From the University of British Columbia:
Compared to its celestial neighbors Venus and Mars, Earth is a pretty habitable place. So how did we get so lucky? A new study sheds light on the improbable evolutionary path that enabled Earth to sustain life.
The research, published this week in Nature Geoscience, suggests that Earth’s first crust, which was rich in radioactive heat-producing elements such as uranium and potassium, was torn from the planet and lost to space when asteroids bombarded the planet early in its history. This phenomenon, known as impact erosion, helps explain a landmark discovery made over a decade ago about the Earth’s composition.
Researchers with the University of British Columbia and University of California, Santa Barbara say that the early loss of these two elements ultimately determined the evolution of Earth’s plate tectonics, magnetic field and climate.
“The events that define the early formation and bulk composition of Earth govern, in part, the subsequent tectonic, magnetic and climatic histories of our planet, all of which have to work together to create the Earth in which we live,” said Mark Jellinek, a professor in the Department of Earth, Ocean & Atmospheric Sciences at UBC. “It’s these events that potentially differentiate Earth from other planets.”
On Earth, shifting tectonic plates cause regular overturning of Earth’s surface, which steadily cools the underlying mantle, maintains the planet’s strong magnetic field and stimulates volcanic activity. Erupting volcanoes release greenhouse gases from deep inside the planet and regular eruptions help to maintain the habitable climate that distinguishes Earth from all other rocky planets.
Venus is the most similar planet to Earth in terms of size, mass, density, gravity and composition. While Earth has had a stable and habitable climate over geological time, Venus is in a climate catastrophe with a thick carbon dioxide atmosphere and surface temperatures reaching about 470 C. In this study, Jellinek and Matt Jackson, an associate professor at the University of California, explain why the two planets could have evolved so differently.
“Earth could have easily ended up like present day Venus,” said Jellinek. “A key difference that can tip the balance, however, may be differing extents of impact erosion.”
With less impact erosion, Venus would cool episodically with catastrophic swings in the intensity of volcanic activity driving dramatic and billion-year-long swings in climate.
“We played out this impact erosion story forward in time and we were able to show that the effect of the conditions governing the initial composition of a planet can have profound consequences for its evolution. It’s a very special set of circumstances that make Earth.”
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The collision which created the moon wiped out about 3/4 of Earth’s atmosphere. The lower surface pressure resulted in lower temperatures, and allowed liquid water. CO2 dissolved in the oceans and formed carbonates, further lowering the atmospheric pressure. The Earth also gets half the sunlight received by Venus. All of these factors combine to make Earth a lot different from Venus.
I guess you just cannot get attention nowadays without some sort of “OMG things COULD be so WORSE” …
Funny thing with Venus is, everyone is told that it is much hotter than Earth thanks to double solar irradiance and hellish greenhouse effect. Whereas in fact, because of its 0.9 albedo, Venus has (according to NASA’s “venus fact sheet”) a blackbody temperature 70 K LOWER than Earth (184 K Vs 254). It is horribly COLD (not hot !) out there.
I wonder …
Is it not because it is so cold, that atmosphere is so heavy, making surface so hot ?
funny paradox, if true. what you think ?
More scientific rationale for Rare Earth. Rare Earth at least partially explains why most of the “evidence” of Extra Terrestrial Advanced Lifeforms is found on the likes of “Coast to Coast AM.”
This hypothesis is based on the belief that the Earth was subjected to a greater bombardment than was Venus. The objects involved in the bombardment would have been in orbit around the Sun and as Venus is so much closer to the Sun than the Earth is, I can see no scenario where the Earth would have been impacted more heavily.
There is support here for the proposition that the heat at the surface of Venus is attributable to atmospheric mass held within a gravitational field and irradiated by an external source.
Yet I have been involved in many arguments here when regular contributors argued to the effect that it is not atmospheric mass which causes planetary surface temperatures to rise above S-B.
Interesting.
I am getting ready to disappear in a cloud of blue steam. ( No apologies to Hansen)
It also seems strange to me that the “rocky” planets were originally and always “rocky” planets. Since all planets were supposedly made from an accumulation of the matter in the disk around the Sun, WHY would the inner planets NOT also have originated by all of the matter in the position in the disc that they were located? Thus all planets would have been gaseous at first, and then, over billions of years the inner planets would have lost large portions of their gases making up the planets and leaving a “rocky” planet.
maybe the gravitational attraction of the sun ensured that more dust & rocks moved to the inner parts of the disk, then formed rocky planets, while most of the lighter gases stayed in the outer portion & became the gas giants?
The Rocky planets are much better than the Apollo Creed planets. Ask anyone.
Personally I think that the only relevant unlikely event in the Earth’s history is the collision that bound the moon. That collision would have completely altered the composition of the Earth, and IMO probably took a large fraction of the early atmosphere of the Earth off with it.
It is this atmosphere that really differentiates the Earth and Venus. The atmosphere of Venus has a surface pressure of 90 atmospheres. The outermost portion of that atmosphere has to radiate as much energy as it receives, which determines the temperature, more or less, at its cloud tops. As a result of this high density (and its composition, mostly CO_2) the troposphere on Venus extends all the way to 65 km, roughly 10x higher than Earth’s, and it has to be balanced at a proportionally higher greybody temperature at the cloud tops since there is basically no direct radiation loss from the surface. There is no stratosphere on Venus — it goes straight to the mesosphere.
The lapse rate, OTOH, continues all the way to 100 km — 10x that of the Earth — and drops temperatures from over 700 K to under 200 K before turning over, where the Earth has a stratosphere that warms from a minimum temperature well above 200 K before dropping again in the Mesosphere and warming again (irrelevantly) in the thermosphere.
IMO the only reason Venus isn’t conducive to life is that it has way, way too much atmosphere, and tends to lose both O2 and N2 before either one can build up into an atmosphere like Earth’s with CO_2 constantly recycled into bound carbon and oxygen. I agree with the top article that the magnetic properties are important as well — having a strong magnetic field definitely alters the way the solar wind strips off atmosphere at the very top as well as protects the surface from excessive radiation — and suspect that this too is related to the moon-forming collision and its aftermath as much as anything else — but I’d bet “life would find a way” if somebody stripped Venus of 90% of its existing CO_2, allowing it to develop a stratosphere and cooling the surface to where liquid water might accumulate at least at the poles. It might help to take e.g. Europa and drop it onto Venus and wait a billion or so years and see what happened, or to scavenge a dwarf-planet’s worth of large (> 10 km) comets from the Oort cloud and drop them all onto Venus one at a time, blowing away most of its existing atmosphere and releasing a huge cloud of free water to reflect heat away with its high albedo until the surface had time to cool to the greatly reduced ALR to the much lower tropopause.
But we needn’t worry about the Earth becoming “like Venus” unless and until we could increase the total mass in our atmosphere by an order of magnitude or more, and there simply isn’t the raw material or any reasonable process that is going to make that happen.
rgb
rgbatduke said:
“But we needn’t worry about the Earth becoming “like Venus” unless and until we could increase the total mass in our atmosphere by an order of magnitude or more, ”
So is it mass that makes the Earth’s surface 33K warmer than S-B ?
S-B is predicated on unobtanium by design. It is used as a mathematically and existentially ‘pure’ starting point for the rest. And for which if we find anything that violates S-B, then we know that Thermodynamics is as bunk as Phlogistons.
To claim that the Earth is 33K warmer than S-B requires that you give up at least one of:
1) Thermodynamics
2) The propriety of the model for charateristic temperature of a sphere orbiting an (effictively) point souce.
3) The propriety of the model for determining the average temperature of Earth.
Jquip , That 33k number is meaningless red herring useless in any computation . It is not the temperature of a grey , flat spectrum body in our orbit and it obscures the important fact that a gray ball , no matter how light or dark , comes to the same equilibrium temperature , about 278.6 +- ~ 2.3 degrees from peri- to ap- helion , Any difference in temperature is proportional to the 4th roof of the ratio of absorptivity=emissivity wrt the sun’s spectrum , and absorptivity=emissivity wrt the insignificant thermal spectrum of the rest of the celestial sphere . See http://cosy.com/Science/HeartlandBasicBasics.html for the computations including the assumptions creating the irrelevant 33k meme .
Jquip
The Earth’s surface is warmer than the S-B equation predicts but the Earth as a whole when viewed from space is not.
The difference (whether it be 33K or some other figure) is accounted for by surface kinetic energy locked into convective overturning which maintains the hydrostatic balance of the atmosphere as here:
http://www.public.asu.edu/~hhuang38/mae578_lecture_06.pdf
Thus:
“Radiative equilibrium
profile could be unstable;
convection restores it
to stability (or neutrality)”
The convective adjustment occurs without a change in surface temperature unless there is increased TOA insolation or a greater portion of TOA insolation reaching the surface provided atmospheric mass and the strength of the gravitational field remain constant.
Stephen , thanks for the link . I’ve bookmarked it .
So you’ve given up 3). No worries, keep it under your hat as a challenge to others that haven’t thought about the issue.
Why dont we paint a basketball the right color gray and put thermometer on it and launch it into space and make it rotate once every 24 hours? Then we can once and for all measure what temp the earth should be with out an atmosphere.
Bob , see my comment at July 22, 2015 at 9:49 am . This physics is older than relativity and was abstracted from broad experimentation in the 19th century . It is certainly no more difficult than the high school PSSC physics I had half a century ago .
But it would be extremely therapeutic to see it replicated today . It is clear that many posting here , much less any alarmist blog , have never learned even these most basic non-optional equations .
It would be useful to demonstrate them in both the brilliantly simple and affordable manner of the PSSC curriculum and most spectacularly by sticking well spectrally calibrated ball out the window of the space station . ( I don’t understand why engineers in satellite heat budgeting are not more active in these debates . )
When I moved from Manhattan to Colorado , the first thing I did becoming active in this battle for rationality was a “Mr Wizard” style experiment with painted ping-pong balls , http://cosy.com/Science/warm.htm#PingPong , to confirm my , literally childhood , sense of the most essential physics wasn’t just nuts .
It makes it 33 warmer than the greybody temperature, which is not exactly S-B. It isn’t “mass” per se that does it, either — it is atmospheric density, the adiabatic lapse rate, and greenhouse gases all working together that does it. But I’ve explained this maybe four times on two or three different threads in the last couple of days on WUWT and I don’t have the energy to explain it again on yet another thread.
rgb
RGB , we are about 10 degrees warmer than the 278.6 of a gray , flat spectrum ball in our orbit . That is the only number useful in computations .
The 33 degree number is produced by a crude unjustifiable hypothetical step function spectrum assuming a average absorptivity=emissivity of 0.7 over the bulk of the solar spectrum , but an absorptivity=emissivity of 1.0 ( black ) over the longer wavelengths . Here’s a plot showing the computations :
http://cosy.com/Science/AGWpptHypotheticalSpectra.jpg
The 95% of the missing universe is not dark matter, it is charge, the recycling of charge from the sun enters from the poles. It discharges from the equator in the band +30 to -30 degrees north and south. This is the Earths internal heat. It is also the missing part of the puzzle in physics besides the missing part of the universe.
Well I don’t know what a S-B gray body spectrum or Temperature is, I only know what a fictitious BB spectrum or Temperature is, and incidently that BB is required to be isothermal, which it cannot be, unless it has infinite thermal conductivity as well.
So calculating what earth’s Temperature is “supposed” to be is an exercise in futility.
The Temperature of the earth is at all times, exactly what it is supposed to be; no more, and no less.
g
By Kirchhoff ( & Stewart , building on Ritchie’s experiment ) the temperature of a gray , ie : flat spectrum , body , no matter how dark or light , will come to the same temperature as a black body — which simply calculated by summing all the radiant energy impinging on it .
That simple minimal computation explains 97% of our estimated temperature .
There’s a reasonable quantity of CaCO3 which at one time would have contributed a significant amount of CO2 in the Earth’s atmosphere
This article is basically bunk because it deals with plate tectonics as if the plates were floating around on an Earth of constant diameter. It has been conclusively proved that the Earth is expanding in diameter.
Websearch You Tube for videos on “expanding Earth” and you will see that the Earth’s sea bottoms contain very precise measurements of Pangea’s expansion through sea-floor spreading over time, including the directions of the spread.
Whaaaa…?
I suppose they missed the part about subduction on the opposite margins of the plates.
Apropos of not very much at all, this reminds me of a question in my first year maths exam at uni which went very much as follows: “Assuming (if this were possible) that the Earth instantaneously disappeared from the solar system at some point of time, what would then happen to the Moon”? Answer – the Moon would wobble for a while about at first, but soon settle down into (effectively) exactly the same orbit as that of the (former) Earth. So: Earth and Moon are really dual planets, rotating about one another and, together jointly, about the Sun.
But Earth and Moon of course have very different climates and, yes of course, Earth is a pretty habitable place. How did we get so lucky? For myself I’d say essentially pure chance: but with enough stellar systems in the universe thankfully it had to happen somewhere. But I very much doubt we can be the only ones …
To my knowledge no one has contested Émile Clapeyron’s pV = nRT. Because AGW cult seems to upscale laboratory experiments to planetary scale as a standard procedure, how much carbon homo sapiens should theoretically burn to even approach Venus-like temperatures on Earth?
PS. Because carbon is 4th most common chemical element in the our Galaxy and only the 15th on Earth (by mass), we may need Scott to beam Kranken Mare here for the project.
From the University of British Columbia: lucky … evolutionary path … early in its history … early loss … evolution … early formation … create the Earth … events … differentiate Earth … over geological time … evolved so differently … billion-year-long swings … initial composition of a planet … evolution … circumstances that make Earth.”
Is there some reason to actually believe that the early bombardments of Earth and Venus were quantitatively different other than hypothesizing it was so makes their desired result?
I’m getting the faint whiff of models here.
“Venus is in a climate catastrophe”
Seriously?
Catastrophe to who? Who’s suffering?
Venus is what it is.
Is Mars in a climate catastrophe, too?
Follow up:
Was Earth in a climate catastrophe when it was putatively stripped of 3/4 of its atmosphere? You would think so. Or did that solve the putatively existing climate catastrophe?
What’s the opposite of “be careful what you wish for”? “Be grateful what you didn’t wish for”?
Yes, Mars is in a major catastrophe. According to NASA it contains 30 times more CO2-ice than initially presumed. It has major difficulty kick-starting positive feedback loops.
Correction; we Skeptics live on planet Earth. Hard to say what planet (or even universe) Warmists live on.
It appears to be a restatement of the theory that Venus has periodically resurfaced itself volcanically. This is obvious to practitioners of science since Venus has no craters, or very few, compared to most of the moons and planets and asteroids in the Solar System.
In this case, the “impact erosion” knocked off the layer of earth which would have made it resurface itself with planet-wide volcanic floods, just like Venus:
They could be getting a little closer to the truth when they say that some of earth’s crust has been partly lofted into space. It would not surprise me if an occasional meteorite was actually a terrestrial rock returning to us; rocks from Mars are collected from Antarctica all of the time.
It is not really a very peaceful neighborhood here. You can make all the rules and models you want but the sun and asteroids are not always going to obey them.
This little bombardment knocked off the crust
This little bombardment deposited the ocean water
This little bombardment cleared the stage for mammals
And now we are all snug and safe except for the ghgs from agriculture, cattle, and personal transportation.
Not to mention the Squidgy Bombardment, which, in the Nebular Hypothesis, assembled the planets in the first place.
Venus, with a considerably denser atmosphere, incoming meteors/comets would get burnt up far more than they do here on planet Earth (or on the moon that has no atmosphere).
It may well be the case that most incoming material gets burnt up,, or breaks up into smaller parts so one may well not expect to see as much in the way of impact craters on Venus.
So it could well be the case that the lack of impact craters is not evidence for volcanic replenishment of the surface.
Where do they get these people????
Venus is the way it is because it has 96 times more atmosphere than Earth. The composition of that atmosphere is irrelevant! The ‘work’ done on that mass by gravity raises both the pressure and temperature of its atmosphere at its solid surface. This is standard physics. No other fairy tale explanation is needed. No greenhouse effect. Why is this so hard to understand?
Because it’s wrong!
Show me your equations .
See
“Don’t Tell the Experts”
and the original 2010 article
“Venus: No Greenhouse Effect”
I don’t see anything other than the most basic Stefan-Boltzmann relationship which will produce the 328k gray body temperature in Venus’s orbit . I don’t even see the equations for the dependence of radiative balance on spectrum ( color ) .
I see no equations for any additional parameters .
Bob,
What additional parameters do you need and why ?
The observed, measured ratio is enough to make the point is it not ?
Any of those factors which are a function of radius .
Dear Moderator, this comment seems to have been lost?
hockeyschtick Your comment is awaiting moderation.
July 22, 2015 at 7:19 pm
No, it is not wrong. Mathematical derivation of equations which perfectly describe temperature profiles of Earth, Venus, Triton, & all other planets in our solar system with thick atmospheres:
http://hockeyschtick.blogspot.com/2015/07/new-paper-finds-increased-co2-or.html
Same basic atmospheric physics were used to calculate the 1976 US Standard Atmosphere, without one single radiative transfer calculation, and entirely on the basis of mass/gravity/pressure/density. Trace CO2 was completely discarded from their model since it was determined to have negligible effect.
http://hockeyschtick.blogspot.com/search?q=1976+US+Standard+Atmosphere
I’ll have to study your links . While clearly there is a gravitational energy well to a planet , it intuitively seems far too little to account for the temperature gradient of Venus . In deed , Venus and Earth are very different in the manner in which they are heated . The Earth is , of course heated from the surface causing strong convection . Only about 3% of impinging solar energy reaches Venus’s surface . Thus in a first approximation the effective surface at which radiative balance between its spectrum as seen from the outside and that of the sun is high in the very reflective clouds . Within that boundary the divergence theorem says average energy density will match that calculated for that surface .
Unfortunately it will be some time before I look at these equations because my priority is bringing my open 4th.CoSy APL informed vocabulary in Forth to the point where I can express your equations as succinctly as you have written them so they will run on arbitrary data on any current or future hardware .
Incidentally , Alan Guth has a brief but convincing explanation of why gravity is a negative energy in a short appendix in his book The Inflationary Universe . It is appealing that the sum of gravitational and thermal energy is the quantity which is balanced . Perhaps that is what your equations do .
Bob,
It isn’t just the movement up or down in relation to the pull of gravity. For gases it is also the extent to which the gas molecules move closer together or further apart under the gravitational influence as they rise or fall relative to the centre of gravity.
That is where the bulk of the mechanical KE to PE or PE to KE exchange comes from.
When you bring that into the equation the temperature of the Venusian surface is fully explainable.
I will be looking at Hockey Schtick’s links when I have time . He provides equations .
But my priorities are my ( approximately ) MidSummer party the first Saturday in August ( anyone along the Front Range is welcome ) and some recursive “stack frame” vocabulary to enhance my 4th.CoSy‘s ability to express such equations and apply them over a sphere .
Bob, see my comment: http://wattsupwiththat.com/2015/07/22/why-we-live-on-earth-and-not-venus/#comment-1992058
Because it is wrong. Work is done on mass by gravity only when it changes height. Gravitational compression can indeed be a source of “heating” — in a gravitationally collapsing protostar, or maybe even in star-wannabe Jupiter. Not so much for the Earth’s atmosphere. The adiabatic lapse rate is what you are trying to describe, and it isn’t maintained by the “work” done by gravity, it is the result of the adiabatic expansion and compression of air that is uplifted or downfalling due to ordinary convection, due to buoyancy. And that in turn is caused by heating or cooling of the gas by something else, not by gravity.
Gravity is not a source of energy for the atmosphere. It is a bank where energy from other sources — almost entirely from the sun, ultimately — can be stored and recovered. But the source of atmospheric heat is pretty much The Sun.
rgb
rgb said:
“Gravity is not a source of energy for the atmosphere. It is a bank where energy from other sources — almost entirely from the sun, ultimately — can be stored and recovered”
Gravity itself is not the ‘bank’ because gravity has no ‘substance’ which can carry such banked energy.
Instead the ‘bank’ is atmospheric mass which, when lifted up within a gravitational field stores what was previously heat in the form of kinetic energy as potential energy which is not heat.
That kinetic energy is then recovered in the subsequent descentt.
The recovered kinetic energy in descent cannot warm the surface directly but instead reduces convection beneath the descending column which allows continuing insolation to heat the surface beneath higher than S-B predicts.
The additional kinetic energy at the surface cannot then be radiated to space because it immediately gets taken up in the next cycle of convective uplift.
The same parcel of kinetic energy at the surface cannot simultaneously be radiated to space AND engaged in maintaining the hydrostatic balance of atmospheric mass suspended off the surface against the force of gravity.
Energy cannot be in two places at once or perform two distinct processes at once.
“That kinetic energy is then recovered in the subsequent descent”
…
Oppps….
…
You forgot something.
…
Whenever some air rises due to heat, there is an equivalent volume of air that has to descend to take it’s place.
Joel,
That is implicit in my account.
Once the first convective overturning cycle completes, a quantity of stored PE is then locked permanently into that cycle and cannot escape to space.
From then on all KE taken up from the surface is matched by KE returning to the surface in a never ending loop and that is why the surface is warmer than S-B. No GHGs needed.
RGB seems to think that the relevant PE is simply the sort of PE stored by lifting a solid or a liquid up against gravity which is a relatively small figure.
Since gases are far more compressible than solids or liquids the PE that they acquire during uplift is mostly derived from the molecules moving apart rather than from the mere uplifting of their mass against gravity.
As the gas molecules move up into a region of lower pressure the moving apart takes up energy in the form of PE and in the process reduces the vibrational activity of each molecule which results in a reduction of KE and thus cooling.
Gases which decrease density always bcome cooler (vibrating less) and gases which increase density always become warmer (vibrating more)
It is the relationship between density and molecular vibrational activity which is most relevant rather than simple height above the surface. This is a special feature of gases which is why we need The Gas Laws.
“a quantity of stored PE is then locked permanently into that cycle and cannot escape to space.”
….
I don’t think that is correct. The effect is a zero sum game. The energy used to move mass up is recovered in the heating due to compression of the downward moving air that replaces the volume in the updraft.
Joel,
It is only a zero sum game after the first convective overturning cycle completes.
At that point just as much energy is taken upwards as is returned downwards in a never ending loop for as long as the atmosphere remains suspended off the surface.
During the first convective cycle the energy taken upward was drawn from radiation leaving to space so from space the Earth would temporarily appear to be at 255K less 33K = 222K.
At the end of that first convective cycle the Earth from space would settle at 255K but you still have that extra 33K (or whatever) sitting at the surface holding the mass of the atmosphere off the surface in hydrostatic balance.
rgb says gravity doesn’t do thermodynamic Work on Earth’s or the Venutian atmosphere (due to adiabatic compression/expansion). Sorry, but this contradicts basic atmospheric physics known at least since Maxwell’s 1872 book Theory of Heat, and which proposed the basis of the barometric formulae, Poisson relation, and the 33C gravito-thermal (not radiative) GHE. Here’s slides from a basic atmospheric physics course that explain Work done by gravity via adiabatic compression/expansion:
http://hockeyschtick.blogspot.com/search?q=adiabatic+work+thermodynamics
See also:
http://hockeyschtick.blogspot.com/2014/11/the-greenhouse-equation-predicts.html
Joel said:
“There is a significant difference between the environment at 1 atm pressure on Venus versus 1 atm pressure on Earth”
Why is that ‘significant’ if temperature and pressure are similar at 1 atm ?
That simple fact shows that it is atmospheric mass and not radiative characteristics which controls temperatures and pressures within planetary atmospheres.
Other features of the surrounding environment are irrelevant.
The only factors that influence surface temperatures are atmospheric mass, the strength of the gravitational field (which controls surface densitry) and the prortion of top of atmosphere insolation absorbed by both surface and atmosphere by conduction and convection.
Any radiative imbalances that develop are dealt with by convective changes that prevent surface temperature changes.
For a detailed explanation as to how that works see here:
http://hockeyschtick.blogspot.co.uk/2015/07/erasing-agw-how-convection-responds-to.html
The second diagram is especially pertinent.
“Why is that ‘significant’??
…
Simple.
…
On earth there is a solid/liquid surface below the 1 atm point. There is no such surface on Venus at that altitude.
…
Inbound radiation behaves differently when it hits the solid/liquid surface at 1 atm on Earth as opposed to the transparent volume beneath the 1atm altitude on Venus.
“Inbound radiation behaves differently when it hits the solid/liquid surface at 1 atm on Earth as opposed to the transparent volume beneath the 1atm altitude on Venus.”
But yet it makes no difference to the relationship between temperature and pressure which rather proves my point 🙂
Convection adjusts to correct for any radiative imbalances.
” But yet it makes no difference to the relationship between temperature and pressure ”
…
The relationship breaks down at the 1 atm level.
…
Any pressure higher than 1 atm makes the comparison between Earth and Venus invalid.
Still confused about the adiabatic lapse rate I see.
Maintained by gravity. An upward moving gas molecule loses speed, and thus temperature, to gravity. A downward moving molecule gains speed and thus temperature.
Correct.
If radiative characteristics serve to introduce a radiative equilibrium then convection changes to negate it:
http://www.public.asu.edu/~hhuang38/mae578_lecture_06.pdf
The proof is that the temperature and pressure within the atmospheres of both Earth and Venus (and other planets) is similar after adjusting for distance from the sun.
Harry Dale Huffman’s calculation is correct and he cannot be discredited on that point just because one might disagree with him on other points.
Harry Dale Huffman’s calculation is incorrect due to a massive problem in his thinking. There is a significant difference between the environment at 1 atm pressure on Venus versus 1 atm pressure on Earth. Below the altitude of 1 atm on Venus there is a lot of atmosphere where radiant energy can dissipate, many km of additional CO2. On Earth below the 1 atm point there is solid surface. You cannot compare the two because it is an “apples to oranges” comparison.
Joel D Jackson: The point is that the *overlapping* portions of the T/P curve are very similar between Earth & Venus, despite huge differences of atmospheric composition. True for all the other planets with thick atmospheres in our solar system as well (Robinson & Catling in Nature). Magellan mission shows T/P curve very close to Earth’s 1976 US Std Atmosphere overlapping portions, & US Std Atm completely excludes CO2 & radiative calculations from their model.
I’ve been aware of it being standard physics since schooldays in the mid 20th century. Only in recent years as it been ignored and replaced with the defective radiative theory of gases.
I think that the importance of the Earth’s magnetic shielding from the solar and cosmic rays radiation is grossly underestimated.
Where did they get the idea that the early earth’s crust was full of transuranics? Being heavier, those elements would have mostly sunk to the core while the earth’s surface was still molten.
This alleged bombardment erosion would have affected all of the inner planets.
The reason why the earth has a thin crust is that a Mars sized planet crashed into the earth some 4 billion years ago. The collision ejected most of the crust which formed the moon.
The two cores combined giving us a larger than average core, combined with a thinner than average crust.
That impact erosion theory is not likely. What distinguishes us from Venus is plate tectonics: we have it but Venus does not. With active plate tectonics radioactive heat is constantly vented by plate boundary volcanism. Absent plate tectonics, heat just piles up beneath the crust. In-plate volcanoes form and excessive heat eventually so weakens the crust that it breaks up into giant slabs. These sink into the interior and an entirely new crust is created. Its atmosphere is a product of these giant volcanic eructations and not a result of an ocean boiling away as some climate scientists like Hansen have hypothesized. On Venus impact craters are not eroded and from crater counts it has been determined that the existing crust is no more than 500 million years old. It is likely that these repaving incidents happen every 300 to 600 million years on Venus. If it is the same age as the earth there may have been as many as eight or ten such episodes in its past.
Venus is not so dissimilar from Earth as it looks on first sight. Just strip Venus atmosphere from CO2, imagine it as storing it to limestone CaCO3… Look what will remain:
16800x10e15 kg of N2 (Earth 4270x10e15kg), 72x10e15kg of SO2, 33.6x10e15 of Argon (Earth 47x10e15), 9.6x10e15kg of water (Earth 1400000x10e15kg), 3.4x10e15 kg of Neon.
Mass of water comparing to Earth seems minuscule, but it is enough to cover whole Venus with 21cm deep ocean.
Let’s assume that Nitrogen/Oxygen ratio will remain same as on Earth 78/21% and some Oxygen remains in atmosphere. It will be 4523x10e15kg (21/78*16800)
Result will be total mass of atmosphere 21432x10e15kg (Earth 5500x10e15kg) with percentual content:
78% N2
21% O2
0.3% SO2
0.1% Ar
0.01% Ne
So we have 4 times more dense atmosphere than on Earth, with almost same composition and some water to run hydrological cycle.
I think only problem of Venus is missing life which did not strip Venus atmosphere of CO2 and stored it as limestone and Carbon.
Sublime.
I don’t completely disagree with this, but I think the much more dense atmosphere also created the surface temperatures that made life capable of stripping out CO2 and reducing it to oxygen and not just limestone but other forms of sequestered carbon comparatively unlikely. I’m guessing its comparative dearth of water made a big difference as well — both because life probably requires free water or even free ice to start up (which in turn requires certain pressure/temperature ranges) and because oceans are enormous thermal sinks. The Earth’s ocean acts like an anti-greenhouse — 4 C on the bottom almost everywhere, warmer in only a very thin layer at the very surface (where even that is warmer). That’s the funny thing. At least 60%, maybe closer to 70%, of the actual surface of the Earth is at or very close to 4 C in temperature. If one averages the temperature over the mass of the fluid components of the Earth’s surface, I suspect that they are collectively much colder than 288 K. Even the land surface rapidly approaches the 10 to 14 C temperature that is supposedly the average once you dig below the surface — ten feet or more down, it is usually cave cool, and remains quite cool until you descend far enough to begin to experience the effect of insulation and switch from surface heating to heat flowing out of the interior as a primary source.
It sounds like Venus is remarkably hot everywhere in its interior, given its surface temperature.
If we had the money and the will, we could certainly do some very interesting things with Venus. The most interesting one would be to try to block sunlight from Venus altogether for a year or two. Try to cool it to where the CO_2 rained out on the surface, chilling it down but good. See if doing this would freeze it deep enough to develop a real crust, one that would last when the screen was removed. Partially remove the screen, let it develop (say) 1 atm of pressure, and see if one could get plants established that would fix the carbon and liberate the oxygen while letting it gradually warm. Drop a few dozen comets on it to bump up the water. Install a huge solar powered laser in orbit that is aimed to blow off its atmosphere (give it escape speed at the top) and run it for a few centuries to see if one can strip it down. Terraform the place!
It isn’t any more of a waste of money than carbon trading, and there is a whole world to reclaim if one can make it work. Mars would be fun to work on as well, but there the difficulty would be getting the raw materials for an atmosphere and (if possible) bumping up its mass so that it would last. One would have to drop whole moons into it and wait a few million years for it to cool down. Venus seems as though it could be a much faster project.
rgb
I find the closeness of the 277+ deep ocean temperature to the 278+ gray body temperature in our orbit an interesting datum .
A strong prima facie indication that Venus’s internal heat dominates is that its surface temperature appears to be nearly uniform over the whole sphere despite its year long day .
Bob,
venus has an effective gb T of only 188K vs 255K for earth. Thats because its bond albedo is 0.90 already. It’s at 3/4 the orbital diameter of earth so the tsi is somewhat more but that albedo has a massive effect. you have some interesting terraforming notions but the biggest buggaboo is that rotation rate. no rotation – no magnetic field. it’s doubtlessly extremely hot inside and capable of one – if it could only spin up. trying to blow off the atmosphere from a big laser – cut idea – assuming it doesn’t launch itself outa orbit by it’s own beam but with no spin – the atmosphere is no mixed well vertically. it’s basically an ocean of co2 at the bottom and nearly 2 (earth) atmospheres of n2 floating on top – so you’d blow away the n2 before you ever made a dent in co2.
seems like pretty much a lost cause – better to colonize the asteroid belt, moon, and mars before wasting effort on venus. even mercury might be effort better spent. besides, in the long run, we need to get further away from that warming sun and when it finally goes, venus is going to be inside.LOL
I’m sorry , but those are such irrelevant BS numbers . Doubly so if “gb” stands for “gray body” .
The gray body ( flat spectrum ) temperature in Venus’s orbit is about 328k .
If you want to discuss any other value , give me a measured full absorption=emission spectrum for the planet and I will tell you its radiative balance temperature .
feel free to go check out the nasa fact sheet on venus. you’ll find its temperature at 184.2k
rgb said:
“It makes it 33 warmer than the greybody temperature, which is not exactly S-B. It isn’t “mass” per se that does it, either — it is atmospheric density, the adiabatic lapse rate, and greenhouse gases all working together that does it. ”
You don’t need greenhouse gases to do it.
Even without GHGs gravity works with mass to produce declining density with height. It is that decline in density with height that allows uneven surface heating (causing density differentials in the horizontal plane at the surface) to result in lighter less dense parcels of air rising above heavier more dense parcels.
Convective overturning inevitably ensues with no need for GHGs. There can be no isothermal atmosphere developing as long as there is uneven surface heating (inevitable around a sphere illuminated by a point source) and a decline in density with height.
Reducing density with height creates the lapse rate slope because work is done against gravity in lifting atmospheric mass and that converts KE at the surface to PE above the surface for a cooling effect.
The process is reversed in descent.
This is basic meteorology which is a specialised discipline from which one can learn that rising columns of air develop huge reserves of potential energy (PE).
Agreed with Stephen, including “you don’t need GHGs to do it,” and that a pure N2/O2 atmosphere would establish a GHE/temperature gradient (even greater than current atmosphere – calculations in my links above).
Maxwell, greatest physicist in history on the topics of heat & radiation said in his 1872 book Theory of Heat that the atmospheric temperature gradient (GHE) is due to dominance of convection over radiative-convective equilibrium, & atmospheric temperatures a function of pressure raised to a ratio of specific heat capacities. Carnot & Clausius also described the essentially the same gravito-thermal GHE.
Basically we are here because we are here, the odds are like drawing 4 of a kind 4 hands in a row, but it happened. With billions of stars it’s likely life started else where as well. I’m mean we have creatures at the bottom of the ocean.
In our solar system having 1 planet with life is incredible, not everyone gets 4 of a kind 4 hands in a row in 5 card stud.
No, it is not wrong. Mathematical derivation of equations which perfectly describe temperature profiles of Earth, Venus, Triton, & all other planets in our solar system with thick atmospheres:
http://hockeyschtick.blogspot.com/2015/07/new-paper-finds-increased-co2-or.html
Same basic atmospheric physics were used to calculate the 1976 US Standard Atmosphere, without one single radiative transfer calculation, and entirely on the basis of mass/gravity/pressure/density. Trace CO2 was completely discarded from their model since it was determined to have negligible effect.
http://hockeyschtick.blogspot.com/search?q=1976+US+Standard+Atmosphere
This illustrates how climate science works, we have three things; what is, what isn’t and what might be. Every statement about greenhouse warming has to be qualified by “than it would have been” and how do we know how hot it would have been. The atmosphere of Venus is mostly carbon dioxide which is a greenhouse gas so why would it not have some effect on temperature as well as atmospheric pressure. If we were to take water out of earths atmosphere then it would seem to me that we would end up with a dessert climate where it was hot during the day but cold at night it would only be uniformly hot if we had the atmospheric pressure of Venus.
A dessert climate?
Must be Baked Alaska!