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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If my previous comments are not clear, the point is that even frozen materials have a surface vapor pressure, and that vapor pressure is strongly temperature dependent. CO2 vapor pressure vs temperature can be found in a handbook such as the handbook of Physics and Chemistry. Above a certain temperature, the condensation is gas to liquid (unless the pressure is too low for a liquid state), but below a critical temperature the condensation is gas to solid. Squirting liquid CO2 (which was under pressure) into a low pressure surrounding causes some to immediately boil off and freeze the rest due to heat of vaporization, but the dry ice will all evaporate if left in the lower pressure. It just takes a while to get the heat of sublimation. This is not a steady state situation, and does not apply to the present discussion.
Anthony, it may be staring me in the face, but I don’t see a direct email address for you. Email me at the address I’m using for this post so I can email you the photos and results.
REPLY: sailing through the ether as we speak.
Sandy, the rated capacity of the freezer is 26 cu ft, but it is nearly completely filled with sample boxes. However, the door is normally opened several times a day, to add or retrieve samples, so there is ample opportunity for CO2 loading over the period between defrosts (usually at least one year apart). There is also a vacuum release vent that admits a small amount of air whenever the door is closed (ambient air drawn into the freezer when it is opened cools, resulting in pressure drop and partial vacuum that seals the door against further opening if the vent is blocked). The vent accumulates water ice; I lack the instruments to determine if the snow around the vent also contains CO2.
Based on the arguments presented here, the two postulated outcomes are,
1) significant loss of mass, as the sublimation rate exceeds the deposition rate
2) no change, or negligible gain in mass.
(I suspect that any gain in mass will evaporate on the short walk from the freezer to the balance.)
It’s admittedly an imperfect experiment. But I expect the outcome will be rather obvious; the dry ice will be gone in the morning. We’ll see.
Well Anthony thank you for your personal implication in this stuff, and for the courage to recognize faults when you see them, even on your own blog :0)
I hope this will settle the discussion, because it looks like these comments could go on and on for ever. IMHO this is because there is no “authority” on a blog. Even if I (or you or Phil or any other) says he’s a “specialist” on a topic, the absence of direct dialogue and possibility to verify such assertions provoke never-ending discussions.
In the interest of accuracy do you have any way to insulate/shield from heat gain during that walk to the balance? A pre-cooled container perhaps for transport? Or move the balance to the refrigerator?
Interesting discussion.
Unfortunately Steven Goddard got this one completely wrong.
The Argonne scientist got it wrong too.
Phil is correct in this case.
CO2 phase diagram is very simple in comparison to water phase diagram. Please study it. It is all in that diagram.
The sublimation temperature of CO2 at 1 ATM is -78.5 C. At this temperature the vapor pressure of the solid CO2 is equal to the total pressure of the gas phase in contact with it which is 1 ATM. If the atmosphere would have 100% CO2, the pressure is 1 ATM and the temperature is -78.5 C, then an equal amount of CO2 is deposited as solid as is sublimed as gas. Things would be in balance. Again, if the atmosphere is 100% CO2, pressure is 1 ATM and the temperature is below -78.5 C, then more CO2 is deposited than sublimed (you are on the left side of the “solid-gas” line in the solid area in the phase diagram).
When the pressure of CO2 goes down, the sublimation temperature goes down too. That is the “solid-gas” line in the phase diagram. With 385 ppm CO2 concentration the partial pressure of CO2 is so low that the temperatures needed for deposition to take place do not naturally occur on this planet.
There is no freezing of CO2 below 5.11 ATM because liquid CO2 does not exist below 5.11 ATM. CO2 triple point is -56.6 C and 5.11 ATM. Below 5.11 ATM only solid and gas phases exist.
There is no need to make any experiments about this (unless you want to learn thermodynamics). This has been experimented years ago, that’s why we have the accurate CO2 phase diagram available.
Jari has it exactly right. The temperature at which the vapor pressure of frozen CO2 exceeds the level in our atmosphere is -140 C ( -220 F)
Steve goddard,
Atmospheric pressure has no effect on the vapor pressure of water or ice that has no heat being added, only the water or ice temperature. Boiling is a different phenomena in that it occurs when the vapor pressure reaches the local total pressure. Since the vapor pressure above water or ice cannot exceed the local total pressure, the vaporization removes heat by heat of vaporization or sublimation to cool the surface until the vapor pressure is matched. Boiling occurs when continual heat is added that has to be removed, and the continual vapor forming removes the heat.
Tom (19:32:18) :
Exactly right, at least good enough for scientific work. To test Steven’s claim, you don’t even need the dry ice (except to maintain the concentration in the air in the freezer). Steven’s claim is that you can put an empty dish in the freezer and it will accumulate CO2 frost over time.
How much of an issue is water ice condensation? It’s not a problem for your proposal as long as dry ice evaporates faster than water condenses. Indeed, absence of water ice formation would suggest that both water and CO2 concentrations are too low.
Unfortunately, your result may not end the controversy. Assuming that your dry ice evaporates, critics can point out that the heat exchanger must be even colder than the contents of the freezer and that’s where CO2 condensation occurred.
I get impatient when I see >180 comments, but this has been a pretty good thread.
Question, though: has anyone actually seen any CO2 ice at the site in question?
George E. Smith (10:49:29) :
My my George, that seems to be a little bit tetchy. Not your usual tone I trust and at variance with your comment # 142915 “I always learn something from other people’s posts”
I am sorry that, unlike more skilled posters, I have to rely on words and links and not pictures to describe the temperature inversion seen at Dome A in still air.
I hope by now you have had a chance to follow the link in my second post to the Australian Antarctic Division website where my quote of the 10C gradient comes from. I also thought that the meteorological term temperature inversion was understood. Here in the UK we have ground frosts and air frosts, this distinction is not esoteric.
Maybe what I was taught in 1972 concerning the mechanism of the generation of cold deep bottom water in the modern world ocean no longer applies? Let us start at Dome A, for example, with its commonly occurring winter surface inversion generating cold air, (now that the sun is set and will not rise again at Dome A until 0605 UTC on 26th August 2009), the mixing and export of cold air down slope off the icecap forming the Katabatic winds that sweep down to the Weddell Sea . The generation of sea ice and the attendant production of Weddell Deep Water , the thermohaline circulation mechanism and its role in bottom water oxygenation and the consequent lack of sapropel deposits in modern ocean basins compared to the Cretaceous.
Then we must consider the Tethys Ocean with its extensive epeiric seas and their attendant carbonate ramps generating warm dense saline bottom water and the lack of equivalent modern mid-latitude epeiric seas. The fact that exported warm saline Mediterranean bottom water , for example, is less dense than and floats above the cold saline polar bottom water of the bathyal Atlantic, giving us a glimpse of how the ocean circulation mechanism worked during the Cretaceous, when the world was warm.
The modern world is a cold world George. I am still confident that our cold ocean world is due to the Antarctic icecap exporting heat to space and not the diurnal cooling of mid-latitude deserts.
Perhaps an indirect method of sequestering CO2 in the Antarctic: There is a differential solubility in water of the component gases in air that results in the preferential concentration of CO2 and, as is well known, it increases with declining temperature:
http://www.engineeringtoolbox.com/gases-solubility-water-d_1148.html
Some solubilities in g/Kg at 0C, 10C and 20C
Ar: 0.1g; 0.08g; 0.06g
CH4: 0.28g; 0.22g; 0.14
CO2: 3.4g, 2.5g 1.7g
N2: 0.03g; 0.025g;0.02
O2: 0.07g; 0.06g; 0.04g
Look at the enormous solubility of CO2 relative to the other atmospheric gases. “Air” dissolved in water would therefore have a much higher concentration of CO2 to outgas – say if warm water circulated down to the Antarctic, thereby increasing the local atmospheric concentration of CO2. The CO2 could get quite high if a sub sea volcano were to feed in CO2. A breeze over the continent from the sea…… Recall mention in another post of dissolved CO2 in an East African Lake outgassing and killing a number of people. (OT; I’ve mentioned in another post the possibility of a terrible accident if we start sequestering CO2 in underground reservoirs….potential for breach…faults, seepage into a valley…). Perhaps some physical chemists may be able to carry this discussion further.
@ur momisugly Ric Werme (04:46:22):
I can only do the best with what I have. The simplest experiment would be to simply scoop out the frost from inside the freezer to see whether it contains more than 300ppm of CO2, but I don’t have the equipment to do that. I would not be surprised that CO2 could condense on a sufficiently cold surface, even at 1 ATM on Earth, but that temperature seems to be much lower (-140C I think). I could draw off some liquid nitrogen (-196C) from our dewar and collect the frost that accumulates on the braided steel transfer hose, but again, I don’t have the means to analyze it.
It seems to be a prerequisite for the argument that CO2 would condense at Vostock that pre-formed dry ice at that temperature should not sublimate appreciably. I think I can test that.
Moderator:
Last night’s comment about too steep a thermal gradient
really was from me — but from another machine. The
comment seems to have been filtered out. It is still
pertinent, so feel free to include it.
REPLY:AFAIK gone, but I don’t moderate overnight, sorry, feel free to resubmit- Anthony
can I add my two penneth to this debate, especially as someone who constantly works with CO2 in the lab and at low vapour pressures!
The vapour pressure of CO2 in the Earth’s atmosphere is about 40Pa. For CO2 to begin to freeze, resulting in a solid, at this vapour pressure would require temperatures below about -140 degrees C.
The statement at the top of this article by the scientist from the Argonne National Laboratory is simply wrong.
George E. Smith (10:13:22) :
I missed that yesterday. Oh, the Argony.
I sent mail to Dr. Cook and the Ask-a-scientist site this morning and invited him to post here or give me something to post on his behalf.
REPLY: “Argony” is the inert form of “Irony”, it does not react to air, hot or cold. 😉 – Anthony
I just heard from Dr. Cook, I think this warrants an update to the top of the page. It looks like Dr. Cook isn’t considering the vapor pressure of CO2 in well mixed atmosphere, since the vapor pressure of CO2 requires the -140 F temperature in the estimates above.
Ric,
You are correct. In my attempts at being simplistic I made a mistake in my answer to “Freezing CO2” on the Ask-A-Scientist page. -57 C is the boiling point of CO2. The freezing point of CO2 at atmospheric pressure is -78.5 C (-109.3 F). If the temperature reaches -113 F at Vostok, Antarctica, some carbon dioxide might freeze out of the air, assuming that the carbon dioxide vapor pressure drops to its saturation vapor pressure.
The vapor pressure must reach the saturation vapor pressure for dew or frost to form. This happens at the dew point or frost point temperature, which is dependent on atmospheric pressure and the absolute amount of vapor in the air. As atmospheric temperature increases, the dew/frost point temperature increases. As atmospheric pressure increases, the vapor pressure increases. At very low temperatures, the dew/frost point temperature is very low.
When the temperature of the surface (whether grass or a car window) is below freezing, frost will usually form instead of dew, although water can be super-cooled and not produce dew, fog, or clouds in some cases. Surfaces on the Earth cool off sooner than the air, so dew/frost will normally form on them before fog (water or ice) forms in the air.
The temperature being at “freezing” or below does not imply that frost will form on surfaces or in the air. The vapor pressure must be high enough (saturation vapor pressure) and the temperature low enough (the frost point temperature) for frost to form.
REPLY: Thanks Ric, I’m going to make a summary post, it will be included there. – Anthony
Absolutely great debate ! A fine example of what has been missing in the climate debate. An open and real time exchange of ideas that reflect primary understandings, but does not exclude experiences or new thinking and data.
The great thing about science is that theory has to be proved by experiment and therefore before anyone says that Steve’s claim of –
“According to Weather Underground, Vostok, Antarctica is forecast to reach -113F on Friday. That is four degrees below the freezing point of CO2 and would cause dry (CO2) ice to freeze directly out of the air.
is wrong I’d like to point out that
1) It ain’t Friday
2) When it is Friday it’s going to be hard to disprove unless you are actually on site.
So in theory you may have your own conclusion but in actuality the actual proof one way or another is unlikely to ever be published.
Not that I condone tabloid headlines of course.
Oh, and what is this F stuff ? We don’t do polar extent in square furlongs anymore so lets drop the silly old fashioned temp scales.
C or K please, preferably C.
Regards
Andy
The great thing about science is that theory has to be proved by experiment and therefore before anyone says that Steve’s claim of –
“According to Weather Underground, Vostok, Antarctica is forecast to reach -113F on Friday. That is four degrees below the freezing point of CO2 and would cause dry (CO2) ice to freeze directly out of the air.
is wrong I’d like to point out that
1) It ain’t Friday
2) When it is Friday it’s going to be hard to disprove unless you are actually on site.
So in theory you may have your own conclusion but in actuality the actual proof one way or another is unlikely to ever be published.
Not that I condone tabloid headlines of course.
Oh, and what is this F stuff ? We don’t do polar extent in square furlongs anymore so lets drop the silly old fashioned temp scales.
C or K please, preferably C.
Regards
Andy
Since you guys don’t believe that we can accurately measure temperatures on Earth, why would you think that we can accurately measure them on Mars?
All this chatter about phase diagrams but I didn’t see anyone mention the 3D – phase diagram.
http://biomodel.uah.es/Jmol/plots/phase-diagrams/
“”” Philip Mulholland (05:00:15) :
George E. Smith (10:49:29) :
My my George, that seems to be a little bit tetchy. Not your usual tone I trust and at variance with your comment # 142915 “I always learn something from other people’s posts” “””
Sorry Philip; it wasn’t meant to come out that way. And I posted before I even looked at your link to A-dome. Now I have a nice pretty picture of that week or so of data, ands a new favorite’s link on my browser.
If you are an A-Dome denizen, expect to see me in the area; I collect cold places to learn about; so thanks for another one.
Your post did raise one thing I had a problem with. The exact link you gave was a graph that did not have a plot for the sub-surface 10 metre data. It was listed on the legend but with no color bar, and of course no graph.
So Unfortunately I was not able to see the anomaly you raised; so sorry can’t even guess; but I do like the data that was there anyway; and I am sure I can find a graph that has the -10 metre line.
The huge air height gradient you alluded two is pretty spectacular.
But anyway; my apologies for being rude; that isn’t my usual me.
Do they really think Dome-A is going to pan out colder than Vostok; and what do they figure the ice thickness is there. I presume that some Aussies plan bore some holes there. But yes that 1m, 2m, 4m differential is awesome.
The reason I was originally intrigued by the possibility of dry ice down there was, I imagined the atmosphere sans any kind of GHGs to speak off and how close to being in outer space that would be; in terms of falling off the bottom of the temperature scale. I guess that’s not to be. I did like the “dewpoint” graphs from Vostok; and the idea of a CO2 “dewpoint” is even weirder; you can brek your knuckles on some of that “dew”.
Humble George
One other thing Philip.
I have on several occasions posed the question: Why on earth do they have all that ice down in Antarctica and also up in the Arctic ocean where it melts back every year. It is important because when it melts leaving ocean that absorbs sunlight; we lose albedo, and gain near black body absorption.
Well we don’t have tons of ice all over the place in Silicon Valley; yet we have plenty of water around, in the Bay, and off the coast. I think the answer lies in all that sunshine that California is famous for .
It appears that the Arctic, and the Antarctic must be severely deprived of sunlight; and I’ll bet that is why it is so bloody cold in those places. It is NOT cold there because of all of that ice and snow; and your Dome_A graphs prove that; at the coldest times the air is even colder than the ice; so the ice certainly isn’t making things cold; it is there ONLY because it is cold; and it is cold ONLY because THERE’S NOT MUCH SUNLIGHT.
And of course since there is not much sunlight anyway; it matters very little that the arctic ice melts and turns into a black body absorber; there ain’t much of anything to absorb anyway. So the effect of polar albedo is pretty minor in the overall scheme of things.
Climatology seems to get the cart before the horse all the time.
The surface Temperature changes CAUSE atmospheric CO2 changes; NOT the other way round. The polar regions have a lot of ice because it is lacking sunlight and therefore cold; NOT the other way round. You get wispy high clouds at night BECAUSE it is warm and balmy; and no clouds at night BECAUSE it is cold and dry; NOT the other way round.
AlGore gets the correlation; he just doesn’t get the causality.
End of Rant.
Anthony, as I mentioned above:
Perhaps an indirect method of sequestering CO2 in the Antarctic: There is a differential solubility in water of the component gases in air that results in the preferential concentration of CO2 and, as is well known, it increases with declining temperature:
http://www.engineeringtoolbox.com/gases-solubility-water-d_1148.html
I should add that, not only would the cold antarctic waters hold more CO2, in the depths of winter, but when the water is freezing, the CO2 also outgasses from the ice. This would make for a higher CO2 concentration in a layer that might blow into the interior and freeze. What would be the result of, say 0.07% CO2 at -85 C? I think this should be at least examined in any post that is done on sequestration of CO2 rather than looking only at a steady 0.037%. Taken a step further, if atmospheric CO2 continues to rise reaching say 0.1% then some where near this amount might represent the maximum level as any additional CO2 might be sequestered in equilibrium.
REPLY: I’m not sure your analogy works well at Vostok Station. On this website they talk about the lack of CO2 in the air at Vostok Station affecting human existence there.
http://www.absoluteastronomy.com/topics/Vostok_Station
– A partial pressure of gases that is different from that which most humans are used to.
– A lack of carbon dioxide in the air, which leads to irregularities in a person’s breathing mechanism.
– Anthony