By Steve Goddard
The classic cure for hyperventilation is to put a paper bag over your head, which increases your CO2 levels and reduces the amount of Oxygen in your bloodstream. Global warmers have been hyperventilating over CO2 on Venus, ever since Carl Sagan made popular the idea of a runaway greenhouse effect. That was when he wasn’t warning about nuclear winter.
Sagan said that marijuana helped him write some of his books.
I bought off on the “runaway greenhouse” idea on Venus for several decades (without smoking pot) and only very recently have come to understand that the theory is beyond absurd. I explain below.
The first problem is that the surface of Venus receives no direct sunshine. The Venusian atmosphere is full of dense, high clouds “30–40 km thick with bases at 30–35 km altitude.” The way a greenhouse effect works is by shortwave radiation warming the ground, and greenhouse gases impeding the return of long wave radiation to space. Since there is very little sunshine reaching below 30km on Venus, it does not warm the surface much. This is further evidenced by the fact that there is almost no difference in temperature on Venus between day and night. It is just as hot during their very long (1400 hours) nights, so the 485C temperatures can not be due to solar heating and a resultant greenhouse effect. The days on Venus are dim and the nights are pitch black.
The next problem is that the albedo of Venus is very high, due to the 100% cloud cover. At least 65% of the sunshine received by Venus is immediately reflected back into space. Even the upper atmosphere doesn’t receive a lot of sunshine. The top of Venus’ atmosphere receives 1.9 times as much solar radiation as earth, but the albedo is more than double earth’s – so the net effect is that Venus’ upper atmosphere receives a lower TSI than earth.
The third problem is that Venus has almost no water vapor in the atmosphere. The concentration of water vapor is about one thousand times greater on earth.
Composition of Venus Atmosphere
0.965 CO2
0.035 N2
0.00015 SO2
0.00007 AR
0.00002 H2O
Water vapor is a much more important greenhouse gas than CO2, because it absorbs a wider spectrum of infrared light – as can be seen in the image below.
http://www.globalwarmingart.com/images/7/7c/Atmospheric_Transmission.png
The effects of increasing CO2 decay logarithmically. Each doubling of CO2 increases temperatures by 2-3C. So if earth went from .04% CO2 to 100% CO2, it would raise temperatures by less than 25-36C.
Even worse, if earth’s atmosphere had almost no water (like Venus) temperatures would be much colder – like the Arctic. The excess CO2 does not begin to compensate for the lack of H2O. Water vapour accounts for 70-95% of the greenhouse effect on earth. The whole basis of the CAGW argument is that H2O feedback will overwhelm the system, yet Venus has essentially no H2O to feed back. CAGW proponents are talking out of both sides of their mouth.
So why is Venus hot? Because it has an extremely high atmospheric pressure. The atmospheric pressure on Venus is 92X greater than earth. Temperatures in Earth’s atmosphere warm over 80C going from 20 kPa (altitude 15km) to 100 kPa (sea level.) That is why mountains are much colder than the deserts which lie at their base.
The atmospheric pressure on Venus is greater than 9,000 kPa. At those pressures, we would expect Venus to be very hot. Much, much hotter than Death Valley.
http://en.wikipedia.org/wiki/File:Emagram.GIF
Wikipedia typifies the illogical “runaway greenhouse” argument with this statement.
Without the greenhouse effect caused by the carbon dioxide in the atmosphere, the temperature at the surface of Venus would be quite similar to that on Earth.
No it wouldn’t. 9000 kPa atmospheric pressure would occur on earth at an altitude many miles below sea level. No such place exists, but if it did – it would be extremely hot, like Venus. A back of the envelope estimate – temperatures on earth increase by about 80C going from 20 to 100 kPa, so at 9,000 kPa we would expect temperatures to be in the ballpark of :
20C + ln(9000/(100-20)) *80C = 400C
This is very close to what we see on Venus. The high temperatures there can be almost completely explained by atmospheric pressure – not composition. If 90% of the CO2 in Venus atmosphere was replaced by Nitrogen, it would change temperatures there by only a few tens of degrees.
How did such bad science become “common knowledge?” The greenhouse effect can not be the cause of the high temperatures on Venus. “Group Think” at it’s worst, and I am embarrassed to admit that I blindly accepted it for decades.
Blame CO2 first – ask questions later.
=============================
UPDATE: Lubos Motl has written an essay and analysis that broadly agrees with this post. See it here
Bill Illis Reur May 6, 2010 at 5:22 pm:
And, in response:
JAE Reur May 6, 2010 at 6:43 pm:
I strongly agree with these sentiments. It is beyond me that in extremely complex systems some people try to pick out a single cause!
There have been a host of comments here asserting that the GH effect is THE cause of the high T. However, I don’t think that a single such asserter has commented on an important issue in Steven’s article, which is the extremely long day together with claimed uniformity of diurnal T. NASA gives the diurnal temperature difference as zero, last updated 2005. The ESA reiterated this in 2006.
The puzzle is of course that if there is a significant GH effect, then how does it work during the months of darkness!
According to the ESA, the dynamics of the atmosphere are really weird, (at least with the scant data available), and not well understood. It seems to me that these strange dynamics may somehow “mix” the GH heating across to the dark side, but it also suggests to me that the GH effect is relatively minor.
Here is an interesting extract speculation
from an ESA article:
“…The ‘temperature inversion’, as the layer of warm air is called, was detected in several stellar occultations performed on the night-time side of the planet. The only thing that can heat the atmosphere here is when pockets of gas sink back down into the denser atmosphere. The increased air pressure squeezes the pockets, raising the temperature of the gas inside (similar to what happens when you activate a bicycle pump)…”
Here is an extract concerning winds from another ESA article:
The lower atmosphere of Venus has a dramatic and peculiar behaviour. At the level of the cloud tops, the atmosphere rotates at a formidable velocity, with wind speeds up to 360 kilometres per hour. [Elsewhere; four days to circumnavigate]
The speed of the winds then progressively decreases to almost zero at the planet surface, where it becomes a gentle breeze, only able to raise dust. What mechanisms cause this ‘zonal super-rotation’?
Furthermore, two enormous vortices, with very complex shapes and behaviours, rotate vertically over the poles, recycling the atmosphere downwards. The vortex at the north pole, the only one previously observed in some detail, has a peculiar double ‘eye’ shape, surrounded by a collar of cool air. It completes a full rotation in only three Earth days.
How are the super-rotation and the polar vortices linked? How does the global atmospheric circulation on Venus work? No model is able to simulate so far the dynamics of the atmosphere of Venus as too few data are available.
Steven 9:06. No you are misquoting me. I claim that the green house effect on Venus is real. In fact it very significantly blocks (almost eliminates) radiation from the surface of the planet to space. Given that, the heat must escape to the top of the atmosphere (where it can be radiated) by conduction and convection. Once you rely on that process the thickness of the atmosphere does matter. Vincent 10:40 has noted this.
Alan McIntire at 6:54 Alan I would very much like to post some articles on wattsupwtihthat but I do not know of any way of emailing them to Antony. I did request an email conact address via a message in the tips and notes section of the website but got no reply. There are some interesting issues. It seems to me that some of the Nimbus data is in conflict with “established wisdom”. Two issues in particular, one that the emissivity of ice and snow in the thermal infrared is close to1 and secondly that the stratosphere is well mixed. These may sound esoteric and of limited interest but infact they have serious impact on the AGW issues. I admit I could be wrong but it would be very interesting to debate this on the blog. The thermal infra red emissivity issue is particularly interesting because if true it means that soot in ice covered regions leads to negative feedback not positive feeedback and will cool the region. Also by the way the same Nimbus data shows extremely clearly that the direct impact of the green house effect is to cool the poles not warm them.
stevengoddard says:
May 7, 2010 at 6:39 am
I saw it up at the top. I didn’t bother to click on it to read it better, it was just a blank Skew-T chart. You would have saved a lot of arguing if you had used just a real sounding from Venus like I linked to above and six weeks ago. Being a Terran Skew-T chart, it has wet adiabats cluttering up what you want to show, and all the scales simply don’t apply to Venus without more scaling and redrawing than I can do off-hand.
If you expected people unfamiliar with atmospheric lapse rates to glance at the graph paper and understand how it applies to Earth, you’re sadly mistaken. The introduction to Skew-T plotting http://airsnrt.jpl.nasa.gov/SkewT_info.html needs 9 pages to print and much of that doesn’t even apply to Venus. Besides the lack of water vapor, I suspect the atmosphere is very well mixed and inversions, CAPE, and all that good Terran meteorology stuff on the graph paper just muddies the issue.
You description of the Venusian lapse rate just didn’t work. Apparently it’s too late to fix it now, attempts get lost in the 373 comments so far.
Is this directed to me? I wouldn’t call it obvious – we frequently have winter mornings in New Hampshire where the top of Mt Washington (6288′) is warmer than the valley. However, those conditions likely don’t apply on Venus. Perhaps they do given the long nights, but in daytime conditions once the inversion dissipates/evaporates/whatever it does when the surface warms up then air mixes up and down as easily as it moves from side to side and follows the dry adiabatic lapse rate on the chart up to the clouds and the wet adiabatic lapse rate up to the top of the mixed air.
Guess I’ll go see how Lubos did with his article.
michael hammer
No one is misquoting you. You attributed the high temperatures on Venus to an effect caused by high pressure. Your words:
Everything else kept the same, without the high pressure, Venus would be cooler than earth due to the lack of water vapour.
******
stevengoddard says:
May 7, 2010 at 2:07 pm
beng
The top of the Grand Canyon receives just as much solar radiation as the bottom of the Grand Canyon, yet it tends to be 20-30 degrees F cooler.
How does that fit into your theory “The atmosphere is mostly heated at the bottom by the warm, irradiated surface…That’s why it’s warmer down there, not because of pressure. “
******
It’s a good question. I think I’m right about this, but not sure how to explain it, since I’m just an old power-plant engineer.
I like to think in terms of insulation. Qualitatively, there’s alot of similarity w/GHG effects. In a layer of insulation, there’s a similar “temp lapse rate” across its thickness from the hot/cold pipe temps to ambient temps. This is why falling stratospheric temps could suggest increasing GHG effects — just like adding more insulation on a hot pipe makes the outside insulation surface feel less & less hot, gradually approaching ambient temp as more insulation is added.
In this simplistic (but qualitatively correct) view, the top of Grand Canyon has less insulating atmosphere above it (including GHGs), and so loses more heat via IR radiation to the sky than lower elevations (notice how the sky gets darker blue as you gain elevation, eventually becoming black). The average temp is less, despite the same solar input.
Ric,
Lapse rates on Venus (10.468 K/km) are very similar to Earth (9.760 K/km.)
http://atmos.nmsu.edu/education_and_outreach/encyclopedia/adiabatic_lapse_rate.htm
I’m sorry that you are confused.
Phil.
Venus and Earth have very similar energy budgets, which are set by TSI and albedo at the TOA.
The difference is that Venus has a very thick (high pressure) atmosphere. If you dug an open pit 30 miles deep in the earth, the air temperature would be comparable to Venus.
Re: stevengoddard says:
May 7, 2010 at 4:29 pm
“What would happen to atmospheric pressure if the sun turned off?
PV = nRT
If T dropped to zero, then P would also drop to zero. It is the sun which provides the energy that keeps the molecules moving, and keeps the pressure up.”
1) This ignores all heat from a planet’s core and any subsequent tectonics and volcanism that may result, and it in addition also ignores energy released due to radioactive decay.
2) Your statement is actually backwards in a practical sense. In most planetary atmospheres, higher temperature = lower pressure because the atmosphere is free to expand.
3) If what you said were true in a blanket sense, then the moon Titan, which is nearly 10 times farther away from the Sun than the Earth, should have almost no atmosphere. Instead, Titan has an atmospheric pressure identical to Earth. It is the cold that keeps the pressure up on Titan, not the heat, because the atmosphere has contracted.
Every planetary environment must be specifically considered because each is unique from the others.
In Canberra, I live at 800m and due to cool air pooling at night it will be 2-3degC warmer that the valley/ airport where the temperature readings are taken at
500m. Day temperatures are similar.
To discuss cooler temperatures with altitude, I might start with my concern about the difference between reading air and radiative readings.
What are you reading with radiative ? reflected energy from a radiative body, so on the moon is there any difference between lunar valleys and peaks? I think not, a hot rock heated by the sun is really the same in a valley or on a mountain top.
On a rocky planet with an atmosphere there is, in still air, the adiabatic lapse rate.
But what is being measured in a temperature reading of atmosphere? molecular collisions with a sensor, given that the the sensor is cooler than surrounding air when the temperature is rising and the reverse applies in cooling temperatures. In cooling the sensor is back radiating the energy received by air molecular collisions, so it lags slightly the true reading. Now at ground level the air is denser and there will be more collisions and limited sensor back radiation ‘cooling’, but at altitude with less dense air there are less collisions and more chance of sensor back radiation. So the temperature at altitude is lower as the sensor has greater freedom to give back collision energy. At altitude the collisions would also be fewer and less energetic. Perhaps to measure correctly at altitude we need to surround the sensor in a pressurised box matching the pressure at ground level and then compare readings. The ‘collisions’ would be similar and you would be measuring the energy level difference which would be a more accurate measure of temperature difference, assuming still air.
Really the intimate contact of a free flowing liquid with a sensor is the most accurate indication of the temperature of the fluid. Anything measured in air, thick (but not liquid) or rarefied, is influenced by the molecular collision rate and will give a spurious result.
Is this a reasonable argument?
michael hammer says:
May 7, 2010 at 5:02 pm
My bible on these matters, “The Climate Near The Ground” (first published back in the day when people actually measured things) gives the emissivity of fresh snow in the 9-12 micron region as 0.986.
There’s an excellent library of emissivity values here. It says inter alia:
Note that these are measured values from actual samples.
Emissivity of carbon seems to range from 0.8 to 0.95, depending on the exact form. The main effect of black carbon on snow/ice is the huge difference between the albedo of the two. Toss some wood ashes out on the snow, wait a day or so, and you’ll see what I mean.
We now return you to your regularly scheduled programming … Venus.
To me, the key to the Venus temperature is the clouds. High clouds surround the planet. When you have that, most of the IR will be radiated from up high, and the lapse rate will guarantee a warmer surface. How much warmer? Depends on the elevation of the clouds, which for Venus is very high (on the order of 75 km). Given high IR absorbing clouds, the composition of the lower atmosphere is not so important.
I do thermodynamic calculations almost every day- engine cycles (often various flavors of Brayton and Rankine cycle), heat transfer in regeneratively cooled rocket engines, things of that sort. I use the PV=nRT relation routinely, and I see a lot misunderstanding of it in this post and these comments. I’ll try to help, please bear with me.
For instance, turning off the sun and cooling the Earth’s atmosphere would NOT change the sea level pressure… only the scale height would change, as the density increased with lower temperatures. Pressures at higher altitudes would drop proportional to the altitude and the temperature ratio, as the colder, denser atmosphere “fell” to lower altitudes. Finally, as the surface temperature approached 90K, the boiling point of LOX, the air would start to rain out, and finally the sea level pressure would drop. On a uniform spherical earth, the pressure at the bottom of the liquid air ocean would still be 101 kilopascals, with the same 10 metric tons of air on top of each square meter.
Back to Venus, though. Just below the cloud tops, the atmosphere is effectively opaque, scattering or absorbing almost all sunlight so that very little reaches the surface to heat it. The crucial altitude is the one where the air is opaque in thermal IR wavelengths- at around 60-70 km this is where the radiation budget balances at about 240K. Below this altitude, absorption of solar heat drives convective heat transfer, and the temperature gradient is can be no greater than the dry adiabatic lapse rate… which is really just the ideal gas law with a geopotential term added .
So you see, the temperature at the top of the troposphere is similar to that on Earth, but there’s a lot more air below that point, mostly at the dry lapse rate. Why at that rate? The _conduction_ through any air is very low, so if there is even a tiny heat flux toward the surface, the lower layers will heat up until the gradient reaches the convective limit (the dry lapse rate). This is what makes a troposphere a troposphere, and for almost any heat flux across a large range, will display the dry adiabatic lapse rate unless there is enough of a condensible component to drop it to the wet adiabatic lapse rate. On Venus, that species is sulfuric acid, oh joy, and sure enough, the lapse rate is diminished in the cloud layers. http://en.wikipedia.org/wiki/Venus%27_atmosphere
So yes, on Venus as on Earth, CO2 is not the critical component controlling the temperatures, it is the cloud- and rain-making component that matters. On Earth, water, on Venus, sulfuric acid.
Keith Minto,
This JPL publication has a good graph on page 12 showing the inversion effect you see at night in Canberra.
http://trs-new.jpl.nasa.gov/dspace/bitstream/2014/13139/1/01-1749.pdf
Below 2,000 feet, there is a temperature inversion. Otherwise, temperatures decrease linearly about 10C per 4,000 ft elevation.
astrowright
Heat escaping from the interior of the Earth is very small compared to heat received from the Sun.
Higher temperature and pressure almost always go together. Mountains have cold, low pressure air. Lower elevations have warm, high pressure air. That is why people ski at high elevations where the air is thin, and why people in Colorado take vacations in Hawaii.
michael hammer says:
May 7, 2010 at 5:02 pm
> Alan McIntire at 6:54 Alan I would very much like to post some articles on wattsupwtihthat but I do not know of any way of emailing them to Antony.
Anthony’s official “public” Email address is info (at sign) surfacestations.org,
http://www.surfacestations.org/contact.htm
I have another, that I think is the “good” one that I’ve come across twice, but Anthony hasn’t given it to me, so I won’t share it and haven’t used it. I expect to see him in Chicago in a couple weeks.
BTW, thanks for your post on spectral broadening, etc. I’ve been meaning to hunt down more about that for the last year or two. I have a question – once a CO2 molecule absorbs a photon, how long does it take before it reradiates it, and how long does it take before it bangs into an air molecule and transfers energy in the collision? Both in high altitude (say 10 mb) and low (1000 mb) conditions.
Doug Jones
Molecules would stop moving at absolute zero, so there would be no pressure. Pressure is caused by movement of molecules.
Of course, you can’t have gases as you approach absolute zero.
This discussion of Venus and the relationship between atmospheric pressure and planetary surface/atmosphere temperatures has prompted me to describe and seek solutions to three “simplified planetary-like” atmospheric scenarios. The solutions to these scenarios may provide insight into the thermal effects of atmospheric greenhouse gases on planets devoid of water. Specifically, if solutions can be generated, we should at least start to quantitatively understand the phenomenon of Co2 IR “energy capture”–a term often used, but not well understood, in the AGW discussion.
All three scenarios use the same model of the planetary surface, but they differ in their atmosphere models. For each model, I seek quantitative characterizations of the temperature/pressure properties of the models. I don’t have the knowledge to provide answers to those questions; but given the responses to Mr. Goddard’s blog, I thought readers of this blog might be able to provide those answers.
Planetary Surface Model:
Suppose in the vacuum of space and “infinitely far removed” from all other celestial bodies, we have a thin spherical “shell” that from every perspective possesses spherical symmetry about the center of the sphere. Assume (a) the shell mass is equal to the mass of the Earth, (b) the shell outside radius is the average of the Earth’s polar and equatorial radii, (c) the shell thickness is small compared to its radius, (d) the shell is diathermic (i.e., a perfect conductor of heat) and (e) when in the presence of a vacuum, both the inner and outer shell surfaces are “black body” radiators. The shell center of mass is at rest with respect to inertial space, and the shell is NOT rotating. At time zero, the temperature of the shell is below the freezing points of carbon dioxide (CO2), Oxygen (O2) and Nitrogen (O2). Within the walls of the shell we have an energy source that generates heat at a rate such that if the vacuum of space exists everywhere outside the shell, when the outgoing rate of black body radiated energy equals the rate of internal energy generation, the surface of the shell will be at a uniform temperature of 290 K.
First Atmosphere Model:
Over the outside surface of the shell we symmetrically distribute (a) a mass of Oxygen (O2) equal to the mass of Oxygen in the Earth’s atmosphere, and (b) a mass of Nitrogen (N2) equal to the mass of Nitrogen in the Earth’s atmosphere. All masses are distributed at the temperature of the shell surface at time zero–i.e., they are distributed as solids. We observe the shell and its “atmosphere” as time progresses. The heat generated in the shell walls will warm the shell surface, first melting and then vaporizing the Oxygen and Nitrogen. Heat will be transfered away from the shell surface via both conduction and radiation. Symmetry arguments preclude heat transfer via convection. The shell surface, the Oxygen and the Nitrogen will all conduct and radiate heat. Portions of that radiated energy will be absorbed by the shell surface and the atmospheric gases, and portions of the radiated energy will “escape” into space. When the total energy per unit time “escaping” into space is equal to the rate at which energy is generated within the walls of the shell, the shell/atmosphere system will have reached steady state and macroscopic changes will cease. Steady-state conditions will include (a) a temperature for the surface of the shell, (b) a temperature profile as a function of distance above the surface of the shell, and (c) partial pressure profiles for Oxygen and Nitrogen as a function of distance above the surface of the shell.
Second Atmosphere Model
Same as the First Atmosphere Model at time zero except that along with Oxygen and Nitrogen we symmetrically distribute a mass of Carbon Dioxide (CO2) equal to the mass of CO2 in the Earth’s atmosphere. As with the First Atmosphere Model, we are interested in the steady-state (a) surface temperature, (b) temperature profile as a function of distance above the shell surface, and (c) partial pressure profiles as a function of distance above the shell surface.
Third Atmosphere Model
Same as the Second Atmosphere Model at time zero except that we symmetrically distribute an additional mass of CO2 equal to 1% of the CO2 mass of the Second Atmosphere Model. As with the First and Second Atmosphere Models, we are interested in the steady-state (a) surface temperature, (b) temperature profile as a function of distance above the shell surface, and (c) partial pressure profiles as a function of distance above the shell surface.
For the above three scenarios, quantitative solutions for the shell surface temperature and atmospheric temperature profiles should help us better understand the phenomenon of “CO2 IR energy trapping”.
Ric Werme says:
May 7, 2010 at 7:41 pm
I have a question – once a CO2 molecule absorbs a photon, how long does it take before it reradiates it, and how long does it take before it bangs into an air molecule and transfers energy in the collision? Both in high altitude (say 10 mb) and low (1000 mb) conditions.
Collision rates are approximately 10/nsec at atmospheric pressure, it will take a number of collisions to deactivate the excited state. The mean radiation lifetime for CO2 is orders of magnitudes higher.
Nick Stokes,
“No, it wouldn’t, not without a greenhouse effect. A surface at 700K emits about 12,000 W/m2. Incoming sunlight, averaged over surface area, on Venus is about 400 W/m2. If the atmosphere is transparent to thermal IR, that 12,000 W/m2 would just go out to space and sunlight couldn’t possibly balance it. The surface would cool.
This is based on assumptions that you and other scientists have made about the origin of Venus. IF Venus is young the internal heat of the planet will easily keep the surface at high temps with no help from anything for a time. Please prove your assumption that Venus is about 4 billion years old or that it did not have a rather large collision in the recent past that raised the temp and resurfaced it.
“What does balance it, of course, is thermal IR emitted from the atmosphere itself. But that can only happen with some GHG effect.
The adiabatic transport effect can explain a temperature difference. But it can’t provide that source of radiant heat. All it means is that TOA would be correspondingly colder.
“The way a greenhouse effect works is by shortwave radiation warming the ground, and greenhouse gases impeding the return of long wave radiation to space.”
It doesn’t have to involve the ground. It only requires that heat passes through a layer of gas at a frequency to which the gas is relatively transparent, and is part-blocked from returning at lower thermal IR frequency. It doesn’t matter whether the absorption and reemission happens at the ground or at a lower level of the atmosphere.”
Nick, Venus emits more energy than it receives in SW. Your argument is a non-sequitur.
“So to qualify my earlier remark – you can’t have 700K on the surface with an IR-transparent atmosphere. You could get a high temperature from cloud blocking plus adiabat, even without selective IR absorption. You can also get it from a greenhouse effect, and there’s lots of GHG for that. Both effects seem to be at work here.”
CO2 only covers very narrow bands even here on earth. What other GHG’s are there to cover all the rest of the bandwidth of IR?? Do you think the little OH found in the atmosphere on Venus will replace the water vapor function seen here on earth?? By the way, why do you think there is ANY water vapor on Venus again?? Got any explanation for the continuous hurricane force winds, the radar reflectivity of the peaks, the interesting anomalies at both poles?? Why do you argue from IGNORANCE??
“Beng, I think you and Steven each have half the story there. Some people are saying that somehow pressure causes high temperature. That’s wrong – a cylinder of compressed oxygen will generally be at ambient temperature.”
Only AFTER it has radiated the heat due to compression to the environment. Now, if the cylinder is partially filled with liquid air, THEN it might never be at higher than local temps. Of course, the heat from liquifying the air was radiated elsewhere.
Nick, for a guy who can pull out formulas when it suits your argument, you write some awfully stupid things at times!! When are you going to grow a pair and admit you are trying to shore up CRAP!!!
So when I was a child, and before years of engineering education my childhood heros were: Asimov, Feynman, and Tesla.
The people I thought were the biggest idiots? Sagan, Hawking, and Ford.
I still stand by those choices I made as a child.
stevengoddard says:
May 7, 2010 at 7:41 pm
Doug Jones
Pressure is merely force per unit area and comes from more than just gases.
I used to work in an old woolen mill converted to building computer systems. There were a number of signs around listing the maximum floor loading in pounds per square foot, typically 50 lbs/ft^2. Surprisingly, none of us ever fell through the floor, even if we stood on one foot, but I digress.
So, if we simply cooled our shoes to 0.0 Kelvins we would have been even safer!
Cool!
…can we all at least agree that the likelihood of Earth experiencing a Venus-like runaway greenhouse effect is essentially zero?
Well, unless Earth develops clouds of sulfuric acid and a surface pressure of 93 bar, anyway!
Ric Werme
Unless you are gas suspended in the atmosphere, the analogy isn’t going to work. The pressure from your shoes to the floor is caused by gravity. Gas pressure on the other hand is caused by movement of molecules.
kuhnkat
Not much SW radiation is absorbed by the atmosphere, particularly the lower atmosphere. Almost all of it that comes through the clouds warms the ground.
http://www.globalwarmingart.com/images/7/7c/Atmospheric_Transmission.png
Once pressure has stabilised it doesn’t create heat, so how can this be warming the atmosphere of Venus?
Robert of Ottawa
Look again. The second graph has Venus’s pressure = Earth’s sea level pressure at 49.5km and at that altitude, the first graph has temperature at about 350K (76C).
There are several fundamental flaws in this whole argument. One is that PV=nRT applies in a closed system. If the planet is able to radiate to space, you don’t have a closed system, so the temperature will drop until energy in = energy out. Also, you cannot equate conditions on Earth to those on Venus with a much higher CO_2 concentration. The logarithmic relationship between CO_2 concentration and warming breaks down at around 10%. Pressure broadening is well understood by planetary atmosphere scientists, and the very high temperatures of Venus cannot be explained without it. Mars with a very different scenario, very low pressure, is also accurately modelled by the same theory. As are Earth’s major climate swings, including extremes such as a snowball earth.
If you have a better theory, work it through in detail and let’s see it. This is all a little too hand-wavy for my liking, not least since it doesn’t work through the physics or explain how it fits observations better than the existing theory. Wishful thinking and putting down the aspects of a theory you disagree with to pot smoking is a pretty sloppy way of doing science to say the least.