By Steve Goddard
ESA’s Venus Express mission has been studying the planet and a basic atmospheric model is emerging.
Venus has long been the CO2 bogeyman of climate science. In my last piece about Venus I laid out arguments against the claim that it is a runaway greenhouse which makes Venus hot. This generated a lot of discussion. I’m not going to review that discussion, but instead will pose a few ideas which should make the concepts clear to almost everybody.
If there were no Sun (or other external energy source) atmospheric temperature would approach absolute zero. As a result there would be almost no atmospheric pressure on any planet -> PV = nRT.
Because we have a sun providing energy to the periphery of the atmospheric system, the atmosphere circulates vertically and horizontally to maintain equilibrium. Falling air moves to regions of higher pressure, compresses and warms. The greater the pressure, the greater the warming. Rising air moves to regions of lower pressure, expands, and cools. The amount of warming (or cooling) per unit distance is described as the “lapse rate.” On Earth the dry lapse rate is 9.760 K/km. On Venus, the dry lapse rate is similar at 10.468 K/km. This means that with each km of elevation you gain on either Earth or Venus, the temperature drops by about 10C.
It is very important to note that despite radically different compositions, both atmospheres have approximately the same dry lapse rate. This tells us that the primary factor affecting the temperature is the thickness of the atmosphere, not the composition. Because Venus has a much thicker atmosphere than Earth, the temperature is much higher.
dT = -10 * dh where T is temperature and h is height.
With a constant lapse rate, an atmosphere twice as thick would be twice as warm. Three times as thick would be three times as warm. etc. Now let’s do some experiments using this information.
Experiment # 1 – Atmospheric pressure on Venus’ surface is 92 times larger than earth, because the atmosphere is much thicker and thus weighs more. Now suppose that we could instantly change the molecular composition of Venus atmosphere to match that of Earth. Because the lapse rate of Earth’s atmosphere is very similar to that of Venus, we would see little change in Venus temperature.
Experiment #2 – Now, lets keep the atmospheric composition of Venus constant, but instead remove almost 91/92 of it – to make the mass and thickness of Venus atmosphere similar to earth. Because lapse rates are similar between the two planets, temperatures would become similar to those on earth.
Experiment #3 – Let’s take Earth’s atmosphere and replace the composition with that of Venus. Because the lapse rates are similar, the temperature on Earth would not change very much.
Experiment #4 – Let’s keep the composition of Earth’s atmosphere fixed, but increase the amount of gas in the atmosphere by 92X. Because the lapse rates are similar, the temperature on Earth would become very hot, like Venus.
Now let’s look at measured data :
http://www.astro.wisc.edu/~townsend/resource/teaching/diploma/venus-t.gif
http://www.astro.wisc.edu/~townsend/resource/teaching/diploma/venus-p.gif
Note that at one Earth atmospheric pressure on Venus (altitude 50km) temperatures are only about 50 degrees warmer than earth temperatures. This is another indication that atmospheric composition is less important than thickness.
Conclusions : It isn’t the large amount of CO2 which makes Venus hot, rather it is the thick atmosphere being continuously heated by external sources. It isn’t the lack of CO2 on Earth which keeps Earth relatively cool, rather it is the thin atmosphere. Mars is even colder than earth despite having a 95% CO2 atmosphere, because it’s atmosphere is very thin. If greenhouse gases were responsible for the high temperatures on Venus (rather than atmospheric thickness) we would mathematically have to see a much higher lapse rate than on Earth – but we don’t.
WUWT commentor Julian Braggins provided a very useful link which adds a lot of important information.
“The much ballyhooed greenhouse effect of Venus’s carbon dioxide atmosphere can account for only part of the heating and evidence for other heating mechanisms is now in a turmoil,” confirmed Richard Kerr in Science magazine in 1980.
The greenhouse theory does not explain the even surface temperatures from the equator to the poles: “atmospheric temperature and pressure in most of the atmosphere (99 percent of it) are almost identical everywhere on Venus – at the equator, at high latitudes, and in both the planet’s day and night hemispheres. This, in turn, means the Venus weather machine is very efficient in distributing heat evenly,” suggested NASA News in April 1979. Firsoff pointed out the fallacy of the last statement: “To say that the vigorous circulation (of the atmosphere) smooths out the temperature differences will not do, for, firstly, if these differences were smoothed out the flow would stop and, secondly, an effect cannot be its own cause. We are thus left with an unresolved contradiction.”
======================================================
An update for those interested in what Venus looks like at the surface.
On March 1, 1982, the Soviet Venera 13 lander survived for 127 minutes (the planned design life was 32 minutes) in an environment with a temperature of 457 °C (855 °F) and a pressure of 89 Earth atmospheres (9.0 MPa). The photo composite above shows the soil and rocks near the lander.
Here’s another Venera image that shows a hint of yellow atmosphere. – Anthony
RE: stevengoddard: (May 10, 2010 at 8:50 am) “P = cT/V where c is a constant”
I believe the fallacy here with the use of the ideal gas law may be that it only applies in those cases where no net transfer of energy occurs. Once energy transfer is allowed then all bets are off.
“Isothermal and Adiabatic Processes. A process that takes place at a constant temperature is called isothermal Process. For a gas expanding isothermally the general law becomes
PV=mRT=constant
which states that the pressure decreases as the volume increases (Boyle’s law). When the expansion or compression of a gas takes place without transfer of heat to or from the gas, the process is called adiabatic. An ideally adiabatic process would have to take place in a container whose walls were perfect thermal insulators. The practical cases in which the expansion or compression of the gas takes place so rapidly that there is negligible heat transfer may be treated as adiabatic processes.”
College Physics Weber, White, and Manning, pp289, 1952
Steven,
Great post, and thanks for answering comments. That really fleshed out the idea for me.
It appear fair to say changing the Earth’s temp to something like Venus’ would be overwhelmingly dependent on pressure and only slightly on composition. I also like very much the idea Venus never had a less dense atmosphere.
Smokey: May 10, 2010 at 9:52 am
Your sense of smell is quite impressive! Not so good re the “coasting”. I am also under no “heat” here. I am not the one misinterpreting the principles of Physics. Steve is. In posting his proposal, he was, in effect, asking for “heat” to be directed at him. If none had been warranted, I would not have provided any, but “heat” was not my intention – simply clarification. I would suggest that Steve is the one having a hard time with the “heat”.
stevengoddard: May 10, 2010 at 9:59 am
My “complaints” were very specific for the first posts that I made. I am also not appealing to “my own authority”. Everything I said is part of standard Thermodynamics, and can be readily verified by you or anyone else. You’re missing the your own point here in suggesting that I provide a “counter-proposal”. I was not the one who proposed the explanation for Venus. You did. I do not know enough about Venus to try and explain what might be going on there. I doubt that anyone else does either in any quantitative way at the present time. I do, however, fully understand Thermodynamics, which was the subject matter of my comments.
/dr.bill
Spector
They are different forms of the same equation. I was just assuming that nR is a constant c, because the number of molecules isn’t changing in the atmosphere.
There are a lot of very complex dynamics going on in the real atmosphere, which is why we have climate models.
Spector
There is no “fallacy.” Rather it is simplifications and approximations to demonstrate the underlying principles.
dr.bill
There are dozens of degrees of freedom in the system governing the atmosphere. No simple equation is going to accurately explain everything that is going on from absolute zero up to the melting point of basalt, and you can nitpick from now to eternity.
Unless you have a fundamental disagreement that the high temperature of Venus is primarily caused by the high atmospheric pressure, what is your point?
TallDave
Exactly, thanks.
I wouldn’t say that Venus never had a thin atmosphere – we don’t have any way of knowing that. It probably built up over some period of time.
But we can say that Earth will never become like Venus, short of a cataclysmic event which raises Earth’s temperature well over 850C.
stevengoddard: May 10, 2010 at 11:19 am
“…you can nitpick from now to eternity.”
Nitpicking is at the heart of science. The details matter.
Regarding “what is my point?”, I would just say the following:
The high atmospheric pressure of Venus is caused by the fact that it has a lot of atmosphere. I don’t know how it got all that atmosphere, and neither does anyone else. Once that atmosphere is present, however, it is not a foregone conclusion that it will get hot. In order for any atmosphere to have a lapse rate, and vertically declining temperature profile, two things are needed: a source of energy at the bottom, and a gravitational field to provide the buoyancy effect that allows the gases to rise. The principal energy source on Earth is the Solar energy absorbed by the surface, which then warms the air, which then rises, cools, sinks, gets re-heated, and all the rest, over and over again. I don’t know what is providing the heating on Venus, and neither does anyone else, but it is not caused by simple pressure. If simple pressure were the cause of temperature, you wouldn’t be able to touch a SCUBA tank.
Off-topic: I was rather disappointed to have you and Smokey, both of whom I respect, “throw darts” at me because I happen to have an education. I worked for that education, and I financed it by working in construction and mining, and by winning scholarships. Ever since collecting all my “pieces of paper”, I have worked hard to improve my understanding of Science and the world in general. I continue to do so, and I have learned a great deal from things I have read on WUWT. To be denigrated simply because I have a PhD in Physics makes about as much sense as denigrating someone because they don’t.
/dr.bill
I’m confused, Steve.
Why do the gases in Venus not radiate like Earth’s atmosphere appears to? After all, if heat flux is proportional to T^4, then we should get some very significant radiative loss from the lower atmosphere. Apparently mean Venusian emissivity is over 0.8.
So the outgoing heat flow from Venus’ surface is about 8 kW m^-2, and the heat in from the Sun is significantly less than that (Top of atmosphere is what, ~2.6 kW m^-2, most of which is reflected?)
As I see it, the only way to solve this is one of the following:
1) Venus’ isn’t radiating on that scale & it disproves our radiation laws
2) Something is preventing the heat from escaping at that rate
3) Venus is cooling rapidly
4) Conservation of energy is wrong
5) There is a massive source of heat that Venus gets, we don’t, and it’s not the Sun.
Where has my logic gone wrong?
@omnologos says:
May 8, 2010 at 4:11 pm
In particular, the lapse rate is roughly g/Cp, where g is the acceleration due to gravity and Cp is the atmosphere’s specific heat at constant pressure (cp) divided by the molecular weight. It would be interesting to find out why exactly Cp for Venus would only be 85% of Earth’s.
Well, you’re using little-g, which is not independent of the planet’s mass. Big G would be the universal gravitational constant here. So assuming you mean to use little g, then both Cp and ‘g’ would change between Earth and Venus.
dr. bill,
My apologies for the perfumed academic comment. You write well. Why don’t you write an article for WUWT?
I tend to sympathize more with the people who write the articles, because they’re opening themselves up to some serious criticism here. It’s not like the climate peer review referees who hand-wave their friends’ papers through to friendly journals, while everyone puts roadblocks in front of skeptics’ submissions.
This is how science should be. When you post an article here, you don’t have pals to run interference like climate related journals do.
dr.bill
Earth would also have a lot of atmosphere, except that we have huge amounts of CO2 sequestered in limestones which formed in the oceans.
I r have an iducation two from some real guud universitees.
MarkR
I think the Real Climate explanation is a good start. The atmosphere of Venus has a very large thermal mass and doesn’t change temperature quickly.
dr.bill
I looked some more at your post and it gave the distinct impression that you did not read my article or comments carefully. Your claim that I am blaming static pressure for the heat is absurd.
I’ve estimated the surface temperature of the Earth if the oceans were to vaporize. Let’s call it the
“STEAM-BATH EARTH”
scenario.
(“Steam-bath Earth”, you heard it here first, May 10, 2010.)
(Let me also claim here a first for “Pressure-cooker Earth scenario” while I’m at it. and “Sauna Earth scenario”, “Steam Room Earth”, “Jacuzzi Earth”, “Super-sauna Earth”, “Sweat lodge Earth”, “Fat Farm Earth”, also replace “Earth” in any of the preceding with “world” or “planet”. “Pressure-cooker Planet”. That has a sort of ring, don’t it.)
At a surface pressure of 247 atmospheres with an atmospheric depth of 139 km from the surface to the altitude of 1 atm pressure, the surface temperature could potentially exceed 850 deg C, depending on the environmental lapse rate. (I used 4 C/km, a little below the adiabatic lapse rate for water vapor, which is roughly half that of air or CO2.) That temperature would exceed the decomposition temperature of limestone, releasing CO2 from rock to the atmosphere, eventually turning the Earth into Venus. At this pressure the water vapor would be supercritical, whatever that’s worth.
Of course, this is strictly a small Excel “back of envelope”, and who really knows what kind of chemical reaction would occur under those extreme conditions! Also, it would depend on how the 100% cloud cover affects Earth’s albedo. As I mentioned many posts ago, some clouds have very high albedo while others have a very low albedo, so it all depends on what type of clouds dominate. Another caveat: the lapse rate could be lower. We all know how dark it gets in a thunderstorm. Water vapor clouds could reduce the sunlight reaching the surface to lower levels than on Venus, thereby reducing the surface temperature and the environmental lapse rate.
HOWEVER, I have the transmittance spectrum plots of water vapor right in front of me for present-day Earth conditions in the tropics and these plots tell me that with a few thousand times as much water vapor as that, the “Fat farm Earth” scenario would be exceedingly good at obstructing nearly 100% of infrared longer than 1 micron at that kind of optical depth. Therefore it could take VERY LITTLE sunlight reaching the surface to raise temperatures to 850C in a “Super-sauna world”.
The point being,
Steve Goddard, “So certain are you? Always with you it cannot be done. Hear you nothing that I say?”
Steven,
As a quick thought experiment I tried this, but probably got it wrong because it just occured to me.
Venus irradiance at the top of atmosphere is 2613 W/m^2, but about 75% is directly reflected, so the atmosphere absorbs 653 W/m^2. Averaged over the surface area of a ball that’s 163 W/m^2. Only about 65 W/m^2 reaches the surface (again averaged over the surface of the entire planet, day & night).
Since Venus is in thermal equilibrium, it must re-emit 163 W/m^2, which comes from the top of the clouds and up. Stefan Boltzmann’s law puts the temperature at 231 Kelvin, which would be the temperature at the cloud tops. The surface temperature is then found by taking the adiabatic lapse rate, the height of the cloud tops, and the temperature of the cloud tops, just as Carl Sagan did.
So now, to eliminate the greenhouse effect, I eliminate the radiation that hits the surface, which is about 65 W/m^2 (this needs to be double checked – it’s based on 10% of the top of atmosphere). Since that radiation never bounces back up to the cloud tops (via whatever route), the atmosphere now only radiates 98 W/m^2 (163 – 65). That gives a Stefan-Boltzmann temperature of 203 K at the cloud tops, a decrease of only 28 degrees.
If the cloud tops stay about where they were, the adiabatic lapse rate would give a decrease in Venus surface temperature of about 28 degrees, and there can be no greenhouse effect operating because it no longer has any surface illumination at all, which is by definition a requirement of the greenhouse effect.
“Initially Earth didn’t have limestone either, supposedly, but I have not heard any account from a single geologist or planetary scientist suggesting that Earth’s atmospheric pressure was every more than a few atmospheres, so…”
During the Hadean period, an Earth atmosphere of 200atm has been suggested. The surface pressure was so high that a liquid ocean is likely, even though the surface temperature was far above 100C.
“In order for any atmosphere to have a lapse rate, and vertically declining temperature profile, two things are needed: a source of energy at the bottom, and a gravitational field to provide the buoyancy effect that allows the gases to rise.”
Strictly speaking, it requires a source of energy to maintain permanent temperature differences at the surface, to drive convection. Only a difference in temperature can drive a heat engine to do work.
“I don’t know what is providing the heating on Venus, and neither does anyone else, but it is not caused by simple pressure.”
Not simple pressure, no.
There are two essential factors to the greenhouse effect.
There needs to be sufficient differential heating at the surface to drive convection. This differential heating does not have to be very much. It can be as small as you like, so long as it drives convection faster than heat can diffuse. So long as you get vertical mixing being forced, an adiabatic lapse rate will dominate.
And the emission of radiation to space needs to be at least partly from high above the surface. (Radiation internal to the atmosphere has no effect.) While the adiabatic lapse rate sets the gradient of the straight line, the emission to space sets the intercept.
The visible surface at the wavelengths at which the planet radiates, which in the case of a planet with an opaque atmosphere is high above the solid surface, settles at the radiative equilibrium temperature. Then gas descending from this altitude is compressed and increases in temperature. It’s important to say it isn’t “heated”, because no heat is exchanged in order to do so, and in particular, this means there is absolutely no need for a major source of heat at the surface to achieve and maintain this high temperature. The direct source of the energy is the gravitational potential energy, but the conversion is driven by the entropy driving the convection.
The physics is essentially very similar to that of a refrigerator. Gas is driven round a cycle during which it is compressed and expanded, and as a result maintains a temperature gradient between the two ends. The temperature of one end of the heat pump is anchored to a large heat reservoir (the outside of the refrigerator, or outer space) and the temperature of the other is held by the heat pump in a fixed relationship to it (the coolbox, or the surface of the planet). Convection acts as the refrigerator’s pump/motor.
The primary difference between Earth and Venus for explaining the differing climate is the mass of the atmosphere, but there are other essential aspects to the physics too.
steven goddard,
I want to express again my appreciation for this post. I’ve been trying to tell people about this way of looking at the physics for some considerable time. Many I talked to understood it immediately, but I got a lot of determined and not always constructive opposition, too. So I’m not surprised at the reaction here.
Incidentally, all of this is perfectly standard climate science – as promulgated by the likes of Sagan, Manabe, Ramanathan, and so on in the technical literature. But when talking to the general public, they switch to this nonsensical primary-school version of longwave radiation being “trapped”. I believe this is actually based on a purely-radiative model of a non-convective atmosphere that they use as a toy example for teaching, to which they then try to add in convection as some sort of minor modification to it. However, with convection, the “greenhouse effect” is by an entirely different mechanism to which the non-convective/radiative language is inappropriate.
But it’s an absolute joy to see it flying from the masthead at WUWT. So my thanks.
Jbar
At earth surface temperatures, water vapour saturates and condenses between 0 and 100mb. You can’t get a vapour pressure on earth greater than 100mb (1/10th of an atmosphere) outside of an enclosed vessel.
Need to qualify that last remark. A volcano or fire could produce vapour pressures on the surface of 1000mb.
Ben’s comments below express my views better than I can. Apparently I can not compose my concern with the basic physics in the last two Venus posts without incurring “moderation”. I acccept this this is my fault alone for being too passionate. However, if basic physics concepts need to be altered to discount the possibility of anthropogenic global warming perhaps that is its greatest validation.
Ben Schumacher says:
May 9, 2010 at 2:06 pm
I keep expecting this thread to be about WHY Venus has developed such a strong greenhouse effect, and whether the term “runaway greenhouse” appropriately describes this process. Fascinating question, and present theories involve a good deal of speculation. I would probably count as a moderate AGW skeptic — a “luke-warmer” in common parlance — but the discussion here does not inspire me with confidence that this community has a firm grasp on the basic physics. Sorry to be so blunt, but the thing is pretty distressing to someone who reads WUWT regularly and with pleasure.
re Smokey: May 10, 2010 at 12:36 pm
(and peripherally, Steve)
Don’t sweat the “perfumed” or “taking heat” comments. I work in an environment where I’m out-numbered at least 10 to 1 by devoted Koolaid drinkers, and I’ve taken a lot of abuse over the past 10 years or so by (quite publicly) pointing out the flaws in their religion. I don’t give a rat’s ass about the abuse, but I do care about the corruption of Science, so I just keep hammering away at them, as they keep jumping from one ill-conceived imminent calamity to the next.
In the case of Steve’s article, I interpreted him to say that pressure caused temperature, and (by my perhaps flawed reading) he still appears to be saying that. Perhaps it’s just a matter of semantics, and perhaps we can just give that a rest. I also am appreciative of the fact that people who present full-blown articles here are opening themselves up to attacks of all kinds, and often from those who have the worst of motives. You may rest assured that I am not among those people. Any comment I make is intended to improve understanding, or to point out what I see as an error. Whether my comments accomplish that, of course, is another matter, but I am also happy to have errors in my own thinking pointed out to me. The final goal is to know what is real, no matter who proposes it.
I look forward to reading more from both of you in the future.
/dr.bill
Maybe OT, maybe not;
Another torpedo in Titanic;
http://www.climatedepot.com/a/6506/Atmospheric-Scientist-Slaps-Down-255-Warming-Scientists-Letter-There-is-no-scientific-evidence-that-burning-of-fossil-fuel-is-responsible-for-climate-change
MarkR
It’s number 2: “something is preventing the heat from escaping at that rate.”
That “something” is the infrared absorbance of CO2.
It HAS to be, because there isn’t 8000 W/m2 shining back down on the planet from space, and there sure as hell isn’t 8000 W/m2 coming from the planet’s interior. Not even close.
On Earth, with only 3 pounds of CO2 in the atmosphere per square foot of surface, CO2’s absorbance spectrum is fairly narrow, much less than that of water vapor.
On Venus, with almost 95 TONS of CO2 in the atmosphere per square foot of surface, or almost 40 pickup trucks/ sq foot (yes, a new unit of measure), CO2’s absorbance spectrum becomes so broad that it blocks out almost all infrared from 2 microns to 28 microns. What little water vapor there is in the upper atmosphere (similar in mass to Earth, actually) blocks everything from 28 microns and higher, just like it does on Earth. (RealClimate stated that it is impossible to image Venus’s surface in infrared except for a narrow IR “window” close to 1 micron wavelength.)
So out of the 8000 watts (or 12,000, depending on who’s calculating, but let’s use your 8000 number) leaving the surface, the thick CO2 atmosphere reflects more than 7900 watts back to the surface. The difference, the amount that makes it out to space, is enough to balance out what little sunlight heats the surface, averaged around the planet, so that Venus’s surface temperature remains constant even with this enormous flux of energy flowing up and down.
The massiveness of Venus’s atmosphere was invoked to explain why the surface temperature is uniform around the globe even on the dark side where there is little or no illumination. It is massive enough that it can transport the small amount of solar heating energy from the day side all the way around to the night side with low wind speed. This is especially true since it is not just surface winds carrying that energy but wind over kilometers of altitude that is constantly radiating 8000 W/m2 up and down between wind and ground while moving a paltry 50 W/m2 equivalent horizontally to the dark side of the planet.
Let us consider what would happen if Venus instead had a thick nitrogen/oxygen atmosphere and somehow had clouds with the same albedo as Venus has today. These gases are transparent to infrared (not counting whatever makes up the clouds). That 8000 W/m2 radiating from the surface would go straight up to the cloud layer unimpeded by the O2 and N2 and vaporize the clouds, and then blast its way out into space, cooling the surface fairly rapidly down to something much cooler. The lapse rate might still cause the surface to be warmer than Earth, but I’m not sure about that. I think we need an actual scientist to do modeling to arrive at an answer. My thinking is that the surface would have to be radiatively in balance with incoming sunlight, which would be pretty low radiation. I suspect there would still be some lapse rate from the surface to the cloud bottoms, but it would have to be much smaller than it is today in order to match the low surface radiation balance in an IR-transparent atmosphere. Of course, the clouds 50km up might reflect infrared back down, but nowhere near as much as a dense CO2 atmosphere.
We know it is the gases on Venus today that reflect the bulk of the radiation back down to the ground and not the clouds, because if Venus’s atmosphere were transparent to infrared, the cloud bottoms should then be almost as hot as the ground, and data says that is not true. As Steve’s graph shows, temperature falls gradually from the surface until it reaches about 60C at the cloud bottoms at 48km altitude. Therefore something is preventing 8000 – 12000 W/m2 of radiation from bouncing off the cloud bottoms and that something is the CO2 greenhouse effect.
dr. Bill,
Pressure doesn’t cause temperature, but a change in pressure does cause a change in temperature, and the temperature change is precisely defined and commonly used in the the enginnering of all heat engines and refrigeration equipment, as related in Nullius in Verba’s comment above.
If parcels of atmosphere are circulated vertically in a gravitational field they must undergo changes in pressure, and those changes in pressure cause changes in temperature. The gas at higher pressures will be hotter than the gas at lower pressures as long as the pressure changes continue (the gas is transported between regions of different pressures).
So if you spin up a jet engine, even without burning any fuel, the combustor inlet temperature (and without fuel the combustor inlet temperature would equal the turbine inlet temperature) would still be hundreds of degrees hotter than the compressor inlet temperature or the turbine exit temperature. The higher pressure in the compressor makes a hot spot that will remain hot for as long as the turbine spins. If you connected the exhaust to the intake in a closed loop you could use it as a refrigerator or a heat pump, with a hot side and a cold side.
The temperature rise in the compressor (due to ideal gas laws) ultimately limits how many compression stages we can use before the added heat from combustion sends the turbine inlet temperature past the limits of the turbine materials, destroying the engine.
As long as the sun keeps the atmosphere of Venus circulating vertically, the temperature difference will exist. As a side note, no military or commercial jet engines compress the air anywhere near the pressures on Venus (92 atmospheres) because they’d melt.
dr.bill
What I am saying is that because of the high pressure on the surface of Venus, adiabatic heating causes the very high temperatures. Those kinds of temperatures aren’t seen on earth because of the lower pressure.