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Comment on Ethics of communicating scientific uncertainty by captdallas2 0.8 +/- 0.2

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P-N, “If one considers a piece of isothermal air column enclosed in a box, then the molecules will have the same average kinetic energy at the top as they have at the bottom.”

Consider a tall container with just one molecule bouncing from bottom to top under gravity. Because of the acceleration of gravity, the molecule will impact the bottom harder than the top. Once that example is “isothermal”, the molecule would be at rest on the bottom. As long as “isothermal” doesn’t mean absolute zero, there will be motion and gravity will have some impact on that motion until all the molecules are closely packed on the bottom.

As I said earlier, the garvito-thermal effect is very small since molecules have very small mass and limited mean free path if there is any significant concentration. That doesn’t mean that gravity isn’t still a part of nature.


Comment on Climate Dialogue: influence of the sun on climate by Wagathon

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Global cooling need not be the <em>wreck of hope</em>. What do we do? Humanity needs more energy and we'll need even more so we can produce more during shorter growing seasons and to last long winters when it could get cold enough to freeze the UK's Thames river again, as it last did not long ago during the <a title="Dalton Minimum" href="http://en.wikipedia.org/wiki/Dalton_Minimum" rel="nofollow">Dalton Minimum</a> (1790–1830). The last big chill occurred at a time corresponding with a period of reduced solar activity – measured by fewer sunspots – as also occurred before that, during the <a title="Maunder Minimum" href="http://en.wikipedia.org/wiki/Maunder_Minimum" rel="nofollow">Maunder Minimum</a> (1645–1715 ) and <a title="Spörer Minimum" href="http://en.wikipedia.org/wiki/Sp%C3%B6rer_Minimum" rel="nofollow">Spörer Minimum</a> (1460–1550). “My opinion is that we are heading into a Maunder Minimum,” according to Mark Giampapa (solar physicist at the National Solar Observatory). “I’m seeing a continuation in the decline of the sunspots’ mean magnetic field strengths and a weakening of the polar magnetic fields and subsurface flows.”

Comment on Ethics of communicating scientific uncertainty by Pierre-Normand

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captdallas: “It is wrong because you are not solving the same problem Rob posed.”

We are looking at the same problem, and evaluating the end state after the “compressed gas” has cooled at the same temperature. I don’t think the gas remembers that it was warmer in the past, though I understand it’s part of the argument for the conclusion. Still, I am evaluating the end state: two containers of identical volume, same temperature, and pressures 1atm (“uncompressed”) and 2atm (“compressed”). I am saying that they have the same average kinetic energy per molecule but I now see that you really are agreeing with Rob.

“Temperature is a measure of the average energy of collisions. You can have lots of collisions with lower energy or fewer with more energy.”

Yes, this seems to agree with Rob. I am denying this. I am rather going with standard physics textbooks and saying that (kinetic) temperature is a measure of average kinetic energy per molecules. This is standard classical statistical and thermal physics, not QM.

“So you are looking at the average energy per container not the average energy per molecule.”

Do you mean the volumetric density of kinetic energy? Or the gross molecular flux of KE per surface area units? The latter, not the former, would relate rather more to the collisions with the surface, though it seems irrelevant to temperature, in my opinion. (It is relevant to rates of heat transfer).

“The 2g container has twice the molecules at half the energy per molecule.”

So you also are agreeing with Rob that both containers have the same total thermal energy content.

This would mean that the container with twice the molar amount of air (hence twice the mass), at the same temperature, though twice the pressure, has the same total internal energy content.

Are you really believing this to be true?

“Sometimes it is better to start simple, restate the actual problem and use the simplest approach before jumping into quantum physics.”

Agreed.

Comment on Climate Dialogue: influence of the sun on climate by aaron

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The Dianetics of Climatology.

Comment on Root Cause Analysis of the Modern Warming by Whether or not Global warming will be large or small I have a big problem anyway | TryingToUnderstandItAll

Comment on Root Cause Analysis of the Modern Warming by IPCC claimed “certainty” but it is clearly provable that 10 years later certainty is still not the case | TryingToUnderstandItAll

Comment on Ethics of communicating scientific uncertainty by captdallas2 0.8 +/- 0.2

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P-N, if you don’t like the basic, boring explanation of temperature then use entropy, which container has less entropy? The one with more molecules per unit area or the one with less? If you don’t like collisions how about molecular vibration in the temperature sensor. No matter how you slice it once you contain a gas you are looking at the container temperature.If you strap a thermocouple to the outside of the container you will measure the temperature of the container allowing for insulation of course. Not one gas molecule has to impact that thermocouple for you to “measure” the temperature of the gas inside the container. The thermocouple really doesn’t care how many degrees of freedom are available.

Comment on Ethics of communicating scientific uncertainty by Pierre-Normand

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captdallas: “Consider a tall container with just one molecule bouncing from bottom to top under gravity. Because of the acceleration of gravity, the molecule will impact the bottom harder than the top. Once that example is “isothermal”, the molecule would be at rest on the bottom. As long as “isothermal” doesn’t mean absolute zero, there will be motion and gravity will have some impact on that motion until all the molecules are closely packed on the bottom.”

Temperature is an ill defined concept for one single molecules. Maybe discussion of this case (gas under gravity in a box) should be postponed to the next open thread. Let me just note that when there is a velocity distribution among many particles, some of them fall down before reaching the top.


Comment on Climate Dialogue: influence of the sun on climate by Richard (rls)

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Milivoje: Thank you. It is very assuring when scientists state the truth. You’ve got my attention.

Comment on Climate Dialogue: influence of the sun on climate by Tonyb

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Fan

Let’s try again. Please answer whether you agree with statement 1 or 2

1. Yes, we know to a few fractions of a degree the global temperatures of oceans back to 1880

2 we do not know the global temperature of oceans back to 1880

Tonyb

Comment on Climate Dialogue: influence of the sun on climate by Frank

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There is a lot we don’t know about past solar variability and its effect on past climate. However, if climate sensitivity for 2XCO2 is about 3.0 degC or greater, I’m not aware of any evidence that suggests that future solar forcing will significant compared to the radiative forcing from a doubling or tripling of CO2 this century. Furthermore, we have no way of knowing whether the sun will modestly increase or decrease future warming. Those who speculate that current hiatus was caused or may be extended by solar variability (or other forms of natural variability such as the AMO) are looking a few small trees in the forest of climate change.

Comment on Climate Dialogue: influence of the sun on climate by Richard (rls)

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Tony,

Fan has seen the borehole curve but is distracted; perhaps it’s the glistening spinning wheel hanging above him.

Richard

Comment on Climate Dialogue: influence of the sun on climate by Matthew R Marler

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Prof Curry, thank you for alerting us to this dialogue. There are many good details and arguments. I’ll quote this one from Mike Lockwood: The key point is that these multiple regression detection/attribution fits all show that the influences are broadly proportional to their estimated radiative forcings, in the case of solar variability that is estimated from TSI observations (as discussed above), which leaves little room for any other solar factor or mechanism. Furthermore, any proposed mechanism must explain all – and I stress all – the data, not just the global means air surface temperature: such constraints include the latitudinal profile (why the Arctic has warmed most), coherent longitudinal variations, the altitude profile (the cooling in the stratosphere), the seasonality (why the warming is greater in winter), the lack of a diurnal variation increase. All these features are well explained by the observed rise in well-mixed greenhouse gases and so to be considered a serious alternative, any proposed mechanism must also explain all these observations.

We have discussed the problems of overfitting, and the problems of estimating one relationship if two variables are correlated (in this case, it would be something that correlated at least monotonically with the TSI changes measured at the Earth surface.) What I liked in that quote was the stress on explaining all of the data. It isn’t sufficient, imho, to “explain” the most recent warming, and to leave all of the previous warmings and coolings unexplained.

If any of the current theories survives the next 25 years or so (this last solar cycle, plus the next 2 solar cylcles) without major (post hoc) revision, I shall be surprised.

One of the interesting themes was the clash of physics-based models versus observation-based models. I am looking forward to the scientific discoveries of the next few decades that will enhance and refine the current physics-based models, and observation-based models, so that their predictions will more accurate and complete over the full set of data, as advocated by Lockwood. If the current knowledge base is not as full of “holes”, “liabilities”, “lacunae”, and “cavities” as I have maintained, then I shall have to eat more than my usual amount of humble pie.

That was a good “climate dialogue”.

Comment on Climate Dialogue: influence of the sun on climate by popesclimatetheory

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The heat from warm river waters draining into the Arctic Ocean is contributing to the melting of Arctic sea ice each summer, a new NASA study finds.

Why do they keep finding new stuff. I thought they believed they already know 97% of everything.

Comment on Climate Dialogue: influence of the sun on climate by Matthew R Marler

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As a follow-on, if the CO2 theory explains the longitudinal distribution of change, and the differential change of the Arctic and Antarctic, and the vertical distribution (lack of Equatorial tropospheric “hot spot”), and apparent pause, could someone direct my attention to the papers that contain all of those explanations?


Comment on Climate Dialogue: influence of the sun on climate by Richard (rls)

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Might there be a need in the future to grow more crops indoors using artificial sunlight, that would require lots of electricity?

Comment on Climate Dialogue: influence of the sun on climate by John

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Hi kim,
“I’m reminded of the flap of a butterfly’s wing…”

My understanding (which could be flawed): The Butterfly Effect was coined by Edward Lorenz relating to the flaws thrown into his weather modeling by his computers flawed math coprocessor. It was from the flawed processing that he found the broader concept. Yet, with the exception of time travel, its largely overwhelmed by natural forces.

The Chaos equation, IMO one of the most significant discoveries of the last century, relates to a normal state change periodically occurring in a physical system. Post-Normal Science is a fair example in a non-physical system but its largely flawed and therefore irrelevant.

The sun is not in a state of chaos — what is your concern?

Comment on Ethics of communicating scientific uncertainty by Pierre-Normand

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captdallas: “P-N, if you don’t like the basic, boring explanation of temperature then use entropy, which container has less entropy?”

It’s not a matter of my not liking your definition of temperature. I am noting that it conflicts with the standard definition that one can find in statistical mechanics textbooks. For the case of ideal gases, or most simple monatomic or diatomic molecules (He, Ar, N2, O2), and normal ranges of temperature and pressure (100K-400K, 0.01atm-100atm), then the relation EKavg = (3/2)kT for kinetic temperature is verified experimentally and kinetic temperature thus defined is a very close match to the thermodynamical definiton as 1/T = dS/dE.

My main point is that your definition of temperature and your claims about total energy content don’t mesh very well. Suppose we start with two identical volumes of gas V at room temperature, one mole each, with total internal energy U for each. We place them both into a big container with a partition between the two volumes. The total energy for the combined system now is 2U, and the volume 2V. We then compress the big container adiabatically back to the original volume V (while the partition stays at the midpoint). This requires some external work dW that is entirely transformed into internal energy dQ. So the internal energy of the gas now is 2U+dQ. We let the gas warm back to the original room temperature. The gain in internal energy thus is lost back to the environment. The internal energy is back to 2U.

However, both Rob and yourself are committed to say that the internal energy is back to U, as it was for each initial volume V before the compression. There is an amount of energy U that has vanished from the universe.

Comment on Ethics of communicating scientific uncertainty by Pierre-Normand

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“We let the gas [cool] back to the original room temperature.”
Sorry.

Comment on Climate Dialogue: influence of the sun on climate by John

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Sorry kim,
I should have said, our sun, our earth, and our solar system are not in a state of chaos…

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