O:H-O Bond Anomalous Relaxation Resolving Mpemba Paradox
Mpemba Effect on Wiki
It's an observation that's 2,500 years old.
A Note: Global Warming Threads
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Mpemba Effect on Wiki
It's an observation that's 2,500 years old.
I'm swamped with a deadline, ironically on nearly the same subject. Anyway maybe try Zamelczyk et al. 2012. page 412
If a prize was offered in the contest I wish I had known of it in time to enter as I developed an explanation many years ago, that I think better than that of the contest winner or your first link.
It is based on the easily demonstrated fact that moment in water takes surprisingly long to become insignificant. For example false claims / predictions are often made that water will drain out of a basin clockwise or counter clockwise depending upon which hemisphere the experiment is done in but that very weak Coriollis effect is completely over whelmed in a hemispherical bowl with tiny stopper closing hole at the lowest point by giving the water a not even noticeable angular moment, even if the gentile stirring ended an hour before the stopper is removed to allow draining to start. The last water to drain out will do so with rotation of the same sense as the weak stirring had.
As Mpemba's effect is normally demonstrated the two beakers have well insulated bottoms (sit on thick Styrofoam etc.) so the heat loss is at the sides and top. (possibly more at the sides if beakers are metal). In any case a circulation patter will develop with bottom water rising in the center as the cooling water falls down along the circumference. This circulation has more momentum when the beaker's surface water pass thru 4C in the beaker that was initially hotter as the thermal gradients building the momentum are much stronger in that beaker. At 4C and below, the density of water increases so the 4C water which has been accumulating at the bottom of the beaker aids the pre-existing circulation just as the thermal gradients that initially drove it are growing weaker.
SUMMARY: The circulation, bring warmer water (as it removes cooled water) into contact with the thermal transport surfaces is stronger, and remains stronger in the initially hotter beaker until the water freezes. Thus, even though the initially hotter beaker has more heat to lose in order to freeze it is always losing it faster than the initially colder water beaker. If the initial temperatures are correctly chosen, the hot water will freeze first due to the higher cooling rate.
Impressive Billy, if I understand correctly, it's the inertia momentum of the convection that does it. I had similar thoughts, although I was considering that the turbulence due to the convection would prevent supercooling, while clear and totally static water can supercool quite a bit amazingly. But that was a mere guess, the start of the scientific method.
Okay so obviously convection is a strong mechanism. Another experiment to support that. Light a simple candle and move your index finger horizontally to the flame until the heat warns you that you're about to close in too much. That may be around half an inch or so. So that's the heat transfer your index finger can tolerate from infrared radiation alone, the satanic gasses mechanism that's going to boil our planet. Now repeat the experiment from above the flame and try to match that same half inch above the flame (no don't try that). If you managed that same half inch you'll need first aid for burn wounds but it makes clear how much more important convection is for heat exchange than infrared radiation. And that's where the global warming alarmism goes wrong.
To be continued.
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You appear to be suggesting that climate scientists are unaware of the difference between the effects of infrared and heat convection.Andre said:
Which if true, says you are full of arrogant bullshit.
Can't wait.
To investigate the role of convection, we would need a simple basic model, where we can put convection in, however if we look at the simple basic model explaining greenhouse effect, there is no talk about convection at all:
Billy I know that you like to challenge people to think, so do think, What else is wrong with that model?
Either you've misunderstood the source, bought into propaganda, or ate misrepresenting it.
The simple fact of the matter is that climatologists have been using radiative-convective models since the '70s.
EG:
climate modelling through radiative-convective models
Ramathan & Coakley Jr.
Reviews of Geophysics.
Volume 16, Issue 4, p465-489
November 1978
It seems a distinction needs to be made between the mechanism by which CO[sub] 2[/sub] absorbs heat energy in the first place, and how that heat energy is distributed.
Thanks for that study. Very interesting. I note that they do bring convection in the equation, but also that they assume a strong negative feedback from clouds and that they note climate sensitivity at around the lower estimates of the IPCC. I also could not find where they explain difference between grey body equilibrium temperature and the average global temperature as pure greenhouse effect
But that's not the issue at hand. Let's try to start from scratch with a real null hypothesis, that is, what would happen to earth global temperatures when there were no radiative active gasses in the atmosphere, let's say a pure nitrogen atmosphere?
That's only a question and NOT
But that's not the issue at hand. Let's try to start from scratch with a real null hypothesis, that is, what would happen to earth global temperatures when there were no radiative active gasses in the atmosphere, let's say a pure nitrogen atmosphere?
That's only a question and NOT
So? Nobody I know of has ever claimed that the ice regime of the past 1000 years was the smallest extent ever. There's no surprise in discovering "extended periods" of less ice and more open water than the norm of the past millenium. To repeat:andre said:
The ignorance of experts is not an argument for anything you post here.andre said:
Otherwise:
I'm not claiming that there are no circumstances under which a somewhat warmer glass of water would freeze before a somewhat colder one. All I am saying is, concluding that warmer water freezes faster than colder water is not reasonable.trippy said:
Try this: fill two racks of test tubes with water, cotton batting plugged. Put one in the freezer, wait a half hour, put the other one in - the claim is that the second one will freeze sooner than the first one. Now try it with all the test tubes individually - put them in the rack one at a time, in the freezer, at five minute intervals. The claim is that they will freeze in reverse order - last one in freezes first.
It can get worse: put a large tank of 99C water in a meat locker, and set a small test tube of 1C near-but-not-quite-frozen water on the other side of the same room - and watch that tank freeze in five minutes? The heat release from that would be nearly explosive.
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That's because there's actually two approaches to the problem.
One approach is to treat the atmosphere as a grey-body, for example, Ingersoll AP, 1969: Runaway greenhouse - a history of water on Venus. J. Atmos. Sci. 26, 1191-1198.[/quote].
This approach, even though it is the approach that lead Hansen to make his predictions of Venusian doom based on a runaway greenhouse effect is known to be inaccurate. It is widely known to be inaccurate, to the point where Hansen even publicly acknowledged that it was inaccurate.
The more accurate approach is to use the CKD approach (or the cumulative K distribution approach) which was, for want of a better word, championed by James Kasting. This 1988 paper by James Kasting:
[url=http://www.chriscunnings.com/uploads/2/0/7/7/20773630/runaway_greenhouse_venus.pdf]Runaway and Moist Greenhouse Atmospheres and the Evolution of Earth and Venus: Icarus 74, (1988)
This model is a convective-radiative model that uses longwave spectrum based in absorption data rather than making the grey-body assumption.
I imagine, based on my understanding of the Stefan-Boltzman law, taking into account the earths albedo and emissivity, and assuming the atmosphere is completly transparent to longwave IR radiation, that the earth would cool by some value less than it's current value, but such that the out going radiation (reflected + Emitted) is equal to the incoming radiation recieved by the sun (as required by the conservation of energy). I would also expect that some parts of the surface would be hotter than the earth's effective temperature, and some parts would be cooler, giving an average temperature close to the effective greybody temperature.
That's fine. You're not asking anything unreasonable nor anything I myself have not asked or wondered, but understand this: I have been a member of this forum since 2007, and a moderator of this forum since 2008-ish.
In my time as such, I have - in the course of the discussion around whether or not anthropogenic global warming is real, had this discussion with a range of interloqutors that have presented arguments including "The book of genesis says... Therefore humans aren't causing global warming." Or "There are hydrocarbons on Titan, are you telling me that there is life on Titan LOL!" I'm not the only person in this discussion in that boat. Iceaura, for example, has been party to many of the same discussions. So forgive us our skepticism.
And yet that's the observation, and there are any number of sources that can support this. For example: Can hot water freeze faster than cold water?
No, because they started at the same temperature. They're freezing from the same temperature, so they take the same amount of time.
Again, no, and this isn't what I said. From the source I linked to:
Look, all I did was point to the Mpemba effect and suggest that if some of the warmer water - be it surface water or deep water, were 'leaking' past the circumpolar current, then that might provide part of an explanation as to why antarctic sea ice appears to be growing rather than shrinking. I then pointed to the paper from 1977 which seams to suggest that sea ice thickness (and therefore growth), although it requires near freezing conditions is governed by the radiative equilibrium between the top surface of the ice and the bottom surface of the ice.
It was a suggestion based on a 2,500 year old observation combined with a modern observation. I'm perfectly fine with the suggestion being wrong, I just think that its relevance bares consideration.
It is grossly over simplified. Too much omitted that is important, and as I don't have time or inclination to discuss all the major errors, I'll just note that the earth is not isothermal, and that is important when speaking of T^4 radiation. Yes convection is important, both in air (Typhoon Haiyan redistributed more energy than all the hurricanes of the Atlantic Ocean did in 2012!) and in oceans - England would be much colder without the gulf stream and west coast of Norway ice clogged year round, I think.
On the Mpemba effect, I neglect supper cooling in my discussion as if ordinary tap water is used I think both beakers will be starting to freeze before temperature falls below -0.1C and that the difference between their supper cooling is negligible.
You need a better translator.
This is more interesting than whatever bs Andre is pushing nowdays:
Re the sequential test tubes in the freezer:
Clearly we have a problem of definition with regard to "start", but the definable moment is the initial one when all the bodies of water being compared have begun the process of freezing together.
As Billy's proposed mechanism illustrates, it isn't as easy as it looks to isolate the temperature as a factor here - in particular, creating the warmer water by heating a sample introduces variables from evaporation to degassing to hidden momentum in the water. I would choose to create the initial temperature difference by cooling a randomly chosen sample of the water, using a container shape that does not abet convection, and so forth.
No, the observation is that if you are careful things can be arranged so that a warmer quantity of water will end up freezing faster than a cooler one. That is not the same as claiming that warmer water freezes faster than cooler water.
Re the sequential test tubes in the freezer:
They are not "started" from the same temperature - the ones prepared by cooling them in advance (in the freezer earlier, a convenient way to arrange that) will be cooler when the later entries are put in and the comparison starts, so they will take longer (if the water temp is the significant variable, and the effect holds).trippy said:
Clearly we have a problem of definition with regard to "start", but the definable moment is the initial one when all the bodies of water being compared have begun the process of freezing together.
As Billy's proposed mechanism illustrates, it isn't as easy as it looks to isolate the temperature as a factor here - in particular, creating the warmer water by heating a sample introduces variables from evaporation to degassing to hidden momentum in the water. I would choose to create the initial temperature difference by cooling a randomly chosen sample of the water, using a container shape that does not abet convection, and so forth.
Now there you unleashed quite something. So there are the experts who study the rotation of Venus this for instance, the idea being that Venus could have spinned as a protoplanet, then we have the experts who study the Venology, Vicky for instance, who concluded that the surface temp must have been extremely high in the past and then of course the most popular study of its atmosphere as referred to.
Now what would happen if all those specialists came out of their niches and studied the other niches, could it be possible that they could come to a unified Venus explanation? Hint, where is the rotational energy of Venus?
More later, the signifant other has ordered so.
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Here is my take.
If there are no radiative active gasses in the IR spectrum, the only way that the atmosphere can exchange energy is conduction with the surface. whenever the boundary layer of atmosphere has a different temperature than the surface. Internally within the atmosphere, there can also be heat transport by advection and convection, but there is no out radiation by definition.
Another element, not always found in models, is the diurnal cycle. Earth is not getting, some 340 W/m^2 energy on the average. Instead, at the day side of the planet there is anything from 0 to some 1360 W/m2, while at the night side it is zilch, not counting cosmic background radiation. If you apply Stefan Boltzmann on a grey body with the normal albedo/reflectivity, the absorption-emission equilibrium temperature of the zenith spot on Earth is close to boiling temperature, like it is on the moon.
So, at the day side, especially at that near boiling hot spot, the incoming short wave energy is converted to heat and consequently to long wave radiation out as well as thermal conduction to lower layers and thermal conduction to the lowermost boundary layer of the atmosphere. As this boundary layer becomes less dense with warming, it starts a convection cycle, the effectiviness depending on lapse rates and adiabatic expansion and compression (only dry adiabats for N2 as there is no water vapor in our greenhouse gas less null hypothesis), the main thing is though that thermal energy is entering the atmosphere and penetrates higher levels by convection.
So the planet rotates and soon this spot is at the night side. The earth surface is now still losing thermal energy by radiation. As the surface cools, so does the lowermost atmospheric boundary layer. So that gets denser and therefore stays put. We see that on real earth also as a thermal ground inversion.
But this inversion also blocks heat exchange with higher atmospheric layers, which again, can only exchange thermal energy via conduction with the ground. No radiation out to space, no radiation to the surface. Hence most of the thermal energy that goes into the atmosphere at daytime stays there at night time, there is no negative convection.
So we have an unbalance in the atmosphere here, a certain amount of energy in at daytime, and hardly any out at night time. Balance will be restored when the atmosphere contains so much thermal energy that convection is suppressed and limited to what can be re-conducted out at night time.
At what thermal energy content for the amosphere is a guess, a challenge for modellers, but I doubt if it's lower than the current energy content of the atmosphere. So maybe an inert atmosphere is warmer than an atmosphere with radiative properties.
If this sounds toe curling counter intuitive, please don't shoot the messenger, just go over the logic and challenge it. There is plenty to discuss.
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You've had enough chances to engage in honest and logic based discussion on this forum. You are not a messenger, and people should not allow themselves to be conned into wading through your piles of bs:andre said:
and bothering to, say, point out that you have apparently postulated a perfect insulator - a solar-heated ball of gas that can float around in deep space forever without ever cooling off - and then claimed significance for its failure to cool off, or any of the other absurdities of logic and irrelevancies of claim buried in that pile,
only to find you once again simply changing the subject, most likely by asking Foxtype questions about something else and tail-chasing some string of innuendos.
So what exactly is wrong with the logic?
Or are we dealing with a mindguard action against a folk devil in the outgroup*?
Can we stick to physics please? What exactly is wrong there?
Moreover, about changing subjects, the null hypothesis is a fundamental issue. If GHG is doing something something to the climate, what if there was no GHG? How does that compare to a totally irrelevant Mpemba effect to this issue?
*symptoms of groupthink
Or are we dealing with a mindguard action against a folk devil in the outgroup*?
Can we stick to physics please? What exactly is wrong there?
Moreover, about changing subjects, the null hypothesis is a fundamental issue. If GHG is doing something something to the climate, what if there was no GHG? How does that compare to a totally irrelevant Mpemba effect to this issue?
*symptoms of groupthink
Aside from this point:
On your point regarding the Stefan Boltzman law, however, what you've said is incorrect. The diurnal cycle of the earth is inherently taken into account. The area used for calculating the energy recieved is that of a circle, where the area used for calculating the emission is that of a sphere. In other words, the calculations assume that only the side facing the sun receives energy, but the energy is emitted uniformly in all directions.
Also note that this diagram:
Shows the earth's grey-body emission over a 100k range from 37°C to -63°C
Consider the behaviour of deserts on earth, for example.
Most of you post deals with the mechanisms of heat transfer and redistribution, which are in essence the detail of how this would occur:
On your point regarding the Stefan Boltzman law, however, what you've said is incorrect. The diurnal cycle of the earth is inherently taken into account. The area used for calculating the energy recieved is that of a circle, where the area used for calculating the emission is that of a sphere. In other words, the calculations assume that only the side facing the sun receives energy, but the energy is emitted uniformly in all directions.
Also note that this diagram:
Shows the earth's grey-body emission over a 100k range from 37°C to -63°C
Without IR Active gasses, how does the inversion layer prevent the raidative IR emission of heat energy into space?
Consider the behaviour of deserts on earth, for example.
That greenhouse gasses absorb IR wavelengths of a given wavelength is an observable, empiricaly verified fact predicted by simple harmonic motion and consequently Quantum Mechanics.
If those predictions were wrong, we wouldn't have had to launch Spitzer into space, we could have operated the observatory from the ground:
The predictions can be confirmed by anyone with access to an IR spectrometer capable of assessing the appropriate wavelengths:
That's kinda what we were discussing, including, to some extent, whether or not it was actually relevant. The Mpemba effect is that under some conditions water that has been heated will freeze faster than water that has not been. We were discussing whether or not it might be an influence in Antarctic sea ice growth in the context of Stefans law as presented in the 1977 paper I linked to.
:Sigh:
Commentary such as this is un-neccesary, inflammatory, and only serves to diminish your position.