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The runaway greenhouse effect on Venus

What the science says...

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Venus very likely underwent a runaway or ‘moist’ greenhouse phase earlier in its history, and today is kept hot by a dense CO2 atmosphere.

Climate Myth...

Venus doesn't have a runaway greenhouse effect

"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." (Steve Goddard, WUWT)

At a glance

Earth: we take its existence for granted. But when one looks at its early evolution, from around 4.56 billion years ago, the fact that we are here at all starts to look miraculous.

Over billions of years, stars are born and then die. Our modern telescopes can observe such processes across the cosmos. So we have a reasonable idea of what happened when our own Solar System was young. It started out as a vast spinning disc of dust with the young Sun at its centre. What happened next?

Readers who look up a lot at night will be familiar with shooting stars. These are small remnants of the early Solar System, drawn towards Earth's surface by our planet's gravitational pull. Billions of years ago, the same thing happened but on an absolutely massive scale. Fledgeling protoplanets attracted more and more matter to themselves. Lots of them collided. Eventually out of all this violent chaos, a few winners emerged, making up the Solar System as we now know it.

The early Solar system was also extremely hot. Even more heat was generated during the near-constant collisions and through the super-abundance of fiercely radioactive isotopes. Protoplanets became so hot that they went through a completely molten stage, during which heavy elements such as iron sank down through gravity, towards the centre. That's how their cores formed. At the same time, the displaced lighter material rose, to form their silicate mantles. This dramatic process, that affected all juvenile rocky planets, is known as planetary differentiation.

Earth and Venus are the two largest rocky planets. But at some point after differentiation and solidification of their magma-oceans, their paths diverged. Earth ended up becoming habitable to life, but Venus turned into a hellscape. What happened?

There's a lot we don't know about Venus. But what we do know is that the surface temperature is hot enough to melt lead, at 477 °C (890 °F). Atmospheric pressure is akin to that found on Earth - but over a kilometre down in the oceans. The orbit of Venus may be closer to the Sun but a lot of the sunlight bathing the planet is reflected by the thick and permanent cloud cover. Several attempts to land probes on the surface have seen the craft expire during descent or only a short while (~2 hours max.) after landing.

Nevertheless, radar has been used to map the features of the planetary surface and analyses have been made of the Venusian atmosphere. The latter is almost all carbon dioxide, with a bit of nitrogen. Sulphuric acid droplets make up the clouds. Many hypotheses have been put forward for the evidently different evolution of Venus, but the critical bit - testing them - requires fieldwork under the most difficult conditions in the inner Solar System.

One leading hypothesis is that early on, Venus experienced a runaway water vapour-based greenhouse effect. Water vapour built up in the atmosphere and temperatures rose and rose until a point was reached where the oceans had evaporated. In the upper atmosphere, the water (H2O) molecules were split by exposure to high-energy ultraviolet light and the light hydrogen component escaped to space.

With that progressive loss of water, most processes that consume CO2 would eventually grind to a halt, unlike on Earth. Carbon dioxide released by volcanic activity would then simply accumulate in the Venusian atmosphere over billions of years, creating the stable but unfriendly conditions we see there today.

Earth instead managed to hang onto its water, to become the benign, life-supporting place where we live. We should be grateful!

Please use this form to provide feedback about this new "At a glance" section. Read a more technical version below or dig deeper via the tabs above!

Further details

Venus may have experienced a runaway greenhouse effect in the geological past. To use the term 'runaway' is to refer to a highly specific process when discussed by planetary scientists. Simply having a very hot, high-CO2 atmosphere is not it. So let's start with a tutorial on Venus at the present day.

Venus’ orbit is much closer to the sun, which means it receives almost twice the solar radiation at the top of its atmosphere than Earth. Venus also has a very high albedo which ends up over-compensating for the closer distance to the sun. The result is that less than 10% of that incident solar radiation reaches the surface. High albedo can be attributed to sulphur-bearing compounds, along with minor water vapour (around 20 ppm). These substances form globally encircling sulphuric acid-dominated cloud decks (fig. 1). Venus’ atmosphere also has a surface pressure of around 92 bars (or if you like, 92,000 millibars), equivalent to what you’d feel on Earth beneath more than a kilometre of ocean.

Venus in its shroud of clouds.

Fig. 1: Venus in its shroud of clouds - a false colour composite created by combining images taken using orange and ultraviolet spectral filters on the Mariner 10 spacecraft's imaging camera.The images used to create this view were acquired in 1974; the RH one has been enhanced to bring out texture and colour. Image: NASA.

Observations of the water vapour content in the Venusian atmosphere show a high heavy to light hydrogen isotopic ratio (D/H). This is best interpreted as the product of a preferential light hydrogen escape to space: deuterium escapes less easily. Venus is considered to have had at least 100 times its current water content in the past (e.g. Selsis et al. 2007 and references therein).

The greenhouse effect on Venus today is primarily caused by CO2, although water vapour and SO2 are important as well. Since most of the radiation that makes its way out to space comes from only the very topmost parts of the atmosphere, it can look as cold as Mars in infra-red (IR) imagery. In reality, the surface of Venus (Fig. 2) is even hotter than the dayside of Mercury, at a deadly 477 °C (890 °F).

Like Earth, the Venusian clouds also generate a greenhouse effect. However, they are poor IR absorbers and emitters compared to water clouds. The sulfuric acid droplets forming the clouds can also scatter IR radiation back to the surface, producing another form of the greenhouse effect in that way. In the dense Venusian CO2-rich atmosphere, there are IR-handling processes at work that are unimportant on modern Earth.

The Soviet Union's Venera 14 probe.

Fig. 2: The Soviet Union's Venera 14 probe captured two colour panoramas of Venus's surface in 1982. This panorama came from the rear camera. Image: Russian Academy of Sciences. More images can be seen at:

How to get a Runaway?

To get a true runaway greenhouse effect on Venus, you need a combination of solar radiation and the presence of a greenhouse gas. That gas has two key requirements. It must be condensable and it needs to be in equilibrium with its surface reservoir. In addition, its concentration must increase with temperature, as explained by the Clausius-Clapeyron relation. For Venus to enter a runaway greenhouse state, the greenhouse gas of interest is water vapour, plus its liquid reservoir, the water making up the oceans.

The greenhouse effect on any planet involves impeding the flux of outwards longwave radiation to space. Water vapour is very good at this so can potentially lead to a positive feedback runaway scenario. That works as follows: higher temperatures cause ever more water to evaporate and then drive temperatures even higher and on and on it goes - while there is an available liquid water reservoir.

Through water vapour's effectiveness at blocking IR, the outward longwave radiation flux eventually flatlines. If the incoming Solar flux is constantly greater than that outgoing flatline value, the planet is tipped out of radiative equilibrium and we have that runaway. If you like, it has a fever. The reservoir for water vapour - the oceans - is vast. That means the system may only be able to return to radiative equilibrium once the runaway process has stopped. In the extreme runaway greenhouse effect, that cessation may only happen at the point when the whole ocean has evaporated.

On present-day Earth, there is a strong temperature inversion, called the tropopause. It is situated between the troposphere and stratosphere. You can see it on thundery days when the tops of storm-clouds spread out beneath it to form the familiar anvil-shapes. The tropopause thus forms an effective barrier to moisture getting into the stratosphere. At the height of the tropopause on Earth, in any case, it's already too cold for water to remain in the vapour phase. The wispy clouds making up thunderstorm anvils consist of ice crystals. This impediment to water vapour's ascent is often referred to as a 'cold trap'.

In a runaway scenario, such as that proposed for Venus, no such impediment exists. This means the upper atmosphere would have become moist too. On Venus, the troposphere extends to a much greater height than on Earth. There is no stratosphere - we're talking about a very different situation here. That is critical because water vapour, upon reaching such great heights, has energetic Solar ultraviolet (UV) radiation to contend with. The UV is effective at splitting the H2O molecule into its constituent elements. Once that has happened, the hydrogen in particular is easily lost to space. One can envisage that once a runaway greenhouse effect got going, Venus' water content got steadily depleted in this manner through time. If Venus ever had oceans, they must have evaporated into oblivion. Because of the 'cold trap', this form of water-depletion is of very little significance on Earth - thankfully.

Once that water was lost, the chemical processes that lock up carbon in rocks on Earth could not operate. All of them involve water somewhere. Thereafter, every addition of carbon to the atmosphere, large or small, stayed up there. Most CO2 was probably of volcanic origin. The result was the 96.5% CO2 atmosphere and hellish surface temperature of Venus today.

Earth and the Runaway: Past and Future

Currently, Earth is well under the absorbed solar radiation threshold for a runaway greenhouse effect to occur. Its water condenses and is recycled back to the surface as rain, rather than accumulating indefinitely throughout the atmosphere. The opposite is true for CO2, which builds up and up through our emissions, only checked by natural removal processes. Note here that the runaway greenhouse threshold is largely independent of CO2 since the IR opacity is swamped by the water vapour effect. This makes it difficult to justify concerns over a CO2-induced runaway on Earth.

However, this immunity to a runaway greenhouse effect will not last forever. The most realistic scenario for Earth entering a runaway occurs a few billion years in the future, when the sun's brightness has substantially increased. Earth will then receive more sunlight than the outgoing longwave radiation escaping to space. A true runaway greenhouse effect is then able to kick in. Caveats apply, though. For example, greater cloud cover could increase planetary albedo and delay this process.

Interestingly, some (e.g. Zahnle et al. 2007) have argued that Earth may have been in a transient runaway greenhouse phase within the first few million years of its existence. Geothermal heat and the heat flow from the moon-forming impact would have made up for the difference between the net solar insolation and the runaway greenhouse threshold. But if this happened it could only have lasted for a relatively short period of time - since we still have plenty of water on Earth.

For further reading, a recent review paper (Gillmann et al. 2022) explores the various hypotheses concerning the evolution of the Venusian atmosphere over geological time. There's also an excellent book chapter (Arney & Kane. 2020, currently available as a PDF at arXiv). As might be expected, difficulties in fieldwork are plural on Venus and designing a probe that survives touchdown and can go on to do the required data-collecting is still some time away. The key piece of evidence we need to confirm the existence of a runaway greenhouse effect in deep time would be for free water having once been present. But it is apparent that large parts of the surface were covered with lava flows from monster volcanoes at some point. Is that evidence nowhere to be seen, or is it just hiding? Time will tell.

Last updated on 21 January 2024 by John Mason. View Archives

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Comments 126 to 150 out of 268:

  1. It always amazes me how many people get the Ideal Gas Law wrong with the 'Pressure causes Temperature' idea. But explaining it never helps, they just don't get it.

  2. Lots of posturing, yet no explanation why the poles of Venus are as hot as the equator, why the night side is as hot as the day side, and why Jupiter, which has an atmosphere made of H2 and He which are not greenhouse gases, has a temperature of 260 F at a depth in the atmosphere where the P is 11 bars.


    [RH] Need I remind you that you are currently skating on thin ice with regards to your commenting privileges. Posting links to blog posts instead of published research and then calling published research "posturing" does not help you. Stick to the published research, if there is any, to support your position, please.

  3. How many times would we have to double Earth's CO2 to be the same as Venus, which is 96% CO2 and is 93 times denser than Earth's? The answer is 18. Starting at 400 and doubling:


    With a climate sensitivity of 2C per doubling, Earth would only be 2 x 18  or 32 C warmer than it is now, using the greenhouse effect of CO2


    [RH] Try using central estimates for CS of 3°C.

  4. Mike Hillis, Skeptical Science is not intended to be an encyclopedia. You need to exert A little independent effort before posting your off topic diatribes.

  5. Also Mike.

    The forcing effect of CO2, at so much per doubling, isn't the same ratio all the way up to those very high concentrations. Additional wavelengths come into play at those higher concentrations, a process called Continuum Absorption comes into play, and the Lapse Rate of the atmosphere of Venus is more like 10.4 Deg C per km vs 6.5 here on Earth. Also there is SO2 present on venus that isn't present here on Earth. And since there is cloud covering the entire planet, not just part of it even though SO2 clouds aren'e as effective as emitters as water clouds, this still produces a bigger GH effect from clouds than here on Earth. Since the Bond Albedo of Venus is around 0.9 - 90% reflection, much from those clouds, the GH effect impact of those clouds would also be substantial.

    You can't extrapolate simply from the current climate on Earth, you actually need to run the radiation modelling programs with venus's atmosphere to get the correct result.

    From the post above "In the dense Venusian CO2 atmosphere, pressure broadening from collisions and the presence of a large number of absorption features unimportant on modern Earth can come into play (figure 1b), which means quick and dirty attempts by Goddard to extrapolate the logarithmic dependence between CO2 and radiative forcing make little sense."

    A better way of thinking about it, is to use the radiation calculations to determine what the effective radiating height for the atmosphere is, the average altitude that radiation to space originates from. For the Earth that is around 5 km up, for Venus it is over 50 km up. The average temperature at that altitude will be at around the effective radiating temperature the planet needs to be at to be in energy balance. For the earth that is -18C. For Venus it is more like -80 - -90 C. So a lapse rate of 6.5, over a 5km altitude makes the surface of the Earth around 32.5C warmer than the effective emission level so around 14-15C.

    For Venus, a lapse rate of 10.2 approximately and an effective emission height of over 50 km gives a surface temperature something of the order of 510-550 C warmer that the effective emission level, so the surface temperature should be something like 420-470C.

  6. Returning to Mike Hillis @ 121:


    "The greenhouse effect doesn't explain why the dark and sunlit sides of Venus are the same temperature, and why the poles are as hot as the equator."

    Actually, it has been predicted since Svante Arrhenius in 1896 that increasing the greenhouse effect will warm the poles more than the equator, in winter more than in summer, and it has also been shown that the greenhouse effect warms nights more than days.  Carried to extremes, these features easilly explain why Venutian nights should be as warm as days, and polar regions as warm as tropical regions in the lower troposphere.  In contrast, no presentation of the theory you appeal to purports to show the same thing.


    "This does"

    The blog post for which you provide a link appeals to a paper showing temperature hotspots at high altitudes to prove that the adiabatic lapse rate applies throughout the entire atmosphere.  That is, it appeals to a paper that falsifies its claim as proof of that claim.  It further claims the existence of the adiabatic lapse rate (where it exists) is proof of their preferred theory (of which more in a later post) even though it is a well known feature, and an important feature of the standard greenhouse theory since Manabe and Wetherald (1967), and a well known feature of all atmospheres in regions dominated by convection long before that.


    "Venus is not like earth, in that its atmosphere directly absorbs sunlight on the way in, via the H2SO4 clouds."

    In fact measured solar flux on the Venutian surface is between 35 and 40 W/m^2 at the surface (see figure 6).  On the other hand, global mean net solar flux (accounting for differences in latitude, season and the day night cycle) in only about 8 W/m^2.  Both of these are substantially smaller than is the case on Earth, due to the thick cloud, but they are more than sufficient to generate an adiabatic lapse rate in the Venutian troposphere (as is proven by its existence).  If all solar heating was dissipated in the clouds, as you claim, the surface would be cooler than the clouds, just as the tropopause is cooler than the stratosphere due to the heating of ozone in the stratosphere by UV radiation on Earth.  That is, if you were right about this point, the very precondition for validity of your preferred (in not understood) theory would be false.


    "The reason the temperature everywhere on Venus is the same is, gravity is the same all around Venus."

    The only way gravity 'generates' energy, and hence raises temperatures, is the conversion of gravitational potential energy to kinetic energy by masses falling towards the surface.  For an atmosphere in equilibrium, there is no net infall of material, and hence no net energy conversion from potential to kinetic forms.  The atmospheres of rocky planets, including Earth and Venus are very thin, and have reached quasi-equilibrium a long time ago.  Ergo, no net conversion of potential energy to kinetic energy, and no overall warming of the atmosphere by gravitation.  End of story.  Your explanation is a non-starter, and shows all the accumen demonstrated by various inventors of perpetual motion machines (which it would allow, if valid).

  7. Tom Curtis 131

    The atmospheres of rocky planets, including Earth and Venus are very thin, and have reached quasi-equilibrium a long time ago. Ergo, no net conversion of potential energy to kinetic energy, and no overall warming of the atmosphere by gravitation. End of story. Your explanation is a non-starter, and shows all the accumen demonstrated by various inventors of perpetual motion machines (which it would allow, if valid).

    Quasi equilibrium is not equilibrium. Small motion, even brownian motion, is enough. All small parcels of gas, even single molecules, generate heat on the way in and release it on the way out. Gas moves in, compresses, heats up, releases heat to the neighboring gas at lower elevation, moves back up, cools, absorbs heat from neaghboring gas at higher elevation, moves back down, etc. If you don't understand how vertical movement of gas generates heat and transfers it in a downward direction, then you probably don't understand why Death Valley is so hot, or why the San Gabriel and Santa Ana winds heat up as the elevation decrease, even at night. These are called katabatic winds and happen all over Antarctica. In the extreme, as on Venus and Jupiter, they explain everything. Taken to the extreme extreme, near the core of Jupiter, the temperature is 20,000 K. and the Kelvin Helmholtz theory isn't even necessary (that theory requires permanent compression....not needed).

    Please no talk about perpetual motion machines. The solar system has been in motion for only 4.6 by, and that's a long time but not perpetual. Tidal forces and the friction it gererates will eventually stop the rotation of Venus, but until then, the motion, all motion, within its atmosphere, will continue to generate heat katabatically.

  8. Mike Hillis @132, don't be a fool.  Downward motion of air heats the air, but upward motion of air cools it.  If the same amount moves up as down, there is no net heat generated, and hence no possibility that this mechanism will raise temperatures above what they would have been from solar input alone.  As it happens, convective equilibrium is achieved within hours in the troposphere.  Given that, the idea that after 4.6 billion years there continues to be a net settling of the atmosphere that is needed to generate excess heat is absurd.

  9. Mike Hillis:
    Did you check out KR’s link in @123? Look at figure 3c on page 4 (lower left). The red curve shows measurements by the Soviet Venera 15 probe of outgoing IR radiation from Venus.

    Do you have any idea of what that curve would look like if the extreme temperature on Venus was caused by gravitational compression – or any other heat source – rather than IR absorption in the atmosphere?

    Hint: You would have to expand the y-axis a lot!

  10. Tom @ 133 as I already said, as the air moves down it adds heat to the air it decends to. As it ascends, it takes heat from the air it ascends to. In BOTH directions, it transfers heat from higher to lower. Read again what I said.

  11. HK @ 134 Venus is much hotter than Earth and radiates at shorter wavelengths, so we can pay more attention to the 2 and 3 4.5 micron bands and less to the 15 mike band. Take another look at the graph.

  12. 2 and 3 and 4.5 I meant

  13. And just to be clear on Tom Curtis @ 133:

    "Given that, the idea that after 4.6 billion years there continues to be a net settling of the atmosphere that is needed to generate excess heat is absurd."

    We are not talking about generating heat. We are talking about transferring heat, in this case, transferring it from every layer of the atmosphere to the surface. The heat comes from the sun, absorbed by the atmosphere so that only 10% of the light that falls on Venus ever reaches the surface. The bulk of the heat is transferred to the surface by the gravity heat pump mechanism I described.

  14. Mike Hillis @135, you also said:

    "Tidal forces and the friction it gererates will eventually stop the rotation of Venus, but until then, the motion, all motion, within its atmosphere, will continue to generate heat katabatically."

    What you should have said is that, "until then, the motion, all motion, within its atmosphere, will continue to generate and remove heat in equal proportions katabatically" unless you take the delussory view that all atmospheric motion on Venus is downward.

    What this mechanism does, and the only thing it does, is to generate the lapse rate in the troposphere.  That is, it establishes a linear relationship between the temperature difference and distance along the vertical axis within the troposphere.  It cannot, by itself, determine the exact value of the temperature at any point in the troposphere.

  15. Mike Hillis, just to be clear here - do you believe that if you put venus atmosphere into an ordinary GCM using only known physics, then the temperature and isothermal structure of surface is not reproduced?

    ie it is "unexplained" by known physics?

  16. Mike Hillis @136:
    My point is that Venera’s measurements clearly show that the IR radiation escaping from Venus can’t come from near its surface, but from much colder and therefore much less radiating layers in its upper atmosphere.
    If the high temperature was caused by any physical process that adds heat rather than slows down the heat loss to space (as the GHE does), the spectrum of the outgoing IR from Venus would look completely different. Using the wavenumber scale (as done in the graph), the peak radiation would be more than 20 times higher (thus the need to enlarge the y-axis!), and shifted to about 1440 cm-1.

    BTW, the 15 µm band (667 cm-1) is important for the Venusian greenhouse effect exactly because almost all the heat loss to space happens from the very cold, upper layers of the atmosphere and not from near the surface.

  17. Mike Hillis at @135

    "as I already said, as the air moves down it adds heat to the air it decends to. As it ascends, it takes heat from the air it ascends to. In BOTH directions, it transfers heat from higher to lower"

    Actually Mike, you have this back-to-front. As air moves down heat is added to it from the surrouning air. And as air rises heat is removed from it by the surrounding air. You are leaving important aspects of the problem out - potential energy changes and work.

    A parcel of air that is rising in the atmosphere is being lifted by some force, air pressure, buoyancy, whatever. So work is being done on it. However, because it is rising, the air parcel is also gaining potential energy. When we work out the math, the work done on the parcel exactly matchs the potential energy gain. So conservation of energy says no net change in the energy of the parcel. At the scale of air movements in the atmosphere there is little mixing between parcels, so no scope for significant heat transfer between them And in a dense atmosphere radiative transfer is very poor. So the movement of the air parcel is essentially adiabatic - no net heat flow in or out.

    So the parcel would rise to a higher altitude essentially unchanged same volume, same pressure, same temperature. However, pressure can't stay the same. At higher altitude air pressure is lower, and air pressure must equalise. So the parcel has to expand to equalise pressure with the surrounding air. But in order to expand the parcel has to push the other parcels around it aside to make room for its expansion. It has to do work on them. So there is an energy transfer from the rising parcel to the surrounding air as work. But conservation of energy says this energy has to come from somewhere. And the only energy source available is the internal energy of the rising air parcel. In order to supply the energy needed to push other air parcels aside, the rising parcel loses internal energy. Its temperature drops as it transfers energy to its surroundings.

    For descending air parcel it is the reverse. as it descends, pressure equalisation means that the surrounding air compresses the parcel, doing work on it, adding to its total energy which since the situation is adiabatic can only manifest as an increase in the temperature of the parcel.

    Rising air heats its surroundings and is thus cooled by them, falling air is heated by its surroundings and cools them.

  18. Adiabatic changes in temperature don't add or lose total heat, because when the volume goes down the T goes up so total heat in parcel remains the same. Just the temperature changes. The amount of heat in the parcel of air remains the same, all that changes in the temperature and volume according to

    PV = nRT

    So if PV goes up, T goes up, but when the temperature goes up the total heat contained stays the same because the volume goes down. That's how it works. Heat stays the same and volume goes down, the temperature goes up. Follow with me closely:

    1. Parcel moves down and compresses

    2. Heat stays the same but T goes up

    3. Parcel equilibiates T with lower elevation surrounding air by adding heat to it

    4. Parcel moves up and expands

    5. Heat in parcel stays the same but T goes down

    6. Surrounding air adds heat to parcel to equilibriate T

    All heat added to parcel from surrounding air is at higher elevation, all heat lost from parcel is at lower, so heat is moved from high elevation towards low until it reaches the surface.

    This is for ALL vertical motion of air, whether is be large air masses, small parcels, or brownian motion, and at any and all elevations.

    And since horizontal motion of air is many times faster than vertical, the air parcels are quickly moving around the planet, which is why the poles on Venus are the same temperature as the equator, and the night side is at warm as the daylit side.

    Glenn @ 142 says

    this energy has to come from somewhere. And the only energy source available is the internal energy of the rising air parcel

    No, the source of energy is the Sun


    [RH] Please avoid using all caps, per comments policy. 

  19. Mike Hills,

    Your arguments started out interesting but have gone way down.  I suggest you review basic chemistry and physics before you post again.  You need to stop reading from the blog source you are getting your information from.  Keep in mind that Steve Goddard thinks CO2 can fall as snow at the south pole and be sequestered there forever.  If you want to convince readers here you have to get the High School Chemistry (which I teach) correct.

    Heat and temperature are directly proportional in a given parcel of air.  If the temperature increases as the parcel as it sinks, the heat increases. The heat has to come from somewhere.  It cannot come from the parcel itself as that would violate the first law of thermodynamics.  Glenn's explaination that the energy comes from the work the surroundings does (or that a rising parcel does on the surroundings) is the correct one.    Read his post again if you are unclear about where the heat comes from.

    Venus is the classic example of a runaway greenhouse effect.  Arguing that Venus is not a greenhouse planet will not get you any converts at a scientific site.  

    Can you find a scientific reference (paper or textbook) that caims Venus is not a greenhouse (I note that you have not referred to any scientific papers in your arguments, only blog science)?  If you cannot perhaps you should consider that it is because Venus really is a greenhouse and your blog science is incorrect.

    Your claim that heat can be transferred from the cold upper atmosphere to the warmer lower atmosphere is also a violation of the laws of thermodynamics.

    I will try not to comment again since dogpiling is against the comments policy.

  20. Mike Hillis @143:
    "Adiabatic changes in temperature don't add or lose total heat...."

    Are you saying that adiabatic processes can’t change the total heat content in the atmosphere of Venus (or any other planet) and that the high temperature near the surface is only caused by a redistribution of heat?

    (A short yes or no is sufficient)

  21. @144

    Heat and temperature are directly proportional in a given parcel of air.

    Yes, as long as you don't change the pressure or volume, which can change the T without changing heat content. High school chemistry teachers should know this.

    pV = nRT says if you increase PV, the T goes up even though you have not added heat. The work done to change the parcel's elevation and raise or lower the PV is uneven solar heating of the atmosphere.

    I will not state my argument again because repeating oneself is against comments policy.

  22. @ 145

    Are you saying that adiabatic processes can’t change the total heat content in the atmosphere of Venus (or any other planet) and that the high temperature near the surface is only caused by a redistribution of heat?

    Yup. Only the sun can change the total heat content of the atmosphere.

  23. Michael sweet @144

    Keep in mind that Steve Goddard thinks CO2 can fall as snow at the south pole and be sequestered there forever.

    That is an error. This is what Steve Goddard actually says:

  24. Mike Hills,

    Any  chemistry text will say that Boyles law is PV=Constant (Wikipedia) or page 297 Corwin Introductory Chemistry (textbook for the local Community College). Your claim that PV can somehow increase on their own without the addition of energy from an outside source is simply false. You must provide a scientific reference (blog science is not good enough) to support your absurd claim that PV can increase on their own.  Since PV = constant, the only way to change the temperature is to add energy.  Read Glen's comment for the correct explaination of how the work done by the atmosphere changes the heat content of the parcel.  (Heat and work are both forms of energy so work done = heat increase).

    The thread at WUWT where Goddard claimed that CO2 would fall as snow at the south pole was deleted after even Watts realized that it made him look stupid to have such junk on his site.  Goddard was then banned from WUWT for being so unscientific.  (Imagine what it takes to get banned from WUWT for being unscientific!!)

    It is clear that this thread is a waste of time and others have been doing a good job countering your blog "science".  I will no longer comment.

  25. @ 149

    From your link to Wikipedia:

    "P V = k where P is the pressure of the gas, V is the volume of the gas, and k is a constant.

    The equation states that product of pressure and volume is a constant for a given mass of confined gas as long as the temperature is constant.

    So, as long as T is constant and the gas is confined (V is constant), then, yeah.

    For the rest of us, PV = nRT



    [RH] Corrected comment @151.

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