[Bored chemist]

"The remaining 0.1 is air, hence 10% of an ice berg is above water. "
Nope.

[Pete Ridley (OP)]

Hi Bored Chemist, come on, help out a poor layman with more than simply "nope".

How about using you superior knowledge to expand on your “Nope” something along these lines

.. water is one of the few substances that is slightly denser as a liquid than as a solid. This is why ice cubes float in water. .. Most icebergs actually contain a lot of air. Far from being the solid blocks of ice many people imagine, icebergs are riddled with billions of tiny, trapped air bubbles, giving the huge bergs their white appearance. .. icebergs are made from fresh water. Because of the dissolved salts in ocean water, it is denser than freshwater, adding bouyancy to the icebergs

(http://www.lifeslittlemysteries.com/why-do-icebergs-float-0261/).
Perhaps you’d like to put some figures to the contribution each of those makes towards lifting 10% of an ice berg out of the water. I don’t want to spend my time researching that as it is not really significant with regard to my main question here, but since you can’t respond to that one (too hard for you I guess) perhaps you can help Wiybit out a little. How’s about having a go at that question he has about Fickian diffusion?

Best regards, Pete Ridley

[rosy]

Oh good grief!

Density of freshwater ice (such as that made from snow): 0.92 (without taking into account any airbubbles)
Density of surface seawater: 1.02-1.03
Expected proportion of iceberg above water level based on these figures: 1.02/0.92 = 1.11

So without considering the effect of the small air bubbles present in the ice, about 10-11 % of the iceberg is expected to float above the water. Elementary arithmetic, and a little bit of looking up numbers (I used wikipedia, other data sources are available).

Do you think a lump of ice composed of 10 % air bubbles by volume would be strong enough to withstand being pulled out of the ground with an ice-core drill? Seems rather unlikely to me. Ice is brittle stuff.

[Jolly- Joliver]

You ask “ .. how can you even know the starting point of a molecule? I sounds like a lot of guess work to me .. ” and I can’t argue with that. The experts call it probabilities.

Most likly with a certain range, it's "slightly" better than guess work.

Hi Wiybit, regarding your

15/04/2011 16:21:39 ..  I think you mean it's a multi-layered process.

I see the size-dependent fractionation and close-off processes as being “multi-layered” in space and time.

I see the complication your refereing to, but at the same time are not all psyical processes, both temperal and spacial?

Your

… Ice is a solid isn't it, I kinda think it's like as ice forms and compacts the gases are squezzed out, and if as you are suggesting gases can move through smaller, gaps then I suppose more would be squezzed out.

is getting there. Put simply, snow is also ice but, as I said before, has a density of as low as 0.2 that of water. As it is compacted it approaches a density of about 0.9 that of water. The remaining 0.1 is air, hence 10% of an ice berg is above water.

Well if those figures are correct and 0.1 of 1 is air then 10% is air in the form of pockets sandwiched between the ice. But I think there might be a mix up, at 0.2 what is the air make of of a flake? 

I mean your saying that as ice compacts it gains a density of 0.9 compared to 1 of water, but why is the 0.1 difference made up by air? Could it not be 0.9 and 0,2 air? Or are you saying that as a liquid cannot be condensed, proportionally one for one, the water to ice is 0.9 ice and so 0.1 gas to 1 water centermeter cubed(for example)?

Regarding kinetic diameter you asked

.. but why do they ignore it? They either are ignorant of it or some some reason feel it has no bearing, or plays to insignifcant a role to be accounted for. I assume, but it sounds a bit strage for scientists to just ignore, a kinetic factor for no reason. What is the justifaction for ignoring it?

. You are repeating the question that I have been putting to the paleoclimatologists for more than a year now and The Naked Scientists three days ago in my first post above. None have answered it yet. It is worth noting that experts in the field of gas purification, such as in the energy and pollutant extraction industries use kinetic, not collision, diameter. I have made this point on numerous occasions to the “experts” and none have explained why they choose to ignore the smaller kinetic diameter of CO2 compared with N2, O2 CH4 and Ar. That’s odd, don’t you think?

Yes it is odd but atleast we get to the crux of your question.

.. what is it about Co2 that makes it so different? Personally I think much of the man made co2 we have in the atmospere is comming from CO cabon monoxide, which when realesed from burning fuels etc grabs an oxygen and so forms Co2 ..

. I’m would expect that this “ .. media-savvy group of physicians and researchers from Cambridge University .. ” (http://www.thenakedscientists.com/HTML/about-us/) called The Naked Scientists should be able to offer a valid answer to that question. I think that you may be way off-beam with your hypothesis about CO, considering that when hydro-carbon fossil fuels are burnt the main products are H2O and CO2, with CO being comparatively minor.

I possibly am but at the same time CO is released from every car, even if it is minor per individual car, it will not be for all of them.

 

.. Implies Co2 is a smaller molecule, yet surely it's bigger then 02? What missing? ..

. In this context we are talking about size in terms of volume not weight (think of a balloon).

.. could it not also be the case that the cores have trapped Co2 from the ice below them? Can we trust the findings at all really? ..

. My hyp[othesis says “Yes” to part 1 and “No” to part 2.

Regarding the difference in collision and kinetic diamter

.. Note the difference for CO2. It's .6 compared to 0, 0.2 or 0.1 with the others, why does it have such variation? ..

, again, there should be at least one of The Naked Scientists who can answer that question.

You seem to have completely missed the point of my mention of the He balloon by saying

..
Strange he is lighter than Co2, so Co2 moves more in because it's smaller fairly clear ..

. I was hoping that you’d realise that the reason the He-filled balloon collapses relatively quickly is because the balloon is a bit like those air pockets in firn – it has lots of tiny pores that are so small that He (0.26nm kinetic diameter) can escape more readily that the larger N2, O2 and Co2 molecules of the expelled air we puff into a balloon.

But then that is contradictory, if Co2 moves more readily than He, He is smaller and lighter, so why would Co2 be under a greater kinetic effect in ice than He as you have suggested?

In saying of the scientists that I mentioned

.. Maybe it's too complicated, and add too many varibles ..

you are effectively agreeing with Professor Jaworowski, who, as I’ve already told you, said “This is a highly specialized field of science. My impression is that it is a terra incognita for glaciologists”.

Finally you said of that CO2 that escapes from the air pockets and heads down the pressure gradient towards the surface

.. Yes, I meant escaped into the atmosphere. From what you have said I'm not sure if you could really say either way .. [/quote. I ’m inclined to agree with that.

(I know, I still haven’t responded on Fickian diffusion. I need more time for that one, after all, I’m only a retired engineer).

May I just say how enjoyable it is exchanging opinions with you in the spirit of improving understanding rather than scoring points or pushing a particular doctrine. It’s a great shame that on most blogs that I get involved with it ends up simply being a battle by both sides to win an argument.

Best regards, Pete Ridley

Yeah, I know that situation well.

Peace

P.S. As a last point there is the "quote" Box in the top right corner of each post a person makes.

[Geezer]

I confess I'm not much of a scientist, but I have to admit I find it interesting that anyone who is unaware of why ice cubes float in water might think they are qualified to call into question the scientific credentials of anyone else.

[Pete Ridley (OP)]

Hi rosy, thanks for applying your mathematical and “Google” talents to the question of how much air there might be in an iceberg, although you stopped before you arrived at an answer. How about developing your analysis a little further by taking into consideration the difference between the “ .. average density of seawater at the ocean surface  .. ” offered by Wikipedia (http://en.wikipedia.org/wiki/Seawater) and the actual density of seawater surrounding an iceberg. That will be much more useful in aiding our understanding of how “solid” the ice in an iceberg really is.

Your

Do you think a lump of ice composed of 10 % air bubbles by volume would be strong enough to withstand being pulled out of the ground with an ice-core drill? Seems rather unlikely to me. Ice is brittle stuff

suggests that you haven’t spent much time researching ice cores or much time trying to understand my question about “Another Hockey Stick Illusion?”. As you may not have realised, my question here relates mainly to the process of size-dependent fractionation occurring in the firn, not in the “solid” ice (although there is further fractionation there too). According to your speculative comment it should not be possible to remove ice cores from firn but I am not aware that there is a problem there. Maybe you can provide a link to evidence supporting your opinion on this.

A Google search will take you to some interesting papers, including pictures, which should clarify this for you. Yes, those cores a brittle and need very careful handling, but those ice core experts are able to extract long cores even from the much less dense firn above that solid ice. They are so clever at it

.. Using the PICO (Polar Ice Coring Office) lightweight auger, a 31 m long firn core was drilled adjacent to the cane farm at GD03. The GD03 core represents 55 years of annual snow-accumulation increments which were interpreted from the combined stratigraphic analyses of density, oxygen-isotope and visible layering. A vertical profile of density .. shown in Figure 2 ..

, (http://hyperphysics.phy-astr.gsu.edu/hbase/kinetic/henry.html Page 385 of the source document). Perhaps you should have a good look at the density graph in Fig. 2 before responding.

Hi Wiybit, I was disappointed that none of this “ .. media-savvy group of physicians and researchers from Cambridge University .. ” have tried to help you out on your

.. fickian law  .. looks to relate more to solids then gases ..

. I’d love some help on the relevant laws of diffusion too and since none of The Naked Scientists seems to be able to help I took the opportunity of chatting about that (and my question about “Another Hockey Stick Illusion?”) with Professor Andrew White who was visiting us this weekend.

Dr. White is Professor and Director, Center for High Energy Physics Research and Technology, Department of Physics, The University of Texas at Arlington and has been a Professor of Physics there for 20 years (http://www.uta.edu/physics/main/faculty/). During that time he has been involved in research at CERN so I thought that he could perhaps save me some time digging up an answer for you. As Bored chemist might say “Nope”. His response was “I’m not up on diffusion” so I had to try elsewhere. Does this help

Fick's Law: The net diffusion rate of a gas across a fluid membrane is proportional to the difference in partial pressure, proportional to the area of the membrane and inversely proportional to the thickness of the membrane. Combined with the diffusion rate determined from Graham's law, this law provides the means for calculating exchange rates of gases across membranes

(http://hyperphysics.phy-astr.gsu.edu/hbase/kinetic/henry.html)?

Geezer, I hope that you were able to spot the point I was making about Dr. White's response to my question. I’ll also mention that I discussed your

.. I find it interesting that anyone who is unaware of why ice cubes float in water might think they are qualified to call into question the scientific credentials of anyone else ..

and you’ll also find it interesting that he does not share you implied opinion. His appears to be completely opposite to yours. Why not drop him an E-mail (awhite@uta.edu) and ask him. After all unlike either of us (and many of those who support the CACC doctrine), he is a highly respected scientist.

Best regards, Pete Ridley

[Jolly- Joliver]

Hi Wiybit, I was disappointed that none of this “ .. media-savvy group of physicians and researchers from Cambridge University .. ” have tried to help you out on your

.. fickian law  .. looks to relate more to solids then gases ..

.

Seriuosly you shouldn't encourage them(if you get me). []

I’d love some help on the relevant laws of diffusion too and since none of The Naked Scientists seems to be able to help I took the opportunity of chatting about that (and my question about “Another Hockey Stick Illusion?”) with Professor Andrew White who was visiting us this weekend.

Andrew is Professor and Director, Center for High Energy Physics Research and Technology, Department of Physics, The University of Texas at Arlington and has been a Professor of Physics there for 20 years (http://www.uta.edu/physics/main/faculty/). During that time he has been involved in research at CERN so I thought that he could perhaps save me some time digging up an answer for you. As Bored chemist might say “Nope”.

Yeah BC can be slightly funny at times, but generally he's ok, when not going on about dance routines and stuff, and trying to catch you out(so he can laugh at you)  [] Completly said it light hearted jest BC so don't start.

 His response was “I’m not up on diffusion” so I had to try elsewhere. Does this help

Fick's Law: The net diffusion rate of a gas across a fluid membrane is proportional to the difference in partial pressure, proportional to the area of the membrane and inversely proportional to the thickness of the membrane. Combined with the diffusion rate determined from Graham's law, this law provides the means for calculating exchange rates of gases across membranes

(http://hyperphysics.phy-astr.gsu.edu/hbase/kinetic/henry.html)?

Thanks, I'll check it out. Yet you still haven't said what it is about Co2 that causes it to act so differently to the other elements, surely HE should move more, in ice if it's smaller and lighter?

[rosy]

suggests that you haven't spent much time researching ice cores or much time trying to understand my question about “Another Hockey Stick Illusion?”.

Wrong, I've spent no time at all researching ice cores or trying to understand your question. I'm not an expert, and I certainly don't have sufficient free time to do the necessary research, so I leave it to other people.

I'm going to be rude, now. I usually try not to be too rude online, but on this occasion I am completely out of patience, both with your approach to science and with your personal demeanour.

Moreover, I certainly would not trouble to put in all that legwork to answer a question from you, Pete, because although your initial ignorance of what causes ice to float is (just about) understandable, although surprising in someone who claims to have been taking an interest in climate change issues for some time, your apparent failure to make even a token effort to understand what's actually going on by making a few back-of-the-envelope calculations of your own leads me to believe that even if I understood, and explained, it wouldn't improve your understanding because you are more interested in a quasi-religious fight against "the climate change establishment" than in obtaining any level of personal understanding of the field in order to be able to make an intelligent contribution. This is for exactly the same reason I don't bother to argue with creationists about evolution.

Now, if anyone is actually interested (and I acknowledge this isn't rocket science...), the densities of water at different temperatures are given here:
http://www.sfu.ca/physics/ugrad/courses/teaching_resources/demoindex/fluids/fl2b/density.html
The density of pure water is, at least, 0.998 (density at 0 ^oC, density at 4 ^oC is a little higher. If the ice (at 0.92) were floating entirely on its own (pure) melt-water, it would float with 8.5 % of its volume above the water. But the water is not pure, it is mixing all the time with salt sea-water, so it might be fractionally less dense than the average surface water density (1.02-1.03), but the absolute lower limit is that 8.5 % will float above the surface, in reality it will be more, and that's entirely without considering the effects of air bubbles.

[Jolly- Joliver]

Now, if anyone is actually interested (and I acknowledge this isn't rocket science...), the densities of water at different temperatures are given here:
http://www.sfu.ca/physics/ugrad/courses/teaching_resources/demoindex/fluids/fl2b/density.html
The density of pure water is, at least, 0.998 (density at 0 ^oC, density at 4 ^oC is a little higher. If the ice (at 0.92) were floating entirely on its own (pure) melt-water, it would float with 8.5 % of its volume above the water. But the water is not pure, it is mixing all the time with salt sea-water, so it might be fractionally less dense than the average surface water density (1.02-1.03), but the absolute lower limit is that 8.5 % will float above the surface, in reality it will be more, and that's entirely without considering the effects of air bubbles.

Rosy, doesn't water compact as it frezzes? shouldn't the density be highier at 0, as the atoms are more compacted, than at 4 ^oC?

If it is a little higher density at 4 ^oC than at 0^oC that suggests the water compacts as it warms. Doesnt it? Or is it that as the ice melts or starts to, air is realesed and the water comes closer together? That would work from Ice to water but not the other way round.

[rosy]

Rosy, doesn't water compact as it frezzes? shouldn't the density be highier at 0, as the atoms are more compacted than at density at 4 oC?

No. Water doesn't compact as it freezes, and the maximum density of water occurs at 4 ^oC. Water's funny stuff. I'm not going to try to explain in any detail here, because it needs diagrams, but there's lots of information on the internet about this. For example this page: http://kentsimmons.uwinnipeg.ca/cm1504/water.htm

On a more hands-on level, consider an ice cube made in your freezer to cool a drink. Not being made from snow, it doesn't contain (a significant number of) bubbles, and yet it floats. If you think about it, I'm pretty sure this is something you know and understand! The density of ice is, inherently, less than that of water at the same temperature. Equally, if you close up a bottle full to the top with water at room temperature (using a plastic bottle is important for safetly..), and freezing the water, the bottle will split as the water expands on forming ice... which shows you that the same mass of water takes up more space (is less dense) when frozen than as a liquid.

Incidentally, if ice didn't float, and if the coldest water didn't float on top of water at 4 ^oC, then the coldest water would sink to the bottom of lakes and rivers, and they'd freeze from the bottom up. That would mean that instead of a layer of ice over liquid water the whole of the lake would freeze, which would kill the fish and other animals living in the water whereas in reality they can hide in the relatively warm water at the bottom until spring.

[Pete Ridley (OP)]

Hi Wiybit, sorry that I didn’t have time to respond straight away to the points you raised on 16/04/2011 @ 20:48:50 and today @ 13:40:20. I don’t want to get distracted from the focus of my question about “Another Hockey Stick Illusion?”, i.e. why the “experts” ignore kinetic in favour of collision diameter. If it’s OK with you I’ll leave it to the Naked Scientists to respond to any that I see as a side-issue. You may have to raise such questions separately in order to attract their attention.

.. Seriuosly you shouldn't encourage them(if you get me) ..

is not the reason that I joined this blog. I will do my utmost to encourage The Naked Scientists to offer their expertise where it relates to my question. I’m very disappointed that I’ve had nothing from them yet and the appropriate laws of molecular dynamics covering the movement of atmospheric gases in firn are certainly relevant.

.. BC can be slightly funny at times, but generally he's ok, when not .. trying to catch you out(so he can laugh at you) ..

is fine for anyone who has come here to be amused but I’m not in that category. I’m here to learn as much as I can about the science relevant to my question. So far the only person on this blog to help improve my understanding is you through your questions.

Regarding

.. you still haven't said what it is about Co2 that causes it to act so differently to the other elements, surely HE should move more, in ice if it's smaller and lighter? ..

one day I may be able to fully answer the first part with confidence. All that I can say for the moment is that it is something to do with the bonding between the one C and two O atoms that make up a molecule and the interaction of each molecule with other molecules (N2, O2, Ar, CH4, H2O, etc. Why not put that question to The Naked Scientists.

As for the second part, He, being smaller even than CO2, does experience size-dependent fractionation, as described in the paper “Evidence for molecular size dependent gas fractionation in firn air derived from noble gases, oxygen, and nitrogen measurements” by Huber et al (http://icebubbles.ucsd.edu/Publications/Huber_closeoff_EPSL2006.pdf).

It is worthwhile looking more closely at that paper, because as well as answering your question about He directly, it expands on my earlier comment (on 14/04/2011 21:38:13) about Huber, Severinghaus (one of the co-arthors) and that magic 0.36nm molecule diameter

Abstract .. For smaller gas species (mainly He and Ne) the fractionation factors are linearly correlated to the molecule size, whereas for diameters greater than about 3.6 Å the fractionation seems to be significantly smaller or even negligible ..

Note that Table 2 presents the molecular diameters used in their model and the close-off fractionation factor it produced for 8 of the atmospheric gases, including CO2 and He, but also note that those diameters are collision, not kinetic. Fig. 8 presents a useful graph of 7 of those computer-modelled close-off fractionation factors, with He down at the bottom of the curve, but note which one is missing, dear old CO2. I mentioned in that earlier comment that I had asked Severinghaus why he used collision rather than kinetic diameter and if he had tried his model using CO2’s 0.33nm kinetic diameter instead of its 0.39nm collision diameter. As I said, he chose not to respond directly to those questions. Have a guess where CO2 would have been if he had used kinetic diameter, which I hypothesise is the appropriate measure.

That is why I challenge the conclusion that

.. Close-off fractionation factors for different gases depend strongly on the diameter. The mass of the molecule is less important, since the effect on isotope ratios is very low. The critical size of about 3.6 Å seems to be an upper limit up to which molecules fractionate during the close-off process in the firn. A possible explanation for this could be the diffusion of molecules through channels in the ice lattice. From our findings we believe that the effect of close-off fractionation is nonexistent or at least very small for isotope ratios and for large molecules, like Xe, Kr, N2, CO2, CH4, and N2O. This is an important confirmation for the integrity of polar ice cores as a climate archive of the ancient atmospheric composition of these gases ..

But I’m only a retired Chartered Electrical Engineer and Geezer reasonably says

.. I find it interesting that anyone who is unaware of why ice cubes float in water might think they are qualified to call into question the scientific credentials of anyone else ..

That is why during the past year I have requested help from “experts” like Severinghaus, Alley, Bender, etc. etc. etc. and now from this “ .. media-savvy group of physicians and researchers from Cambridge University .. ”, but I’m still not getting an answer.

BTW, that paper also gives figures for

.. Firn density at surface [g/cm3] 0.40 0.32 .. Firn density at close off [g/cm3] 0.838 0.811 ..

which you (and others here) should find helpful.

Best regards, Pete Ridley.

[Geezer]

On a more hands-on level, consider an ice cube made in your freezer to cool a drink. Not being made from snow, it doesn't contain (a significant number of) bubbles, and yet it floats. If you think about it, I'm pretty sure this is something you know and understand! The density of ice is, inherently, less than that of water at the same temperature. Equally, if you close up a bottle full to the top with water at room temperature (using a plastic bottle is important for safetly..), and freezing the water, the bottle will split as the water expands on forming ice... which shows you that the same mass of water takes up more space (is less dense) when frozen than as a liquid.
 

Another common demonstration of this phenomenon, well known to scientists and plumbers, is a burst pipe caused when the water in the pipe freezes. The expansion of the ice quite literally rips the pipe apart.

[Jolly- Joliver]

Rosy, doesn't water compact as it frezzes? shouldn't the density be highier at 0, as the atoms are more compacted than at density at 4 oC?

No. Water doesn't compact as it freezes, and the maximum density of water occurs at 4 ^oC. Water's funny stuff. I'm not going to try to explain in any detail here, because it needs diagrams, but there's lots of information on the internet about this. For example this page: http://kentsimmons.uwinnipeg.ca/cm1504/water.htm

On a more hands-on level, consider an ice cube made in your freezer to cool a drink. Not being made from snow, it doesn't contain (a significant number of) bubbles, and yet it floats. If you think about it, I'm pretty sure this is something you know and understand! The density of ice is, inherently, less than that of water at the same temperature. Equally, if you close up a bottle full to the top with water at room temperature (using a plastic bottle is important for safetly..), and freezing the water, the bottle will split as the water expands on forming ice... which shows you that the same mass of water takes up more space (is less dense) when frozen than as a liquid.

Incidentally, if ice didn't float, and if the coldest water didn't float on top of water at 4 ^oC, then the coldest water would sink to the bottom of lakes and rivers, and they'd freeze from the bottom up. That would mean that instead of a layer of ice over liquid water the whole of the lake would freeze, which would kill the fish and other animals living in the water whereas in reality they can hide in the relatively warm water at the bottom until spring.

Like ice in your drink, it floats. I also saw somewhere that water holds it's temperture, which I suppose is why, water in a bottle placed in the frezzer, frezzes around the outside first then moves inward, strange tho I always saw it as cold compresses and heat expands.

As a stab in the dark could it not be a molecular brake down? what I mean is, does the water gives off atoms as it freezes? Meaining you get pockets of oxegen and hydorgen with-in a compressed H2O ice? Expansion comming from having three things H, O and H2o ice, not just h2o water? The atoms individually take up more space then they do binded as water.

So it does compact but breaks down as it does so becomming slightly smaller as ice, but bigger in overall volume beacuse of trapped gases?

 

[Jolly- Joliver]

Hi Wiybit, sorry that I didn’t have time to respond straight away to the points you raised on 16/04/2011 @ 20:48:50 and today @ 13:40:20. I don’t want to get distracted from the focus of my question about “Another Hockey Stick Illusion?”, i.e. why the “experts” ignore kinetic in favour of collision diameter. If it’s OK with you I’ll leave it to the Naked Scientists to respond to any that I see as a side-issue. You may have to raise such questions separately in order to attract their attention.

.. Seriuosly you shouldn't encourage them(if you get me) ..

is not the reason that I joined this blog. I will do my utmost to encourage The Naked Scientists to offer their expertise where it relates to my question. I’m very disappointed that I’ve had nothing from them yet and the appropriate laws of molecular dynamics covering the movement of atmospheric gases in firn are certainly relevant.

You didn't get me, I meant encourage them to argue, Ref: your past complaint.

.. BC can be slightly funny at times, but generally he's ok, when not .. trying to catch you out(so he can laugh at you) ..

is fine for anyone who has come here to be amused but I’m not in that category. I’m here to learn as much as I can about the science relevant to my question. So far the only person on this blog to help improve my understanding is you through your questions.

They(the others that have replied to you) would probably argue that they have tried to help you, but that you have not understood their answers, I will say having some experience of this type of issue, that both side often have a part to play in better communication.

You jumped in quiet early and accused BenV of knowing nothing, he could have just not had time to check in, not to say that others couldn't have responded, but at the same time this is a public family educational forum and there are not so many scientists among the many posters on here, there are many people with a general interest in science but as a percentage I think you'll find the majority of posters on here are interested in science but not actually scientists, I'm not actually sure of the actual numbers of actual scientists on here, not forgetting that most of the scientists on here are specialised in certain fields.
But I am sure they are always looking for more scientists to join, I tried to get a girl studying biotechnology to join the other day.

Also not forgetting the time issues, scientists that do post on here are doing so in their spare time generally. 

Regarding

.. you still haven't said what it is about Co2 that causes it to act so differently to the other elements, surely HE should move more, in ice if it's smaller and lighter? ..

one day I may be able to fully answer the first part with confidence. All that I can say for the moment is that it is something to do with the bonding between the one C and two O atoms that make up a molecule and the interaction of each molecule with other molecules (N2, O2, Ar, CH4, H2O, etc. Why not put that question to The Naked Scientists.

But it relates to your general question, and is only an issue "if" kinetics of Co2 in ice are true, and as far as I can tell that is still part of your main question and so not answered either. Surely first we find out if the kinetic factors are real then ask why does the Co2 move. I asked you because I believed you understood the kinetic science but didn't understand why they ignored it.

As for the second part, He, being smaller even than CO2, does experience size-dependent fractionation, as described in the paper “Evidence for molecular size dependent gas fractionation in firn air derived from noble gases, oxygen, and nitrogen measurements” by Huber et al (http://icebubbles.ucsd.edu/Publications/Huber_closeoff_EPSL2006.pdf).

It is worthwhile looking more closely at that paper, because as well as answering your question about He directly, it expands on my earlier comment (on 14/04/2011 21:38:13) about Huber, Severinghaus (one of the co-arthors) and that magic 0.36nm molecule diameter

Abstract .. For smaller gas species (mainly He and Ne) the fractionation factors are linearly correlated to the molecule size, whereas for diameters greater than about 3.6 Å the fractionation seems to be significantly smaller or even negligible ..

Note that Table 2 presents the molecular diameters used in their model and the close-off fractionation factor it produced for 8 of the atmospheric gases, including CO2 and He, but also note that those diameters are collision, not kinetic. Fig. 8 presents a useful graph of 7 of those computer-modelled close-off fractionation factors, with He down at the bottom of the curve, but note which one is missing, dear old CO2. I mentioned in that earlier comment that I had asked Severinghaus why he used collision rather than kinetic diameter and if he had tried his model using CO2’s 0.33nm kinetic diameter instead of its 0.39nm collision diameter. As I said, he chose not to respond directly to those questions. Have a guess where CO2 would have been if he had used kinetic diameter, which I hypothesise is the appropriate measure.

It's never a good sign if a scientist ignores your question relating to their research, it's either an unknown variables or maybe he felt he need time to formulate a responce and so felt it was too much hassle. Under the law apparently the see silence as agreement, so a non reply could be seen as an acknowledgement that the research wasn't so good; But I cannot speak for him. 

That is why I challenge the conclusion that

.. Close-off fractionation factors for different gases depend strongly on the diameter. The mass of the molecule is less important, since the effect on isotope ratios is very low. The critical size of about 3.6 Å seems to be an upper limit up to which molecules fractionate during the close-off process in the firn. A possible explanation for this could be the diffusion of molecules through channels in the ice lattice. From our findings we believe that the effect of close-off fractionation is nonexistent or at least very small for isotope ratios and for large molecules, like Xe, Kr, N2, CO2, CH4, and N2O. This is an important confirmation for the integrity of polar ice cores as a climate archive of the ancient atmospheric composition of these gases ..

You know if you keep this up you could publish your own findings, you might need some assistance in generating a scientific paper, but why not?

That is how a lot of science moves and works today.

But I’m only a retired Chartered Electrical Engineer and Geezer reasonably says

.. I find it interesting that anyone who is unaware of why ice cubes float in water might think they are qualified to call into question the scientific credentials of anyone else ..

That is why during the past year I have requested help from “experts” like Severinghaus, Alley, Bender, etc. etc. etc.

Well it is a rather meany thing to say, and surely depending on fields lots of scientists do not understand different areas of science, not understanding certain processes even simple ones like why ice floats hardly makes a person stupid, or incapable to see a bad decision made by a doctor and so seek a second opinion as a simple example.
Could be seen as a elitist statement but Geezer isn't that bad, even if the old stick waving git animaton gives that appearence. I know you pain tho.

It's weird how just comming from different places and ways of thinking about subjects causes terms and there meanings to be interprited differently. What I will say is that it appears you have been asking about this for a while in many different places and become a bit "battle hardened", reactions come from actions and all sides are often guilty of over reacting to some degree at times, just chill, getting upset does nothing to futher investigation and often will draw coversations to a close(and there are some that like to cause conflict to achieve that end).

and now from this “ .. media-savvy group of physicians and researchers from Cambridge University .. ”, but I’m still not getting an answer.

Well Chris is the founder and he is involved in medicine and biology I believe, So I doubt Global warming is his field, I do not know if there are any climatologists actually on here, hence which ever of the scientists answer you, they will all probably be working outside their main fields. It appears you think that all the cambridge scientists are involved with the site but it's a voluntary forum, ergo I think many are not.

I can see what you are looking for, someone that knows their field and can answer the questions you have, this site is connected to Cambridge, so potentially there might be someone that knows someone who get you an answer. 

But understand that tho, it was your assumption that whole of cambridge uni science wing posted on here. Rather, the people that do, are doing so to help out and out of their own free time.

that ofcourse is what I believe, I cannot speak for NS, it's just my interpritation having been on here a while. But you know, they do so to help out even if they cannot answer all your questions atleast they try to.

[Jolly- Joliver]

Actually Pete lets just ask the main crux of your question.

Why Do climatologists ignore the kinetic movement of CO2 in ice, as that could, and probably does effect the ice core Co2 levels?

Anyone?

[Geezer]

Actually Pete lets just ask the main crux of your question.

Why Do climatologists ignore the kinetic movement of CO2 in ice, as that could, and probably does effect the ice core Co2 levels?

Anyone?

I think that's exactly what Ben said he would followup on.

If Pete was less interested in whizzing all over TNS and those in the "Scientific Community" who are obviously conspiring against him, we could have got there a long time ago without all this infernal palaver. 

[Pete Ridley (OP)]

Hi Wiybit, In your comment of 17/04/2011 @ 21:45:42 you make some fair points that don’t relate directly to my question so I propose to take them over to my other post where I am enquiring into the areas of science where The Naked Scientists are  competent to comment on.
I agree with your comment of  17/04/2011 @ 22:40:44 that we concentrate on the question that I asked here initially.

About my suggestion that you put a question to the Naked Scientists of why CO2 acts in the way that it does you said

.. But it relates to your general question, and is only an issue "if" kinetics of Co2 in ice are true, and as far as I can tell that is still part of your main question and so not answered either. Surely first we find out if the kinetic factors are real then ask why does the Co2 move. I asked you because I believed you understood the kinetic science but didn't understand why they ignored it ..

I thought that I had made it clear that the “experts” to whom I have put my question are aware of the size-dependent fractionation that occurs (in your terminology “the kinetic factors are real”) but use a different (in my hypothesis an incorrect) measure of the estimated size of molecules when modelling their movement within the porous firn.

Collision Diameter:

.. (physical chemistry) The distance between the centers of two molecules taking part in a collision at the time of their closest approach

(http://www.answers.com/topic/collision-diameter#ixzz1Jr9mx600). As I understand it this applies to molecules whizzing about in a space that is large compared to their size, i.e. normal diffusion of gases and in my opinion relevant in the upper levels of an ice sheet.

Kinetic Diameter:

.. The kinetic diameter can be understood as the diameter of a pore needed to let that specific molecule pass ..

(http://www.patentstorm.us/patents/7214719/description.html), in my opinion relevant in the lower levels of an ice sheet as it approaches close-off.

As I have repeated ad-nauseam in my exchanges with the “experts”, kinetic diamter is the measure used by gas purification practitioners in their patented and working purification systems. As the patent above says (albeit in relation to

.. Separating of water .. in particular with H2, CO, CO2, CH4 and higher alkanes ..

(H2O kinetic diameter 0.27nm) 

.. separation on size is possible, when the components to be separated are small enough in kinetic diameter to migrate through the zeolite pores and the components from which they have to be separated have a kinetic diameter that is too large ..

If you want to find out more about the difference between the two measures there is an excellent book “Materials science of membranes for gas and vapor separation” (http://books.google.co.uk/books?id=Hc6ioeRc7p8C&pg=PA8&lpg=PA8&dq=H2O+%22collision+diameter%22&source=bl&ots=p1PsILlfsd&sig=sNWlODlE3Y4gmadOscv_BDvoTRg&hl=en&ei=0OarTanCDIeg8QPA-Oy4Ag&sa=X&oi=book_result&ct=result&resnum=1&ved=0CBYQ6AEwAA#v=onepage&q=H2O%20%22collision%20diameter%22&f=false).   Pages 7-10 and Table 3.1 “Properties of Gases” on Page 96 are particularly relevant and will give you an idea of the complexity of the subject. If I can’t extract an answer to this fundamental question from the ice core “experts” I may well be forced into buying that book and finding an expert in molecular dynamics who is prepared to spend the time giving me

.. some assistance in generating a scientific paper ..

But surely if I have to do that it begs the question “Why haven’t the paleoclimatologists done this already?”. After all, Professor Jaworowski raised this specific fundamental issue of size-dependent fractionation in 1992 and Huber, Severinghaus and their co-authors were researching it at least as long ago as 2004 (http://icebubbles.ucsd.edu/Publications/Huber_closeoff_EPSL2006.pdf).

I agree that

.. It's never a good sign if a scientist ignores your question relating to their research, it's either an unknown variables ..

but do not think, under the circumstances, that they should

.. need time to formulate a responce and so felt it was too much hassle

You and Geezer, appear to defend The Naked Scientists because they may not have expertise in climate science. I would not be here if they had not given me the impression of having a section within their "Environment" area specifically on Climate Change and having their representatives advising on it. If I don’t have expertise then I admit it. Surely it is not asking too much for a simple statement on their “About” page making it clear in what areas they are competent to speak?

Geezer I did not come here for the purpose of

.. whizzing all over TNS and those in the "Scientific Community" who are obviously conspiring ..

As I explained in my opening question

I came across this blog while searching for detailed pictures of ice extracted from deep down an ice sheet. I have a question that has been puzzling me for over a year now and remains unanswered despite asking it of experts in the subject ..

The Naked Scientists gave me the impression of having access to experts in this subject because when I Googled - “Ice Cores” climate – I was taken to

Climate Change and Ice Cores. Dr Eric Wolff from the British Antarctic Survey

(see that lovely picture of bubbles in ice) and thought “Hey, at last I might make headway.

I then looked at TNS’s “About” page (http://www.thenakedscientists.com/HTML/about-us/) and thought “Yes, this is promising” because

The Naked Scientists are a media-savvy group of physicians and researchers from Cambridge University ..

but then I saw the photo and thought “Is this a joke?”. Never mind, I persevered and looked at the

Who are we?”

page (http://www.thenakedscientists.com/HTML/about-us/who-are-we/) and thought “OK, that ‘photo is just high-spirited youngsters having a laugh. There are three archaeologists, a zoologist, a couple of astronomers, all apparently from Cambridge University, with contacts with specialists who can answer my question.

What was the outcome? Only one of those Naked Scientist, their kitchen science specialist BenV, responds, first simply asking

So what's your question here Pete?

despite my question having been spelled out clearly in my first paragraph

.. why do paleo-climatologists use collision diameter in preference to kinetic diameter when considering the migration of air molecules through firn and ice ..

BenV then follows up with

I don't recall claiming any expertise in migration of molecules through any medium, so it's no surprise you find me lacking in that arena ..

Is there any wonder that I might be getting somewhat irritated. I asked a straight forward question of a group who I understood from their own promotional material and the content of their blog could find an answer for me and provided background information about it to help elicit a worthwhile response and all I get is “what was your question” and “I can’t answer it”. If I have over-reacted then I sincerely apologise, but I think I have pointed out here already, I arrived here after already getting rather irritated by “experts” refusing to respond to my simple question about kinetic v collision diameter.

Please Naked Scientists can you find someone who is knowledgeable enough to provide a straight answer to my fundamental question.

Best regards, Pete Ridley

[BenV]

As I said, Pete, I will try to put it to someone relevant when I next have an opportunity.

Also, I explained to you why my first comment was about your specific question - because the huge block of text means some people will not read it, discover your question and engage, and I was subsequently proved to be  correct.  Might I also suggest that your rather aggressive posts may lead to some people who may be able to help being disinclined to do so, and would rather not get involved?

[Pete Ridley (OP)]

Hi BenV, thanks for trying to find someone to whom you can put my question. Hopefully it won’t take you long to find someone who understands the subject and is prepared to spend a little time educating me.

Best regards, Pete Ridley

[Jolly- Joliver]

 

About my suggestion that you put a question to the Naked Scientists of why CO2 acts in the way that it does you said

.. But it relates to your general question, and is only an issue "if" kinetics of Co2 in ice are true, and as far as I can tell that is still part of your main question and so not answered either. Surely first we find out if the kinetic factors are real then ask why does the Co2 move. I asked you because I believed you understood the kinetic science but didn't understand why they ignored it ..

I thought that I had made it clear that the “experts” to whom I have put my question are aware of the size-dependent fractionation that occurs (in your terminology “the kinetic factors are real”) but use a different (in my hypothesis an incorrect) measure of the estimated size of molecules when modelling their movement within the porous firn.

So you are therefore saying that you know why Co2 moves as it does, and know of a better way to model it?

You and Geezer, appear to defend The Naked Scientists because they may not have expertise in climate science. I would not be here if they had not given me the impression of having a to, section within their "Environment" area specifically on Climate Change and having their representatives advising on it. If I don’t have expertise then I admit it. Surely it is not asking too much for a simple statement on their “About” page making it clear in what areas they are competent to speak?

Except enviroment is a huge area of science, I'll defend anyone where I see a need to, I critic also, I just try to be fair that's all.