew pint falls below ambient.
The dry ice on Mars is there because the bulk of the atmospheric pressure is CO2, and the polar temperatures are way colder than the triple point.
At 1atm (760 mm Hg) I have -78.5 C for the sublimation point; at 76 mm it is about -100, and at 7.6 mm it is about -120 C. Not sure what Martian atmospheric pressure is but if we used parachutes to slow stuff for landing, I suspect it is more than 1% of earth pressure.
Phil you may very well be correct but I find myself hoping that you’re wrong simply because you’ve been a right jerk about it from start to finish.
Obviously my hope has no impact on reality but I’m pointing this out because I think you needed a correction as well. Specifically that even if you are completely correct in this discussion you are still wrong for how you’ve gone about making your points and being rude to the man.
You’re calling him out over a mistake and trying to embarrass him rather than simply make the correction for correctness sake. What part of the scientific process states that you should ridicule a person who gets something wrong?
REPLY: I agree. We don’t have to be rude, condescending, or taunting to get points across. “Phil.” works for a major university, his way of dealing with people here make me wonder how he might treat students that are trying to learn. – Anthony
wattsupwiththat (11:13:32) :
Phil. Your most recent comment has been deleted, feel free to resubmit it per instructions below.
If you can show why CO2 won’t change to a solid phase at -113F, and cite references, all without making jabs and insinuations, you are welcome to resubmit your comment. – Anthony
I already have done so with reference to the phase diagram which I notice you have reposted above.
And here from Praxair, a company that produces/handles/distributes a lot of CO2 they have specs. Note the freezing point at 1 atmosphere.
Good luck finding it, CO2 doesn’t have a freezing point at a pressure below 5.11 atm! A block of solid CO2 at atmospheric pressure does have a sublimation point of -78ºC at which temperature the vapor pressure of CO2 in equilibrium with the surface is one atmosphere. Because of the reduced pressure a block of CO2 at the South Pole will have a sublimation point of approx. -83ºC. As stated above deposition from the atmosphere will require a temperature of approx -140ºC.
wattsupwiththat (11:29:55) :
So is the Argonne National Lab Scientist wrong?
Yes!
This is basic physical chemistry and shouldn’t be a matter for discussion.
REPLY: Maybe so, but for us that don’t deal with the subject every day, could you provide a link or citation for “CO2 doesn’t have a freezing point at a pressure below 5.11 atm”. I’ve looked for references about CO2 freezing point and pressure, and so far have found none. I’ll be away for a bit, so take your time. – Anthony
“”” wattsupwiththat (11:13:32) :
If you can show why CO2 won’t change to a solid phase at -113F, and cite references, all without making jabs and insinuations, you are welcome to resubmit your comment. – Anthony “””
Anthony, according to the CO2 phase diagram, the equilibrium vapor pressure of CO2 over dry ice at -113 deg C is a little bit more than 0.01 of atmospheric pressure; I estimate about 0.012 atm, or about 9 mm Hg pressure.
Assuming CO2 is 385 ppm of the atmosphere (by volume), and CO2 molecular weight is 44 versus about 28.8 for the atmosphere, then that is about 588 ppm by weight or about 0.447 mm Hg partial pressure of CO2 at sea level.
Not sure what the atmospheric pressure is at Vostok; but that can only make the CO2 partial pressure even lower than 0.447 mm Hg, which is less than 1/1000 of atmospheric pressure, which is the saturated vapor pressure of CO2 at about -135 deg C.
So I have to argue that there can’t be any amount of permanent CO2 ice at Vostok Station even thoguh I once thought thatw as possible.
Which does not mean that Mars cannot have dry ice at the poles; the conditions do allow for that there; but not here.
George
When the air temperature is below 0˚C, all the water does not immediately freeze out. The question is, how cold does it have to be for ~300ppm of CO2 to condense onto a cold surface.
C Shannon (12:06:16) :
Phil you may very well be correct but I find myself hoping that you’re wrong simply because you’ve been a right jerk about it from start to finish.
Obviously my hope has no impact on reality but I’m pointing this out because I think you needed a correction as well. Specifically that even if you are completely correct in this discussion you are still wrong for how you’ve gone about making your points and being rude to the man.
You’re calling him out over a mistake and trying to embarrass him rather than simply make the correction for correctness sake. What part of the scientific process states that you should ridicule a person who gets something wrong?
I called him out over the mistake and referenced the phase diagram to show him his mistake, he then posted a load of rubbish and very aggressively told me I was wrong, after that he deserves everything he gets. Right now he’s embarrassing himself with every post he makes without any help from me.
REPLY: I agree. We don’t have to be rude, condescending, or taunting to get points across. “Phil.” works for a major university, his way of dealing with people here make me wonder how he might treat students that are trying to learn. – Anthony
I have no problem with students who’re willing to learn in fact I get high evaluation scores and my class is always oversubscribed. However equating Goddard with a student who’s willing to learn is not accurate, he pontificates about science he doesn’t understand and when he’s called up on it lashes out with more errors as you can see above. When this topic last came up here with George we had a civilized discussion and George thanked me for explaining it to him.
REPLY: Well to that I’d say Phil, take this old adage to heart: ” You can catch more flies with honey than you can with vinegar”. Mostly, your persona here has been vinegar. Your first comment to Steve was vinegar. Try another tact, stop labeling people, and you might be more successful at education online. – Anthony