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#1
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The run-away greenhouse is impossible
The conventional explanation of the run-away greenhouse effect,
which produced the conditions we see on Venus today, is that the evaporation of water vapor caused the temperature to rise so high that the atmosphere became unbound. I have seen a journal article that says the temperature would reach 'several thousand degrees' until the surface could 'radiate in the visible'. This is absurd and impossible. In fact I am sure the temperature on Venus has never been significantly hotter than today. First of all, even if the surface did reach such temperatures, it could not 'radiate in the visible' to space, as the H2O atmosphere would be completely opaque at all wavelengths. Even if there were no clouds, it would be nearly opaque in the visible due to Rayleigh scattering. Second, where does the heat come from? No sunlight will reach the surface, so the only source of surface heating is internal heat. On Earth today internal heating of the surface is roughly 1/5,000 of solar heating; on Venus it must be much closer. But regardless of the heat source, convection limits the surface temperature to a value that increases only logarithmically with pressure, and is proportional to the adiabatic lapse rate. In an atmosphere saturated with H2O at high temperatures ( 100 C), the lapse rate is very small; therefore, even though the atmosphere is think, the temperature will surely remain below the critical point of water as long as the atmosphere is mostly water. When, however, the planet has lost most of its water to photo-dissociation, the base of the cloud layer will lift off the ground and the surface temperature rise because of the increase in the lapse rate (the amount of sunlight getting through is irrelevant as long as the atmosphere is in convective equilibrium). This results in the conditions observed on Venus. What happens when the last of the water is lost? The cloud layer then disappears, but the surface temperature won't decrease unless the amount it can now radiate to space exceeds solar input, which seems unlikely unless the CO2 atmosphere is so thick as to be opaque in the visible from Rayleigh scattering (several times Venus). Andrew Usher |
#2
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The run-away greenhouse is impossible
This wasn't supposed to go to soc.men actually.
My point (I didn't quite finish) was that there can be no such thing as a true 'run-away greenhouse', that there can be no abrupt tipping point but only a gradual change. It is nonetheless irreversible, though. Also, this has no effect on projections of man-made global warming, as it can't occur unless solar input is considerably higher than today. Andrew Usher |
#3
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The run-away greenhouse is impossible
Andrew Usher wrote:
This wasn't supposed to go to soc.men actually. My point (I didn't quite finish) was that there can be no such thing as a true 'run-away greenhouse', that there can be no abrupt tipping point but only a gradual change. It is nonetheless irreversible, though. Also, this has no effect on projections of man-made global warming, as it can't occur unless solar input is considerably higher than today. Andrew Usher And according to the Gaia Hypothesis, life on Earth itself will evolve to absorb and subsume any climate conditions that will lead to runaway greenhouse effects. Yousuf Khan |
#4
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The run-away greenhouse is impossible
Yousuf Khan wrote:
And according to the Gaia Hypothesis, life on Earth itself will evolve to absorb and subsume any climate conditions that will lead to runaway greenhouse effects. The planet is not a living organism. Organism live on the planet. Bob Kolker |
#5
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The run-away greenhouse is impossible
On Jun 22, 9:42 pm, "Robert J. Kolker" wrote:
And according to the Gaia Hypothesis, life on Earth itself will evolve to absorb and subsume any climate conditions that will lead to runaway greenhouse effects. The planet is not a living organism. Organism live on the planet. And the way you know this for such a certainty is? Oh that's right. FAITH! I love faith-based science, don't you? I especially love those who have such unquestioned authority that they can simply answer all questions with unshakable assertion that is obviously so authoritative that none dare question it! Love, ya, Bob! |
#6
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The run-away greenhouse is impossible
"Benj" wrote in message
... On Jun 22, 9:42 pm, "Robert J. Kolker" wrote: And according to the Gaia Hypothesis, life on Earth itself will evolve to absorb and subsume any climate conditions that will lead to runaway greenhouse effects. The planet is not a living organism. Organism live on the planet. And the way you know this for such a certainty is? Oh that's right. FAITH! I love faith-based science, don't you? I especially love those who have such unquestioned authority that they can simply answer all questions with unshakable assertion that is obviously so authoritative that none dare question it! Love, ya, Bob! Well, unless you know of some life form that can survive without liquid water and can breath "live" steam, I'd say that Bob is right. The runaway greenhouse predicted for Earth would be the result of solar luminosity increase giving rise to extra CO2 and water vapour, hence greenhouse feedback into yet higher temperatures. By the way, the Gaia Hypothesis is just that, a hypothesis, or conjecture, proposed as an explanation of certain observations in the fossil record. It hasn't reached the status of a theory, yet. -- Mike Dworetsky (Remove pants sp*mbl*ck to reply) |
#7
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The run-away greenhouse is impossible
On Jun 22, 10:53*pm, Benj wrote:
On Jun 22, 9:42 pm, "Robert J. Kolker" wrote: And according to the Gaia Hypothesis, life on Earth itself will evolve to absorb and subsume any climate conditions that will lead to runaway greenhouse effects. The planet is not a living organism. Organism live on the planet. And the way you know this for such a certainty is? *Oh that's right. FAITH! I love faith-based science, don't you? I especially love those who have such unquestioned authority that they can simply answer all questions with unshakable assertion that is obviously so authoritative that none dare question it! Love, ya, Bob! Well, faith based science has its merits by avoiding the brain strain that comes as a reult of serious thinking! Hence, without the brain strain, empty headed believers in faith based science tend live longer than those that actually contribute to the physical sciences, but fortunatly for the human race, don't reproduce very often. This is why we see so many 80 year old Bible thumpers, but not very many historically productive sceintist over the age of roughly 70. Harry C. p.s., On a more serious note, during their college years, most physical science majors burn the midnight oil studying, sometimes pulling all-nighters simply to stay ahead, and in other cases, to pay for their education. I've noticed that this takes years off of one's lifespan. I'm 70, and a vast majority of my physics classmates are already dead. Still, the business and theology majors are still going strong! I have to tell you this: Classical and Theoretical Mechanics courses are the real killers, having seen several physics majors taken away the those nice men in the white lab coats, while still muttering bable about Euler's equations and the nunation and precession of a gyroscope. (I only use Euler as as example, because an equal level of brain strain can result when one thinks about the physical implications of any transform, and it is clearly better for your health to simply accept that these devices work on face value alone. Not ponder them. and why they work. This is how faith simplies life.) Harry C. |
#8
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The run-away greenhouse is impossible
Andrew Usher wrote:
The conventional explanation of the run-away greenhouse effect, which produced the conditions we see on Venus today, is that the evaporation of water vapor caused the temperature to rise so high that the atmosphere became unbound. I have seen a journal article that says the temperature would reach 'several thousand degrees' until the surface could 'radiate in the visible'. This is absurd and impossible. In fact I am sure the temperature on Venus has never been significantly hotter than today. [snip cogent analysis] The following sends the wrong message, doesn't it? It's factual. http://wattsupwiththat.wordpress.com/2008/06/21/a-window-on-water-vapor-and-planetary-temperature-part-2/ Sunspots and such, Graphics ======== http://upload.wikimedia.org/wikipedia/commons/2/28/Sunspot_Numbers.png The most recent minimum, to the right, has averaged about 10 sunspots/month. http://www.dxlc.com/solar/images/solar.gif local solar flux is dropping http://www.skepticalscience.com/images/tsi_composite.gif local solar flux is dropping http://www.swpc.noaa.gov/SolarCycle/Ap.gif local solar flux is dropping to 10-year lows http://www.swpc.noaa.gov/SolarCycle/sunspot.gif projected sunspot number. All we need do is wait and see. The third unmentioned red curve would be more interesting - stays flat. COMMENTARY ========== Global Cooling is nothing new. Click on graphics to enlarge. http://smarteconomy.typepad.com/smart_economy/2006/09/global_warming_.html http://www.newrivervalleynews.com/content/view/12742/261/ http://www.climatescienceinternational.org/index.php?option=com_content&task=view&id=31&Itemi d=1 http://ff.org/centers/csspp/library/co2weekly/20060920/20060920_13.html layman reference http://www.sciencedaily.com/releases/2004/06/040602061025.htm slightly better http://www.grisda.org/origins/10051.htm data Weather is always extreme compared to climate. One can play the GLOBAL WARNING game with anything, earthquakes to http://thepoorman.net/2008/06/18/gregg-easterbrook-is-wait-for-it-an-idiot/ Proximity is not causality. More hurricanes than any other time in history were predicted post-Katrina! What does the highly anomalous *absence* of Caribbean hurricanes portend? Extreme hurricane disasters! Eventually a pulse will appear. So? -- Uncle Al http://www.mazepath.com/uncleal/ (Toxic URL! Unsafe for children and most mammals) http://www.mazepath.com/uncleal/lajos.htm#a2 |
#9
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The run-away greenhouse is impossible
On Jun 22, 10:53*pm, Benj wrote:
On Jun 22, 9:42 pm, "Robert J. Kolker" wrote: And according to the Gaia Hypothesis, life on Earth itself will evolve to absorb and subsume any climate conditions that will lead to runaway greenhouse effects. The planet is not a living organism. Organism live on the planet. And the way you know this for such a certainty is? *Oh that's right. FAITH! Science does not deal in "know this for such a certainty." Science deals in valid theories that make predictions and can be falsified. The "Gaia hypothesis" isn't such a thing. The "Gaia hypothesis" is bad poetry. We know that the planet isn't alive because we go out and observe it and it does not have any of the properties of a living thing. I love faith-based science, don't you? No, I don't. And the "Gaia hypothesis" is one such chunk of trash that we really would be better off putting in the dustbin. It can keep company with alchemy and phlogisten. I especially love those who have such unquestioned authority that they can simply answer all questions with unshakable assertion that is obviously so authoritative that none dare question it! Love, ya, Bob! Um. Where do you see these unshakable assertions? Other than in the pronouncements of the Gaia enthusiasts that is. Socks |
#10
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The run-away greenhouse is impossible
On Jun 22, 9:42*pm, "Robert J. Kolker" wrote:
Yousuf Khan wrote: And according to the Gaia Hypothesis, life on Earth itself will evolve to absorb and subsume any climate conditions that will lead to runaway greenhouse effects. The planet is not a living organism. Organism live on the planet. Not that he said that... I read Yousef's comment as discussing the effect of "life on Earth" collectively. not that the earth itself is alive, nor that he personally endorses the Gaia 'Hypothesis' (really a New-Age neo- religion). The consequence of non-equilibrium thermodynamics (see Prigogene, for example) is that 'dissipative systems' (such as 'organic life') that absorb absorb energy and reduce entropy are almost inevitable wherever a system has a net energy influx, a solvent which can affect the constituents of the system, and a potential for a phase transition in the solvent. The temperature and phase changes will differentiate and segregate the constituents, producing 'organized' structures and reducing entropy locally. Bob Kolker Tom Davidson Richmond, VA |
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