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Comment on Open thread by Pierre-Normand

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“No – I was talking about the expansion of a real gas into a lower pressure zone amongst other things.”

If it isn’t throttled through some sort of valve or porous boundary so as to maintain constant enthalpy then it isn’t exemplifying the Joule-Thompson effect. If it is expanding while doing work on the surrounding then it isn’t a case of Joule expansion (where the work is zero). You are trying to imagine every possible kind of phenomenon except for the actual one that is simple thermodynamically reversible adiabatic expansion performing work on the surrounding at the expanse of internal energy (which is clearly assumed in the mathematical derivation that you reproduced from Wikipedia without seemingly understanding it at all).


Comment on Open thread by Rob Ellison

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‘Environmental lapse rate – which refers to the actual change of temperature with altitude for the stationary atmosphere (i.e. the temperature gradient)

The adiabatic lapse rates – which refer to the change in temperature of a parcel of air as it moves upwards (or downwards) without exchanging heat with its surroundings. The temperature change that occurs within the air parcel reflects the adjusting balance between potential energy and kinetic energy of the molecules of gas that comprise the moving air mass.’ Wikipedia

The Joule-Thompson effect is about expansion of a real gas. The adiabatic assumption assumes no heat transfer. This is an unlikely assumption as molecules collide with adjacent molecules imparting kinetic energy. However in theory the cooling in an adiabatic process – one that proceeds rapidly enough to limit energy losses – the change in temperature is the result of changes in the balance of kinetic and potential energy on the molecular level. For Doug’s benefit – this is distinct from bulk kinetic and potential energies.

The derivation is based on one from the Arizona State University – worked through to show the error in Doug’s derivation. Confusing Cp with Cv.
But I did suggest P-N try it himself. It assumes as I said constant pressure – PdV – something convenient but obviously not true in the atmosphere. The adiabatic lapse rate is useful for indications of atmospheric stability – but not beyond that.

Insisting dogmatically on a theoretical construct like the dry adiabatic lapse rate – and on one particularly dubious assumption especially – as a complete explanation of atmospheric processes is the sign of a spectacularly inadequate mind.

Comment on My week(s) in review by Steven Mosher

Comment on Open thread by Pierre-Normand

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“Insisting dogmatically on a theoretical construct like the dry adiabatic lapse rate – and on one particularly dubious assumption especially – ”

*What* dubious assumption am I making? You aren’t saying. My main assumption that contradicts your own is the standard quite natural assumption that the expanding parcel of air performs work dW = PdV on the surrounding and this is taken from the internal energy of the parcel. This assumption is formalized explicitly in the mathematical derivation of the lapse rate that you quoted approvingly.

Your own two mutually inconsistent assumptions, either (1) Joule expansion, with dW = 0 — which implies, rather ridiculously, no lapse rate at all, or (2) the Joule-Thompson constant-enthalpy expansion process, that has no physical justification either since the expansion of the rising parcel of air isn’t close to be enthalpy preserving.

You also extracted from Wikipedia the single paragraph that seems out of place (and may have been put there by Doug C. for all we know) and contradicts the assumption about gravitational potential energy that you yourself had endorsed in the mathematical derivation of the lapse rate. There is *no* internal energy change in the parcel of air corresponding to the change in gravitational potential energy, pace Doug C and yourself.

You seem to be reaching in the dark in order to justify some of the indefensible claims that you made. You also never explained *what* kind of “energy” you are referring to that you alleged remains constant while the parcel of air expands and its internal energy, and therefore also its temperature, both drop. Again, internal energy would be constant *if and only if* the adiabatic expansion process would be a process of “Joule expansion”, but in that case dW = 0 and there would be no temperature change within the rising (or descending) parcels and hence no lapse rate at all.

Comment on My week(s) in review by Tom Fuller

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Climateballers are the graffiti sprayers of the climate blogosphere. And you ain’t Banksy, willard.

Comment on My week(s) in review by Tom Fuller

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Perhaps we she published a peer-reviewed paper on the potential for increased hurricane intensity due to global warming? Nah, she’s a denier witch, willard. Bring your matches?

Comment on Open thread by Eric

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Warmest September ever recorded has just occured and yet some people still speak of pauses. The pause talking point has become outdated.

Comment on Open thread by Rob Ellison

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Yep – P-N is back. Saying it again is not interesting. I didn’t actually read much of it – it gets to the stage where you can pretty much know where it is going and I am really not interested in another round of being told I don’t understand what I quote.

He doesn’t get it. He is insisting that something that bears only a passing resemblance to reality is the absolute truth. It is interesting in its way – but a starting point only. I tried to say this a couple of times – it is just getting embarrassing now. He’s worth ignoring – but really – the constant refrain that I don’t understand – or some other disparagement – doesn’t incline me to be too charitable.


Comment on Open thread by Rob Ellison

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Temperature drops with changes in the kinetic and potential energy at the molecular level in a real gas. This was spelled out. More than once.

It get’s to the Monty Python stage.

Comment on Open thread by Rob Ellison

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Temperature change occurs in a real gas – such as air – as opposed to an ideal gas – this was spelt out as well a few times.

Comment on Open thread by Pierre-Normand

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Yes, of course. Suggesting that the Great Chief Hydro misunderstands *something*… He who can picture all the relevant forces and molecular motions in his own private mind’s eye! What contemptible behavior.

Comment on My week(s) in review by beththeserf

Comment on Open thread by Pierre-Normand

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It’s your constantly asserting one thing and then the opposite (or asserting something else that entails the opposite) that’s Monty-Pythonesque. You still decline to provide *any* justification or retraction of your initial claim that “The air is progressively cooler as it rises and expands – but it doesn’t lose energy.”

Did you simply misspeak? Then later you insisted: “We have molecules that expand into larger volume – Joule expansion or free expansion in a lower pressure environment – we simply have the same amount of energy in a larger volume. Hence lower T. As in the ehow quote.”

So, if the amount of internal energy (kinetic + potential energy at the molecular level) in the air parcel remains the same, where does the energy required to perform the work dW = PdV on the surrounding come from? And how do you reconcile this work being positive with the process being a case of “Joule expansion” where, by definition, dW = 0?

Comment on My week(s) in review by A fan of *MORE* discourse

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Judith Curry observes  “Governor Rick Perry gave the evening plenary talk (but first, another state senator offered a prayer) […] it was all about the virtues of Big Oil and Gas”

“This event was steeped in capital R/C Republican/Conservative (much more so than the Marshall Institute event).”Judith Curry, please appreciate the faux-conservative dilemma:

Faux-conservatism has lost the “Culture Clash”  `cuz global marriage rights are a done deal.

Faux-conservatism has lost the “Obamacare Clash”  `cuz global healthcare rights are a done deal.

Faux-conservatism has lost the “Climate-Change Clash”  `cuz global sustainability values are a done deal.

What We’ll See  From (what JC calls) “Big Oil and Gas” — *MUCH* asset-protecting slogan-shouting, *LITTLE* scientific discourse, and *ZERO* effective actions.

*EVERYONE* appreciates these three realities, eh Climate Etc readers?

STEM students and STEM professionals, especially!

The Big Question  What is the future of rational, science-respecting, morally grounded conservatism?

The world wonders!

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Comment on Open thread by  D o u g  

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Pierre. If you start with a state of thermodynamic equilibrium in a column of air (such as can be closely attained towards the end of a calm night) then nothing happens until a new source of thermal energy (the Sun rising) provides all the energy that is needed to do whatever subsequently happens. Assuming the state of thermodynamic equilibrium is disturbed, and the new source of thermal energy stops (that is, the Sun sets) then the column of air will tend towards a new state of thermodynamic equilibrium with the same temperature gradient but a higher temperature at all points. So, assuming otherwise calm conditions (no wind energy being added and so no bulk KE) what happens is all diffusion and (usually) some advection. The term “convection” in physics embraces both.


Comment on Open thread by Pierre-Normand

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Someone wrote: “Read my book and you will see I have not been talking about bulk kinetic or potential energy at all, but just exactly what your Wiki quote mentions – mean KE and PE per molecule.”

The user who introduced this paragraph in the Wikipedia “Lapse Rate” article mentions the motivation for his addition in the talk page. This person clearly has the bulk (organized) kinetic energy of the parcel of air as a whole confused with the sum total of the kinetic (disorganized) energies of the component molecules. As Pekka Pirilä pointed out in another thread, externally driven (e.g. though buoyant force) vertical displacement of bulk *solids* in the gravitational field lead to variations of potential energy that aren’t compensated by variations of kinetic energy of the component molecules. The same holds of macroscopic parcels of air in the atmosphere. It’s only work performed through expansion (or contraction) on the surrounding that’s responsible for the change in internal energy. (Also, gravitational potential energy of component molecules isn’t part of internal energy at all.)

See the thread “The lapse rate” on ATTP’s blog more more thorough explanation of this point by Pekka.

Comment on Open thread by Pierre-Normand

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Introducing close range inter-molecular forces doesn’t justify any of your heterodox claims, so far as I can see. You don’t even attempt any such justification. The normal expansion (with dW 0) doesn’t become Joule expansion (dW = 0) just because the gas isn’t ideal.

Comment on My week(s) in review by TJA

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Your moral preening and moral case for action on climate change would ring a lot less hollow, we you able to articulate a technical case for it beyond “look at that blade!”

The Hockey Stick for you guys is l like those images of Jesus or Mary that appear in the mold on the wall in the basement of some tenement. You believe it so you see it. The rest of us would like a more convincing technical case before we throw out the greatest force for the betterment of mankind in the history of mankind.

Comment on My week(s) in review by TJA

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Michael Mann, I guess.

Comment on My week(s) in review by Michael

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John Smith (it’s my real name) | October 13, 2014 at 12:52 pm |
“Michael, what specific news outlets have given C. Monckton attention not offered to the other side?”

Nice goal post shift John.

Your original assertion implied that there was no MSM coverage of ‘skeptics’ – easily shown to be ‘not even wrong’.

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