In the New York Times:
For science that’s accessible but credible, steer clear of polarizing hatefests like atheist or eco-apocalypse blogs. Instead, check out scientificamerican.com, discovermagazine.com and Anthony Watts’s blog, Watts Up With That?
Of course, we can’t have that, now the howling begins. Some context below.
More from the New York Times Virginia Heffernan:
Clearly I’ve been out of some loop for too long, but does everyone take for granted now that science sites are where graduate students, researchers, doctors and the “skeptical community” go not to interpret data or review experiments but to chip off one-liners, promote their books and jeer at smokers, fat people and churchgoers? And can anyone who still enjoys this class-inflected bloodsport tell me why it has to happen under the banner of science?
Hammering away at an ideology, substituting stridency for contemplation, pummeling its enemies in absentia: ScienceBlogs has become Fox News for the religion-baiting, peak-oil crowd. Though Myers and other science bloggers boast that they can be jerky in the service of anti-charlatanism, that’s not what’s bothersome about them. What’s bothersome is that the site is misleading. It’s not science by scientists, not even remotely; it’s science blogging by science bloggers. And science blogging, apparently, is a form of redundant and effortfully incendiary rhetoric that draws bad-faith moral authority from the word “science” and from occasional invocations of “peer-reviewed” thises and thats.
Under cover of intellectual rigor, the science bloggers — or many of the most visible ones, anyway — prosecute agendas so charged with bigotry that it doesn’t take a pun-happy French critic or a rapier-witted Cambridge atheist to call this whole ScienceBlogs enterprise what it is, or has become: class-war claptrap.
This is all about Pepsigate. See Heffernan’s column The Medium
h/t to Tim Lambert of Deltoid, hosted by Scienceblogs who couldn’t bring himself to reference anything else here at WUWT with his collection of supposed gotchas, only the one point where he was sure he could get a dig in:
Heffernan reckons that Whats Up With That presents credible science. This is a blog that argues that Venus is hot, not because of the greenhouse effect, but because of the high pressure in the atmosphere (so hence Jupiter and Saturn are the hottest planets right?) . Look:
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
Only if there was no such thing as gravity.
Umm, Tim, can you tell me what gases on Venus remain in a non-solid state at temperatures approaching absolute zero? What happens to solidified gases like dry ice (Frozen Carbon Dioxide) in a (planetary) gravitational field? Here’s an experiment to help you get the answer:
1. Acquire some dry ice
2. Go outside
3. Toss it upwards into the atmosphere
4. Observe
The point that was being made in that article by Goddard is that with no external energy source (the Sun) Venusian atmospheric gases would contract and eventually freeze at near absolute zero and cling to the surface of the planet, thanks to gravity.
PhysLink agrees:
Question
What will happen to the gas at absolute zero temperature (0 K)?
Asked by: Rohit
Answer
First of all, the gas will no longer be a gas at absolute zero, but rather a solid. As the gas is cooled, it will make a phase transition from gas into liquid, and upon further cooling from liquid to solid (ie. freezing). Some gases, such as carbon dioxide, skip the liquid phase altogether and go directly from gas to solid.
…
First off, 0K can never be achieved, since the amount of entropy in a system can never be equal to zero, which is the statement of the second law of thermodynamics. This can be nicely illustrated by your question:
Using the state equation for an ideal gas:
PV = nRT
T, the thermodynamic temperature will be equal to 0, so the product of the molar gas constant R (8.31 J/mol/K) and the amount of moles n, will also be zero.
Therefore the product of PV must be zero also. the pressure of the gas must be zero or volume of the gas must be zero
As an example, look at the Ice Caps of Mars, still well above absolute zero but below the freezing point of Carbon Dioxide:
From Wiki:
The polar caps at both poles consist primarily of water ice. Frozen carbon dioxide accumulates as a thin layer about one metre thick on the north cap in the northern winter only, while the south cap has a permanent dry ice cover about eight metres thick.[62]
As we see in the Physlink description, a planetary wide near absolute zero temperature (if the sun blinked off), all the rest of Mars atmosphere would be bound to the surface as a solid too. The result: no atmosphere and no atmospheric pressure.
UPDATE: As is typical anytime somebody not on the team that gets a voice or mention, those who deal in mudslinging and angry rhetoric swarm in to squash it and convince the writer of the “wrongness” of it all.
Here’s a comment from Virginia Heffernan after she’s had the treatment here. Note the number of angry labels preceding her response.
Virginia Says:
I’m grateful for all the replies. Nice to meet you here, David.
I get the sense that Pepsigate was the last straw – or not the first, anyway – for at least some of the dissenters from ScienceBlogs. Out of curiosity: Did no one quietly resign over PZ Myers’s Mohammad cartoons? Or question whether they wanted to be part of a network to which he’s the main draw?
In my experience, legacy media types, who do kick up furors over stuff like Mohammad cartoons, nonetheless see *debate* over ad-ed breaches as common, especially now because of the confusion what old-media road rules mean in digital times.
With notable exceptions, blogging, as a form, seems to me to have calcified. Many bloggers who started strong 3-5 years ago have gotten stuck in grudge matches. This is even more evident on political blogs than on science blogs. In fact, after being surprised to find the same cycles of invective on ScienceBlogs that appear on political blogs (where they’re well documented), I started to think the problem might be with the form itself. Like many literary and art forms before it (New Yorker poetry, jazz, manifestos) blogs may have had a heyday – when huge numbers of people were inspired to make original contributions – before, seemingly all at once, the moment is gone. Some people keep doing it, and doing it well, but the wave of innovation passes, and the form itself needs new life. (Twitter? Tumblr?)
I have no training in science. My surprise at ScienceBlogs was akin to the surprise a scientist who might feel if he audited a PhD seminar on Wallace Stevens. Why aren’t they talking about “Anecdote of the Jar”?! Why are they talking about how “misogyny intrinsic to the modernist project”? I saw political axe-grinding bring the humanities almost to a standstill in the 1990s. I thought science was supposed to be above that!
One regret: the Watts blog. Virtually everyone who emailed me pointed out that it’s as axe-grinding as anything out there. I linked to it because has a lively voice; it’s detail-oriented and seemingly not snide; and, above all, it has some beautiful images I’d never seen before. I’m a stranger to the debates on science blogs, so I frankly didn’t recognize the weatherspeak on the blog as “denialist”; I didn’t even know about denialism. I’m don’t endorse the views on the Watts blog, and I’m extremely sorry the recommendation seemed ideological.
All best,
Virginia Heffernan
Jupiter is the hottest planet, due to the extremely high atmospheric pressure and radioactive decay. Is this Lambert guy for real?
http://www.nasa.gov/worldbook/jupiter_worldbook.html
Well I want to thank you, I’ve been following your photos of thermometers for NOAA for some time.
Tamino censored my response to his article, which included these two phase diagrams, showing that pressure approaches zero as temperature approaches zero.
http://encyclopedia.airliquide.com/images_encyclopedie/VaporPressureGraph/Helium_Vapor_Pressure.GIF
http://www.atmos.washington.edu/2003Q3/101/notes/SaturationVaporPressure3.gif
Venus is hot not because of a greenhouse effect, per se, but because the atmosphere is optically thick — which amounts to almost the same thing as “pressure is high.” The same seems true of Saturn and Jupiter, so Lambert’s mocking tone is off target. Each of these planets achieves an equilibrium temperature appropriate to their distance from the sun at a level well up in the atmosphere (Earth does so essentially at the ground surface which provides most of the warmth for its atmosphere). However, enough energy continues on toward the ground (or to lower levels in the atmosphere) to mix the atmosphere vertically. Adiabatic heating results in temperatures lower in the atmosphere that are surprisingly high. I think both Jupiter and Saturn have lower atmospheric temperatures that are quite high considering distance to the Sun.
Arguments in natural science are often very complex, or at least they involve cascades of mechanisms, which provides all sorts of opportunities for mischief from “gotcha” sorts of people.
Your own reference says “the pressure of the gas must be zero or volume of the gas must be zero” and from this you conclude that the pressure must be zero?
In any case, absent the sun, temperatures don’t go to absolute zero — cosmic background radiation is 3K. An ideal gas (which is what Goddard’s equation describes) remains a gas at any temperature. And the pressure remains the same.
[he said near absolute zero not absolute zero. 3K would certainly qualify as “near”. And does a solid have atmospheric pressure? Also “Goddard’s equation” is in fact the ideal gas law. This is not of his making. see http://www.ausetute.com.au/idealgas.html
~mod]
Is Lambert some sort of scientist? If he is, I have a safety tip: Do not hire this clown. He combines ignorance with stupidity to a startling degree.
The Times is one of the most perniciously writtem caviar-left rag. One line out of three is a very serious insult to intelligence and pretty much any other is a mild one too. I cannot read it without a bucket nearby to vomit in.
The only reason I open the Times is to see which corporations have the indecency to advertise in it’s pages and to try my best to avoid patronizing those advertisers.
Its seems as the political thought content increases, the critical thought content approaches zero.
Jupiter is the hottest planet, due to the extremely high atmospheric pressure and radioactive decay. Is this Lambert guy for real?
What is the temperature of Jupiter at the altitude at which the pressure is roughly equal to earth’s pressure at ground level?
Here some thoughts on”the Venus argument” in the climate debate:
http://hidethedecline.eu/pages/posts/rdquovenus-argumentrdquo-the-5.php
Tim Lambert
You clearly did not read or understand my article, and quoted one equation you did not understand out of context.
Tim Lambert said- “(so hence Jupiter and Saturn are the hottest planets right?)”
Hahahaha. Oh, wait.
Here are some widely-available data on Jupiter:
The adiabatic lapse rate of Jupiter’s 5000 km thick gaseous phase atmosphere (hydrogen, helium, trace amounts of methane, other bits) is about 2 K/km.
The temperature at 1 bar of pressure on Jupiter is about 165 K. But that is a looooong way from the surface. Jupiter’s distance from the sun is about 5 times Earth’s distance. The 1/r^2 drop in solar insolation, a factor of 25, results (for the same albedo) in a predicted absolute temperature about 2.2 times lower than for Earth at 1 bar (assuming Blackbody equilibrium with no internal heat sources). Earth is about 280 K, so really simple estimates give about 125K at 1 bar on Jupiter-in the ballpark.
At 100 km down into the Jovian atmosphere, T=300K and P=10 bar.
At 20,000 km down from the top of the atmosphere, an ocean of metallic hydrogen begins, with T=11,000K and P=3,000,000 bar.
At 60,000 km down from the top of the atmosphere, a rocky surface is thought to exist, with T=25,000K and P=12,000,000 bar.
It appears that the corresponding ‘surface’ of Jupiter is either at the metallic hydrogen transition region (ocean-like), or the surface of the rocky core. The former has T=11,000K, and the latter has T=25,000K.
So, Jupiter is just a smidgen hotter than Venus or Mercury or Earth or Mars or Saturn or Uranus or Neptune or protoplanet Pluto.
Huh…
…”the “skeptical community” go not to interpret data … but to … jeer at smokers, fat people and churchgoers?”
Is there no end to the twisted hypocrisy of warmist accusations?
Jeer at smokers? I thought realists were the 40-a-day chuffers supposed to be denying the links to cancer?
Jeer at fat people? I thought the deep green Malthusian Optimum Population Trust had the monopoly on seeking to tax large framed individuals more because of their over-consumption?
Jeer at churchgoers? Last I read, realists were painted as creationists.
Here was me thinking that it was those self-righteous, sanctimonious, intolerant libtard hypocrites that were sledging smokers for killing them with their second-hand smoke, complaining that their airplane tickets should be cheaper than the fullsome individuals seated along-side them and getting utterly hysterical that their daughter came home from primary school to tell them that she heard there was a God. How wrong I was! All along, it wasn’t the cultural Marxist atheists who embraced the intolerance of eco-fascism. Virginia Heffernan has opened my eyes to my own Lysenkoism, gah, I’m a beaten man.
Anthony quotes Tim Lambert as writing:
“Heffernan reckons that Whats Up With That presents credible science.”
Surely this is not the issue that Hefferman was writing about. Surely Hefferman was not criticizing all science blogs for not presenting only peer-reviewed material. Maybe she was criticizing some science blogs for claiming that they are presenting the scientific truth in all matters they discuss. I don’t think so. I think she was criticizing bloggers for using the good name of science to carry on their various bigoted agendas which have nothing to do with science. Clearly, WUWT has no hidden agendas, bigoted or otherwise. I do not think that Hefferman intended criticism of WUWT. I think Lambert misunderstood Hefferman. In any case, the point of criticism that Lambert introduced is clearly taken out of context, and that context has been supplied already on WUWT. Case closed.
The “ideal gas” only makes sense if the gas is “thin” (the volume of the molecules does not matter and there is no force between them). If one gets near the condensation point, one should use as a better (but more complicated) formula the one by Van der Waals.
” stevengoddard says:
July 31, 2010 at 8:55 am
Is this Lambert guy for real?”
Is this the same guy who used a fake tape in a debate with Monckton?
” Tim Lambert says:
July 31, 2010 at 9:18 am
Also “Goddard’s equation” is in fact the ideal gas law.”
Actually, the “ideal gas” is not a law, but one of the best examples of a model. One assumes that molecules are points with no volume or interaction (but with mass), that pressure is the continuous collision of these molecules with the walls, uses classical mechanics and some statistics, and one gets what can be used as a definition of temperature.
Of course, for Boyle and Mariotte what they found felt very much like a law.
Steven,
first of all there can be considered Kelvin–Helmholtz mechanism. But there is a limitation due contraction time of the planet. Secondly the Jupiter can be assumed to be a white dwarf with its mass-radius relationship. So its core will be hot for a very long time 🙂
Wow Tim, calm down, you sound like my 3 year old daughter does just before she gets sent to the naughty chair.
It may be important to explain why Venus is so hot now, but what I want to know is where did all the water on Venus go, why is there an excess of deuterium in the atmosphere, and where did all the CO2 come from?
Here is one diagram of the Jovian atmospheric profile. Take it for what it is – we need to do more exploration.
http://www.windows2universe.org/jupiter/images/J_temp_profile_gif_image.html&edu=high
Alexej Buergin sayJuly 31, 2010 at 10:04 am :
Actually, the “ideal gas” is not a law, but one of the best examples of a model. One assumes that molecules are points with no volume or interaction (but with mass), that pressure is the continuous collision of these molecules with the walls, uses classical mechanics and some statistics, and one gets what can be used as a definition of temperature.
As anyone who has dealt with compressed gasses knows, they diverge from the ideal gas law due to their different compressabilities.
Tim Lambert said: “Here’s the thing. Science works. Antibiotics work. And we know they work not because of any “bad-faith moral authority” by scientists but because they collected evidence and conducted experiments and drew conclusions that survived review by their peers.”
Actually no, Tim. We know they work because the results are reproducible by other scientists. Peer review tells you very little about the quality of the science.
You say that “science works”, but that is not always the case, as with climate science. In that instance, and possibly others, the scientific process has been subverted. “Peer review” has become nothing more than an automatic rubber- stamp for any “science” in support of the manmade warming/climate change ideology. It is simply “Pal review”. CAGW/CC has become an industry, and those employed by that industry will do anything in their power to keep it going. Going against it could have seriously negative consequences for one’s standing and career.
Congratulations, Anthony, for the favorable mentioning in the NYT.
Bob, the CO2 comes from volcanoes, just as Earth’s CO2 did.
Rubbish from a journalist who makes up words.
He could at least hit the spell-check button before submission.
Perhaps a couple of fact-checks here and there….
They’re still masticating the subject of Pepsigate??!!
I would have thought that by now the subject would have been thoroughly chewed, swallowed, digested and expelled into the proper receptacle worthy of such pompous self-righteousness. And as for getting a h/t from the NYT — oh well, about what’s to be expected from the lamestream media where it’s better late than never. I don’t expect you’ll see a surge in traffic from the mention. Heck, that article in the NYT will probably get more hits than normal, thanks to your mention of it here!
” Robert of Ottawa says:
July 31, 2010 at 10:23 am
As anyone who has dealt with compressed gasses knows, they diverge from the ideal gas law due to their different compressabilities.”
Right, and that can be “explained” by the fact that molecules do have a volume (that cannot be compressed, at least not according to the Van der Waals model) and they do attract each other (which makes the pressure on the walls smaller).
WAAAAAAAAATTS!
Easing people into reality is probably the more humane thing to do as the NYT is trying.
Many people accept changes in their perception of reality more easily than others. But imagine you are a major celebrity or VIP who has had hard and fast beliefs in a particular ideology and has been trumpeting that belief a long time. Just think of how big a blow to your ego it is when that steadfast belief is confronted by an alternate explanation in opposition to your ideological belief? Your first reaction is to confront the anathema to your ego with the power of your ego. Unfortunately, your ego is not more powerful than the SUN. Eventually you come to that realization and feel the despair of your own shortcomings. It’s not easy.
Psychological affects of changes in mind are uncomfortable to people and we should have some sympathy to those soles, offer comfort, and let them know we still care about them.
NYT is at that crossroads again. Watch for more criticism of CAGW. When Dr. Goddard whose name graces NASAs space studies institution (any relation Steve?) did his rocketry work beginning back in the 20s with the belief that one day we would be able to travel in space, he had an idea of putting a gunpowder/oxygen payload on a rocket to the moon that would give a visible flash to telescopic viewers to record that the moon had been reached (television was already invented in 1926 but it was a curiosity that required another 20 odd yrs to come to fruition – need for networks, etc). NYT in particular ridiculed Goddard’s nutty idea. I would guess that in the climate debate, we are at the post sputnik I-type stage in the evolution of NYT’s thinking on the subject.
Given the source, the quote on jeering at fat people, smokers, and churchgoers is laughable hypocrisy at best. I would be honored to be insulted by the NYT.
Steve Goddard’s statement is correct, but it was incorrect to cite the ideal gas law as the justification for it – unless it was to indicate that the relationship obviously had to break down because it was intuitively obvious that the volume could never go to zero.
Tim Lambert managed to find the only 6 characters that were incorrect, and draw a conclusion that would only follow if they were true. An ideal gas would maintain a constant pressure (the weight of the atmosphere divided by the surface area of the planet) and *zero volume*. Ideal gases can do this because they’re assumed to be point particles and perfectly non-stick.
So Tim managed to treat the only bit that was wrong (the citing of the ideal gas law) as if it was true, and thereby concluded that the bit that was true (atmospheric pressure approaching zero) was wrong. Well done, Tim!
It seems the height of nitpickery to declare an entire website ‘unscientific’ on the basis of such a tiny, and somewhat ambiguous flaw. Science accepts that scientists make mistakes, and seeks to correct them. Science is an exploration of ideas. What matters – and decides whether you are “scientific” or not – is how you respond to it if a possible flaw is pointed out.
The ideal gas law works just fine. When you get below the freezing point the number of gas molecules (N) drops off rapidly so the pressure also drops off rapidly.
PV=NRT
When water freezes and becomes incorporated in the Greeland Ice Sheet, does Lambert still consider it part of the atmosphere? Does he think atmospheric pressure should be measured under two miles of ice?
Doh!
I have no training in science.
I could tell.
Bob asked where the CO2 came from on Venus. The answer is that the Vogons had a huge fleet of SUVs stationed there when the planet was more habitable. They happily and without thought drove them until the CO2 was a huge part of the atmosphere. The planet then heated up due to the greenhouse effect so that it got so hot all the lead/acid batteries in the SUVs exploded. The heat vaporized the sulfuric acid from the batteries making the clouds that now prevent us from seeing the surface of the planet. The Vogons, having been expelled from Venus decided to make a space bypass and are now awaiting approval of their permit to remove planet 3 in the system to unhinder the flow of traffic throughout the galaxy. If you have any complaints, they may be lodged at the local office in the Alpha Centauri system.
The moral of this story is that somehow we must stop Al Gore from releasing too much CO2 or the earth will be doomed. There appears to be direct relationship between the amount of his nonsense and his carbon footprint. If everybody follows his example, earth will be doomed sooner rather than later.
This information has been peer reviewed by my son who is standing right next to me and who will be thrown out of the house if he disagrees.
The NYT. A great paper for the liberal views. Many treehuggers rank it #1. A subscription is over 540 pounds of paper a year. Including trucking it to the reader, it is an environmental disaster. Deforesstation for getting the word out seems to not draw criticism.
My canary and I have many arguments on what goes to the bottom of the cage. It is disgusting what my canary does to the NYT headlines.
I am sure some one will blow a gasket over the NYT offering a courteous comment toward WUWT.
…..has become Fox News…..
She is political and “chip(ed) off one-liners” herself. 😉
Tim Lambert says:
July 31, 2010 at 9:18 am
In any case, absent the sun, temperatures don’t go to absolute zero
Did someone say that it did?
Jim Barker says:
July 31, 2010 at 9:27 am
Its seems as the political thought content increases, the critical thought content approaches zero.
Nice formula. Get your name on it, something like: The Barker Law.
joshua corning says:
“What is the temperature of Jupiter at the altitude at which the pressure is roughly equal to earth’s pressure at ground level?”
You could take the same question and apply to Venus. What is the temperature of Venus atmosphere at the altitude at which the pressure is roughly equal to earths pressure at ground level?
I would think it would be the combination of high pressure, distance from sun and slow rotation rate that leads to those extreme temperatures. I bet venus would be a very different planet if atmospheric pressure and rotational period was more earth like.
I never heard of this “Pepsigate” thing, apparently I skipped over that post. Now I think it’s one of the funniest things I’ve ever seen. I do believe in Karma, and this is an awesome example of it, even if those getting what they deserve don’t see it yet.
The “peer reviewed” “science” in nutrition and medicine is in just as bad shape as in climate issues, if not worse. I’d say Pepsico made a brilliant move in deciding to use the current state of “peer reviewed” “science” in order to promote their brands.
In the grand scheme of things, everything is bad for you in excess. I’m disgusted that I can’t get decent KFC anymore since they banned “transfats”, the potato chips and other snack foods I used to enjoy have pretty much all been destroyed and “sanitized” by junk-science compliance. When I microwave a bag of popcorn I always have to add some salt and usually some butter. Soups and other things I get from restaurants and even fast food places are so devoid of salt and fats that I seriously question how ANYONE can eat them.
There are foods that I used to eat as a child in the 60s and 70s that are either no longer available or have morphed into a mere shadow of their former glory. Children today are NOT getting proper, required nutrition during their critical growing phase, since they are being robbed of fats and sugars by well meaning but ignorant people.
Are people healthier? No.
Am I obese? No. The opposite, in fact.
I smoke, I drink, I eat fatty and salty foods, I don’t get a lot of exercise, and yet at 46 I do exceptionally well at all the traditional indicators of health: blood pressure, heart rate, endurance, strength, etc. Stick that in your “peer reviewed” junk-science food war record book.
To answer my own question…..
http://www.buzzle.com/articles/how-hot-is-venus.html
Kevin Kilty says:
July 31, 2010 at 9:08 am
“Venus is hot not because of a greenhouse effect, per se, but because the atmosphere is optically thick — which amounts to almost the same thing as “pressure is high.” ”
Yes, except that that’s pretty much what the planetary greenhouse effect is. A greenhouse works because the glass is “optically thick” (or thickish) to thermal radiation and convection currents from inside, while being “optically thin” (or less thick) to the sunlight from outside. Vertical convection is limited in the greenhouse by the physical barrier of the glass; in a planetary atmosphere its effectiveness is limited by the lapse rate. Except where there are clouds, the Earth’s atmosphere is not actually thick, but it is thicker for outgoing heat than for incoming sunlight, so the greenhouse effect, though weak, still raises the surface temperature above what it would be if the atmosphere were completely transparent to outgoing radiation.
“Each of these planets achieves an equilibrium temperature appropriate to their distance from the sun at a level well up in the atmosphere”
Oddly enough, seen from space, Venus is cold. The effective temperature at which Venus radiates is only ~230K, much lower than that of the Earth, despite the doubled top-of-atmosphere insolation. This is because the high albedo of the continuous cloud cover (~80%), which reflects away most of the sunlight. Without the clouds (but assuming the same optical depths) Venus’s atmosphere and surface would be ~50% hotter (up to ~1100K!) – which should make us realise how crucial clouds are in controlling the climate on Earth.
“Adiabatic heating results in temperatures lower in the atmosphere that are surprisingly high.”
It is not adiabatic heating, as such (that only happens where air masses sink, and is inevitably offset by the corresponding cooling of the equal and opposite rising masses). In the absence of any heat from below, or from sunlight penetrating to the lower levels, the atmosphere would be isothermal and very stably stratified. But even at the surface of Venus, enough sunlight penetrates (from memory ~9W/m2 – fortunately the exact figure isn’t important here) to raise the temperature to ~730K; the surface is cooled by thermal radiation, which however has a greater optical depth than the incoming sunlight (tau >~7.5 versus ~2.7, for assumed 9W/m2 at surface, or delta tau of >5 independent of actual surface flux). This temperature is at roughly the adiabatic limit for this atmosphere, so at least some of the cooling will be by convection (probably most).
“Arguments in natural science are often very complex, or at least they involve cascades of mechanisms, which provides all sorts of opportunities for mischief from “gotcha” sorts of people.”
Very true.
stevengoddard says: July 31, 2010 at 9:01 am
Tamino censored my response to his article, which included these two phase diagrams, showing that pressure approaches zero as temperature approaches zero.
Don’t feel like the Lone Ranger, Steve. I was censored, too, when I explained how adiabatic lapse rates work, which they mention, but apparently that’s just a cool science term they heard in passing. Not worth the trouble of typing a comment if Mr Foster is going to censor anyone more intelligent than he is (and I’ve looked it up).
I was amazed at the ad homs allowed over there, and the ‘Open Mind’ blog title is hilariously Orwell. What a pointless blog.
By the way, PV=nRT works in an oxygen tank or a spare tire, but it doesn’t mean much in an atmosphere bound only by gravity. P and T vary by altitude, and V is not measurable with no upper boundary.
I’ve put in a note for Virginia – if she should chance to read it
Well, Anthony, you predicted it: “now the howling begins.”
Sure enough, the poor lady got rewarded for her decency and civility with a load of venomous vile being hurled her way for daring to speak the unspeakable and mention WUWT in her column, and she commits a public act of contrition by agreeing that WUWT is a denialist site.
I wonder if she will still continue to sneak peeks at WUWT in the future, sort of like a guilty pleasure like sneaking a taste of chocolate when no one’s looking.
Yes Virginia, there is civil disagreement on the web and it’s on display right here. And when a line is crossed it gets snipped. And whether it’s Dr. Svalgaard, Dr. Curry, Dr. Meier, and others, they get treated with respect and consideration here, even if people here may disagree with things they may say or positions they may hold.
Can the same be said of the scienceblogs domain?
And as for all the nasty things said to her about WUWT — how’s that saying go about protesting too much?
Nullius in Verba
You are familiar with the mathematical idea of “approaching a limit?”
[b]Paul Birch[/b],
Given the thick clouds, Venus isn’t so much like a green house as it is a house-house with shingles on the roof. Very little light gets through the clouds, and as far as I know the surface illumination would meet the meteorological standards for any form of daylight here on Earth.
As for adiabatic heating, air is heated as a mass of air descends, so air lower down becomes hotter than it was up above. The air eventually rises and cools, but the cooling takes place as it rises, so this cooling doesn’t lower the air temperatures near the surface. It’s basically a constantly running heat engine with a compressor and an expansion orifice, like an air conditioner, heat pump, or refrigerator. The hot, high pressure side stays perpetually hotter than the cold side, establishing a fixed temperature difference between the two points. Then, somewhere, you connect a point on the circuit to the external environment which then sets the absolute temperatures everywhere else in the circuit.
In the case of Venus, the thick atmosphere and cloud cover keep the surface isolated from efficient, direct, radiated contact with the external environment, so the temperature is set by the upper atmosphere. As long as the adiabatic heat engine runs (strong vertical atmospheric circulation) the temperatures at low altitudes must be hotter than the high altitude temperature. It’s no coincidence that the temperature profile of Venus below the clouds almost exactly matches the adiabatic lapse rate, which would otherwise be rather inexplicable.
” Steve Goddard says:
July 31, 2010 at 11:48 am
The ideal gas law works just fine. When you get below the freezing point the number of gas molecules (N) drops off rapidly so the pressure also drops off rapidly.
PV=NRT”
The standard form is pV=NkT or pV=nRT (N number of molecules, k Boltzmann constant, n number of moles, R gas constant). Since there are 4 variables, one should indicate, which, if any, remain constant. “Freezing point” here is the one of water, I presume (273.15K = 0°C).
If PV=nRt works on Venus, how come it doesn’t work on earth?
The temperature extremes on earth are 183 K for the coldest and 330 K for the hottest.
Using the ideal gas law equation, that would mean if it was 1 atm in Libya, then it would be .55 atm in Vostok.
The actual highest recorded extremes of pressure are 1086 mb to 870 mb.
If the ideal gas law worked that way then there would be one heck of a wind blowing between the two.
Since there isn’t, that use of PV=nRt is nonsense.
” Paul Birch says:
July 31, 2010 at 1:05 pm
…adiabatic heating … only happens where air masses sink, and is inevitably offset by the corresponding cooling of the equal and opposite rising masses”
That is not true in the case of a moist wind going up one side of a mountain (wet-adi.), rain at the top, and dry wind coming down the other side (dry-adi.).
Bob,
How’s about big nuclear powered SUV’s…
Mike
OT: Hey, it appears that Mars’ southern polar region is colder than the northern one just like ours is. Why?
[EDIT: The south pole of Mars is at a pretty high altitude, while the north pole is significantly below average. Much as Antarctica is mostly above sea level and the Arctic is an ocean basin. – Mike]
Wasn’t there some allegation over in comments (not content) at the Register that Steve Goddard I were the same person? And that neither one of us actually exist? Or something like that.
From my own perspective, I think I disagree with the above premise. But, as an interested party, I cannot rely on my own experience. And it remains a fact that neither of us has ever been seen in the same room.
(If /when this issue is resolved, I’d appreciate it if someone let me know.)
Lambert was pwned…will not be back I predict.
Jeff,
Quicker than I am – both went to the same place…
On a serious note, I thought that science was the discipline that tried to figger things out…
This happens, then that happens, therefore this is a possible link between them.
When several possible links are proposed, evidence gathering begins.
CO2 is going up and so is the indicated temperature – link?
Cities have lots of asphault and concrete the indicated temp is going up – link?
software engineers are messing with the observed data – link?
ETC.
The point is that I think science is being done here and on several other internet sites – bringing together alternate or opposing views. To that end, Anthony, kudos…
More than my tax dollars are paying for…
Mike
Lambert is a nut – and his blog is occasionally used as a source by Connolley at wikipedia despite their personal friendship.
Ironically, Venus’ atmosphere is a lousy model for CAGW.
Here’s an example for a 1 layer model,
http://en.wikipedia.org/wiki/Idealized_greenhouse_model
and this gives an example for a n layer model
http://www.aps.org/units/fps/newsletters/200807/hafemeister.cfm
Plugging in the figures for Venus:
Veenus’ atmosphere has about 90 times the pressure of earth’s atmosphere, Venus’ gravity is about 10% weaker, so Venus’ atmosphere is about 100 times as dense as earth.
Venus temperature with clouds and wthout a greenhouse effect would be about
230 K. The actual temp is about 730 K, giving a multiplier of
730/230 = 3.17
Temperature is roughly proportional to the 4th root of the wattage flux, so
Venus’ atmosphere multiplies that surface flux by
(3.17)^4 =100.98, so Venus’ CO2 gives the equivalent of a 100 layer atmosphere,
Venus’ atmosphere is just about 100% CO2, and is 100 times as dense as earth’s.
Earth has about 0.04% CO2, so Venus has about 250,000 times as much CO2 as earth.
Venus’ 250,000 as much CO2 as earth gives Venus 100 atmospheres per this equation from my second link:
T0 = [(1 – a)so/4s]1/4 and Ts = (n + 1)1/4T0, (18)
Then earth’s CO2 would have the effect of
100/250,000 of an atmosphere multiplier effect or about
100/250,000 * 240 watts = 0.096 watts.
Assuming CO2 on earth has an effect of 30 to 40 watts, as indicated by theory,
saturation of bands plays a major part in keeping Venus from being a lot hotter in
simplistic theory than in practice.- amc
In the early stages of a new technology like the internet, there are apt to be many voices. Over time, readers come to discern the quality of the product, and brand names will be established. A few sites will emerge dominant as the new media. These sites will be the boutiques published by not by professional journalists (with WUWT an expection to the rule), but by (often retired) industry professionals. Whereas the New York Times will remain department store of journalism, with generalists covering many areas superficially, boutique websites will cover one area exhaustively. And because it’s so easy to switch from website to website, the boutiques will gut the department store new outlets over time.
Some of these new websites will cater to emotion, so to reason. Both can be viable models. For example, Keith Olbermann at MSNBC and Bill O’Reilly over at Fox both make a living catering to strong emotions, albeit on opposite sides of the political spectrum.
Other blogs will strive to be impartial, fair and informative–just plain, good news sources in the traditional sense. For these blogs, the key is to be comprehensive, open and relatively neutral in tone, with argument, to the extent possible, based on factual data. There may be an ideological predeliction, but data and analysis exist independent of–and take priority over–ideology. When people want to actually know what’s going on, rather than the official party line, they will seek out these sites.
To me, WUWT falls into this latter camp, and I think that’s why its readership continues to grow. It remains, I believe, the best climate website overall, with less stridency and the most content and educational value in the business.
George Turner says:
July 31, 2010 at 1:50 pm
“Given the thick clouds, Venus isn’t so much like a green house as it is a house-house with shingles on the roof. Very little light gets through the clouds, and as far as I know the surface illumination would meet the meteorological standards for any form of daylight here on Earth.”
Actually, ordinary houses are warmed by the greenhouse effect too. Sunlight gets through the windows, but it’s harder for the heat to escape. The difference is that in houses there is also thermal insulation that blocks conduction through the walls and roof too, which isn’t relevant in greehouses (or planetary atmospheres). “Very little light” is not no light; it is still sufficient to heat the Venusian surface. I’m not aware of any meteorological standard that surface illumination has to meet; it can get pretty black under a thundercloud.
“As for adiabatic heating, air is heated as a mass of air descends, so air lower down becomes hotter than it was up above. The air eventually rises and cools, but the cooling takes place as it rises, so this cooling doesn’t lower the air temperatures near the surface. It’s basically a constantly running heat engine with a compressor and an expansion orifice, like an air conditioner, heat pump, or refrigerator. The hot, high pressure side stays perpetually hotter than the cold side, establishing a fixed temperature difference between the two points. Then, somewhere, you connect a point on the circuit to the external environment which then sets the absolute temperatures everywhere else in the circuit.”
You’ve got cause and effect backwards. The circulation is cooling the surface, not warming it. The driver for the “heat engine” is not the pressure, it’s the sunlight reaching the surface (plus a bit of geothermal heat from the planet’s interior).
“As long as the adiabatic heat engine runs (strong vertical atmospheric circulation) the temperatures at low altitudes must be hotter than the high altitude temperature.”
Yes, but the circulation only runs because of the sunlight reaching the lower levels. If no sunlight penetrated the top of the clouds, the atmosphere would be isothermal, and stably stratified.
“It’s no coincidence that the temperature profile of Venus below the clouds almost exactly matches the adiabatic lapse rate, which would otherwise be rather inexplicable.”.
It’s not a coincidence, it’s a consequence of sufficient sunlight reaching the lower levels, or more accurately, a sufficient difference in the optical depths for incoming and outgoing radiation. Once there is sufficient net incoming radiation to raise the temperature to the adiabatic limit, convection commences, maintaining the adiabatic temperature profile. Lapse rates above the adiabatic rate are not sustainable, but lapse rates below that rate are not unusual. Dense atmospheres don’t always have an adiabatic temperature profile; only dense convective atmospheres. Dense atmospheres can also have both convective and radiative regions (this is an important consideration in stellar atmospheres, for example).
Alexej Buergin says:
July 31, 2010 at 2:06 pm
” Paul Birch says:
July 31, 2010 at 1:05 pm
…adiabatic heating … only happens where air masses sink, and is inevitably offset by the corresponding cooling of the equal and opposite rising masses”
“That is not true in the case of a moist wind going up one side of a mountain (wet-adi.), rain at the top, and dry wind coming down the other side (dry-adi.).”
Sure it is. In this case you just have to include the latent and sensible heats of the water vapour/precipitation. There can be no overall heating of the surface from this cause. Local heating, yes, but somewhere else is then being cooled by evaporation.
Kevin says:
July 31, 2010 at 2:12 pm
OT: Hey, it appears that Mars’ southern polar region is colder than the northern one just like ours is. Why?
IIRC it’s because Mars is closer to the Sun in the Northern summer. It’s not permanent. Every so often they’ll switch over as the perihelion and rotation axis precess.
Okay, let’s keep this on the NY Times or sharing a sentence with SciAm, I sure hope this doesn’t turn into a rehash of Venus, etc.
Oh dang. Too late. Oh – its “all about Pepsigate” – I’d rather rehash Venus, so I won’t complain. 🙂
I’ll drop Virginia a note after reading some of the other stuff and tell her why I like WUWT most days.
thegoodlocust says:
July 31, 2010 at 2:29 pm
Connolley at wikipedia
If Virginia Heffernan wanted to do an exposé on politics in science she could base it on William Connolley.
Poor Virginia! How did she not know that WUWT is part of a well-oiled machine on the wrong side of history? Is she really falling back on the old “I only read it for the pictures” excuse? I’m glad for her sake that she recanted now. WUWT is a “gateway blog”; next she would watch Glenn Beck with the sound off because he’s cute. Then maybe turn it up and find out his voice isn’t too bad either. Next thing you know, she can no longer get an outside table at Pinkerton’s and somehow her e-mail keeps dropping off the best distro lists. You have to nip these things in the bud.
Bob,
There are four degrees of freedom in the ideal gas law. You can’t solve for one without knowing or constraining the other three. You need to understand basic algebra.
CodeTech says, July 31, 2010 at 12:49 pm
The “peer reviewed” “science” in nutrition and medicine is in just as bad shape as in climate issues, if not worse.
You have no idea how true that statement is. After almost 20 years as a nutritionist, I don’t even bother reading papers any more. Most of them are total junk, paid for by the drug companies and the food companies to keep us fat and on medications for the rest of our lives.
“You are familiar with the mathematical idea of “approaching a limit?””
Yes. Yes, I am.
If you extend the ideal gas law beyond its domain of applicability, then as the temperature approaches zero, the volume tends to zero and the pressure remains a constant: mg/A. With zero volume, PV=nRT is satisfied. An ideal gas cannot condense or freeze.
In practice, once V falls below the volume of the atoms themselves, V can no longer be reduced any further and something has to give. What happens is that the gas ceases to be a gas, and the atmosphere loses both pressure and volume that way. It loses pressure because the atmosphere left now has less mass. Eventually, when there is no atmosphere left, the weight of atmosphere is zero and so is the atmospheric pressure. The pressure at the bottom of the solid crust of frozen Nitrogen/Oxygen is still 1 bar, of course.
It’s a minor point, that doesn’t detract from the excellence of the rest of the post. Pay no attention to Lambert.
Tim Lambert said: “Here’s the thing. Science works. Antibiotics work. And we know they work not because of any “bad-faith moral authority” by scientists but because they collected evidence and conducted experiments and drew conclusions that survived review by their peers.”
Apply this logic to history. “History tells us about the past. We know this, not because of belief in any “faith based history” from old books, but because historians have collected evidence and conducted investigations and drawn conclusions that survived review by their peers.
What historian would pretend that the collection of evidence and peer review was a sure-fire guarantee of correctness? We all know it is a “best guess” exercise, subject to massive revisions.
Yet rather too many science fanboys seem to think collection of evidence and surviving peer review alone is a guarantee of truth, despite well supported hypothesis in the past being overturned.
Alexej Buergin says:
July 31, 2010 at 10:04 am
Actually, the “ideal gas” is not a law, but one of the best examples of a model.
Another good model is the Einsteinian celestial mechanics of the solar system.
CodeTech says:
July 31, 2010 at 12:49 pm
“…..There are foods that I used to eat as a child in the 60s and 70s that are either no longer available or have morphed into a mere shadow of their former glory. Children today are NOT getting proper, required nutrition during their critical growing phase, since they are being robbed of fats and sugars by well meaning but ignorant people.
Are people healthier? No.
Am I obese? No. The opposite, in fact.
I smoke, I drink, I eat fatty and salty foods, I don’t get a lot of exercise, and yet at 46 I do exceptionally well at all the traditional indicators of health: blood pressure, heart rate, endurance, strength, etc. Stick that in your “peer reviewed” junk-science food war record book.”
Woot! Me, too! 2 packs/day and usually pick up a twelve pack on the way home from work. BP is still fine. HR is good. Respiration is WNL. lol My cholesterol is at the optimum.(I knew the egg bs was just that, never did slow down on the fried, over-easy) Weight is good, though I do seem to be getting a little soft in the middle. And I can still outwork most people half my age. I’ll be 46 in 2 months.
Yes, I too, lament the loss of taste in our food. It never ceases to amaze me how easily things are banned in this world because they may be unhealthy. As you pointed out, anything in excess could be unhealthy, but when they start mandating behavior, for our own well-being, they seem to think we’ll all be immortal if we just don’t ..smoke or drink or eat wrong foods, or eat real butter, or if we don’t swim without a lifeguard, or…ect.
In the words of Fredrick the Great, “Rascals! Do you want to live forever?” What the heck are you going to do if your body is healthy at 95? By then, for most, if dementia hasn’t already taken your mind, your senses will be dwindled to almost nothing so communication will be next to impossible. You’re still going to have to lay in some nursing home getting fed blended up food through a syringe and have the nurses aid once a shift check your diaper to see if your soiled or not, if they really care about the job. They can keep it. I’ll try to live, while others try to set longevity records for existence.
Kevin says:
July 31, 2010 at 2:12 pm
OT: Hey, it appears that Mars’ southern polar region is colder than the northern one just like ours is. Why?
It’s axis of rotation is tipped over more or less the same amount as earth’s axis.
It appears that a whole cottage industry has developed out of misquoting, misinterpreting and just plain lying about this obviously correct paragraph from the Venus article.
http://wattsupwiththat.com/2010/05/08/venus-envy/
Timmy banned me from his blog for refusing to apologize for using Google, no lie.
[snip]
REPLY: While I disagree with Mr. Lambert on most everything, I’ll also point out that I have been dealing with a person who has been an Internet stalker calling my office, showing up at my office unannounced, digging into my private life, trying to obtain my private business records, etc.
Therefore, I don’t condone you putting up his info, even if it is publicly available from a University, especially since you don’t use your own name in posts. I don’t condone bothering people at their place of work.
Please do not do this again. – Anthony
joshua corning
The amount of solar radiation reaching Jupiter is much lower than earth, so we would not expect to see the same temperature at the same atmospheric pressure. Nevertheless, temperatures at the bottom of the atmosphere are incredibly hot – because of the pressure.
I’m astonished that anyone who made it past junior high school science would even argue about this.
Poptech,
I want to thank you for putting together the long list of skeptical papers. It save me hours of digging for references and lets me see papers about things I never would of thought of.
Steve Goddard posts:
“There are four degrees of freedom in the ideal gas law. You can’t solve for one without knowing or constraining the other three. You need to understand basic algebra.”
Steve, actually three, but you are on the right track, I can’t do it for earth just the same as you can’t use it to explain the temperature of Venus.
Consider your explanation of the temperature of Venus debunked.
My apologizes as you could never find his office without [snip ]
REPLY: See above. Stop it. An apology is in order in comments if you wish to continue posting on WUWT, there’s no excuse for this sort of behavior. – Anthony
Well, I guess from her statements we know who Virginia Heffernan believed, choosing between her angry commenters or her lying eyes.
Diet and Nutrition have come up on this thread as well, just as deeply “religious” a subject as Climate Science has become. The abuse of science and statistics in the areas of diet and nutrition are so appalling as to render one speechless.
People ask my why I trust other scientists but not climate scientists – I laugh. Once you check one, you are shocked to discover that you need to check all.
I don’t know that the preference of mythology over solid scientific practice can be “fixed,” but I hope so.
James Sexton says:
July 31, 2010 at 4:34 pm
CodeTech says:
July 31, 2010 at 12:49 pm
“…..There are foods that I used to eat as a child in the 60s and 70s that are either no longer available or have morphed into a mere shadow of their former glory…
I agree with that too. I am in my sixties and can easily out work many male teenagers. I quit eating the crap in stores and restaurants and buy direct from the farmer if I can. The high fructose corn syrup dumped in everything these days is the real killer not the fats that are an absolute requirement for life. – yes life. Lack of fat KILLS, it was called rabbit starvation, my mother had it because of a diet from an idiot doctor placed her on.
I went back to eating a diet rich in fats and meat two years ago, my weight dropped and my blood pressure nose dived by 60 points! I feel twenty years younger.
I’d be really upset if I was compared to unscientific America magazine. It’s almost as bad as Bad (New) Scientist Magazine
What have the bottoms of their feet got to do with anything?
Karma is a fanciful construct for poets and storytellers, but has no basis in reality.
Gail, I am glad to hear it.
Timmy constructed a ‘troll dungeon’ to erase me and it worked, but after a full year of ad homs I was glad to see the back of the Deltoid larrikins.
bob
We will start with basic arithmetic.
1. Pressure
2. Temperature
3. Number of gas molecules
4. Volume
That is four degrees of freedom. Consider your elementary school education debunked.
Karma is simply the zero sum effect happening on all planes including the metaphysical. Will is the fifth and consolidating force. The Instanton (vritni in chetna) is ‘god/first cause’. Theosophy is the understanding of science and religion in the human context.
bob,
Quiz for you. It is over 20,000 degrees in the interior of Jupiter . This is because:
1. They get lots of sunshine 500 million miles away from the sun.
2. They are having a huge barbecue there.
3. The pressure is extremely high.
4. NASA is lying about the properties of Jupiter because they are being paid off by big oil.
Well, not exactly. The greenhouse-effect everyone worries about here on Earth assumes an atmosphere that is optically thin at visible wavelengths and optically thick at thermal wavelengths. Venus is optically thick in the visible for sure because we never see the surface. It must be optically thick at thermal wavelengths too.
Indeed Venus has a high albedo, my point was that an atmosphere, stirred vigorously by convection (it can only do so if there is some absorption at the surface) will approach an adiabatic temperature profile, and if sufficiently deep will reach a very high surface temperature.
OK, I agree, except the business about cooling as it rises is not pertinent. It cools (going up) and heats (going down) along the same temperature curve, unless there is latent heat from some precipitation. Transport by radiation is important too as you point out. Venus and Earth balance their “radiation books” at very different heights. That is why Venus can appear cool, when in fact its surface is literally hotter than hell; while Earth’s outgoing radiation depends to a great degree on surface temperature.
bob says:
July 31, 2010 at 2:05 pm
If PV=nRt works on Venus, how come it doesn’t work on earth?
The temperature extremes on earth are 183 K for the coldest and 330 K for the hottest.
Using the ideal gas law equation, that would mean if it was 1 atm in Libya, then it would be .55 atm in Vostok.
The actual highest recorded extremes of pressure are 1086 mb to 870 mb.
If the ideal gas law worked that way then there would be one heck of a wind blowing between the two.
Since there isn’t, that use of PV=nRt is nonsense.
BRAVO BOB!
Between you and Willis you’ve got it whipped, I think.
Venus’ heat source is volcanism.
I noticed that too. Mars has the most elliptical orbit of any of the planets (thus how Kepler was able to find his elliptical orbit “law” using the Mars data) except Mercury. I wonder if “summer” in the southern hemisphere on Mars also coincides with aphelion. No doubt the answer is on the internet someplace, but I feel no urgency to hunt right now.
stevengoddard says: July 31, 2010 at 5:06 pm
It appears that a whole cottage industry has developed out of misquoting, misinterpreting and just plain lying about this obviously correct paragraph from the Venus article. http://wattsupwiththat.com/2010/05/08/venus-envy/
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.
“Obviously correct,” huh? That was an interesting article we put together. Re-reading it I came across two quotes of yours, and one obviously correct one of mine.
stevengoddard says:
The ideal gas law works just fine, and gravity has nothing, nada, zippo to do with the accuracy of the equation.
stevengoddard says: . . .
As I have stated about 14 times now, the atmospheric pressure . . . is set by the weight of the atmosphere above it. P is fixed by the weight of the column of air above.
Mike McMillan says:
Weight requires gravity.
Anthony, are you going to ban Poptech?
Poptech has been suspended pending an apology here. His actions were just wrong and I’m sorry I didn’t see his shenanigans earlier.
Keith G says:
July 31, 2010 at 3:48 pm
“Poor Virginia! How did she not know that WUWT is part of a well-oiled machine on the […]“One regret: the Watts blog. Virtually everyone who emailed me pointed out that it’s as axe-grinding as anything out there. I linked […]”
CYA. Job security rules.
OK, in the strictest sense the pressure of the “atmosphere” would remain at 1 bar at sea level regardless of the temperature in order to hold its own mass up in the presence of Earth’s gravity. Nullius is right that a fully solidified “atmosphere” would still exert a pressure of 1bar at it’s base. When it has a vanishingly small volume and hence is no longer a gas common sense says that the ideal gas approximation no longer holds. I mean, is Lambert seriously asserting (csci – they like that word) that Venus and Earth would have an appreciable atmosphere in the absence of the sun? Even at 3K? I don’t consider the ocean, or ice, or the lithosphere to be part of the atmosphere regardless of the fact that they would all still have a finite vapor pressure at finite temperature. Perhaps Tim should check out how a cryopump works including the mongo one at JSC NASA used for testing Apollo equipment. To my knowledge it’s the largest vacuum chamber in the world. Or perhaps he should read a “Pail of Air” by Fritz Leiber. Fun story that gets the atmosphere part right, and he might just lighten up a bit.
However, another way of looking at it that Lambert would not enjoy is to pick a point somewhere in the atmosphere above sea level. Let’s say 5000ft. Now, what happens to this ideal gas atmosphere as we cool it by removing the sun? Well, the pressure at sea level stays constant, but the volume continues to shrink. In fact, the boundary between what we consider space and the atmosphere would collapse toward the surface. Staying at 5000ft I would see the pressure in the atmosphere drop as that boundary moved closer to me and eventually I would be outside the atmosphere. Wow, I’ve used ideal gas with gravity and without a phase change and I’ve seen a pressure drop with dropping temperatures. Pick any point above the thickness of a condensed atmosphere and you’ll see that effect. Imagine that. Oh, and don’t be pedantic and select a point already in deep space.
Alternatively, as Steve pointed out with his phase diagrams and Nullius mentioned, as parts of the atmosphere begin to condense out pV=nRT still holds but not only are V and T changing but n is changing(falling) as well. Less stuff in the atmosphere means less mass to suspend and lower pressure. But if you want to pick a point below the condensate, then it’s still 1 atmosphere of pressure. Again, it all depends on where you draw the line in your definition of “atmosphere.”
The bottom line is that aside from some nitpicking Steve’s post got most things right. A key point that these warmists apparently refuse to accept about Venus is that its atmospheric mass plays a role in its surface temps (and above) and not only through CO2 IR absorption.
p.s. Anthony, the lovely bit of your cousin, Mr. Douglas Watts, questioning if Jupiter was hotter than Venus was priceless.
Amino Acids in Meteorites says:
July 31, 2010 at 11:48 am
I have no training in science.
I could tell.
———-Reply:
Yes, but that silly science can sneak up on anybody–even the most unobservant. Expand your chest and the air rushes in; do the opposite and the air gets pushed out. Jump up and in short order you find yourself pulled back down, a phenomena that is repeatable ad nauseum. Skip down the sidewalk and each step takes you farther away; turn around and retrace your steps and you’re back again. No training required, Virginia, but a life of examples. These few mentioned include partial pressure, gravity, and friction.
Maybe Virginia will come to realize that people don’t need science “training” per se–science just IS. We can observe it all around us; we even see it in the mirror. All it takes for recognition is an open mind. Given that, your brain will do the rest.
Tsk Tsk says: July 31, 2010 at 8:09 pm . . .
p.s. Anthony, the lovely bit of your cousin, Mr. Douglas Watts, questioning if Jupiter was hotter than Venus was priceless.
That was one of the things I pointed out in my censored attempted post over on Taquino’s site. I even had the link to the NASA page that had the details. Sorry I gave him a page hit.
Jeff Alberts says:
July 31, 2010 at 6:36 pm (Edit)
CodeTech says:
July 31, 2010 at 12:49 pm
I do believe in Karma, and this is an awesome example of it…
Karma is a fanciful construct for poets and storytellers, but has no basis in reality.
================
Karma is a magical thinking label for the law of averages and regression to the mean.
Kevin says:
July 31, 2010 at 2:12 pm
OT: Hey, it appears that Mars’ southern polar region is colder than the northern one just like ours is. Why?
==============
Partly because, as prior posters have said, the south pole is tipped away from the sun at perhilion, but the south polar ice cap would not be nearly so stable if it were not significantly above the average elevation. Conversely, the Martian north pole is significantly below the average elevation, so the north pole always has higher atmospheric pressure and temperature than the south pole no matter what the season.
RockyRoad says:
July 31, 2010 at 9:39 pm
Yes, but that silly science can sneak up on anybody–even the most unobservant.
It happens to all of us. Einstein spent all of his time thinking about a problem until he knew he had it figured out good enough to go public. A good lesson to learn.
“If A equals success, then the formula is A = X + Y + Z. X is work. Y is play. Z is keep your mouth shut.”
— Albert Einstein
Venus is either about gravity and pressure, or it’s that force that pulls dogs gone bad.
“Magnetism is one of the Six Fundamental Forces of the Universe, with the other five being Gravity, Duct Tape, Whining, Remote Control, and The Force That Pulls Dogs Toward The Groins Of Strangers.”
~Dave Barry
Exactly.
Tsk Tsk says:
July 31, 2010 at 8:09 pm
Wow, I’ve used ideal gas with gravity
“Scientists tell us that the fastest animal on earth, with a top speed of 120 feet per second, is a cow that has been dropped out of a helicopter.”
But what will happen to the cow on Venus?
I’m fascinated with the differing conclusions about adiabatic pressure/ temperature arguments by people well versed in math and physics, which I am not.
To stir the pot a little more I throw in the following:-
From NASA http://voyager.jpl.nasa.gov/science/neptune_neptune.html
“Voyager also measured heat radiated by Neptune’s atmosphere. The atmosphere above the clouds is hotter near the equator, cooler in the mid-latitudes and warm again at the south pole. Temperatures in the stratosphere were measured to be 750 kelvins (900 degrees F), while at the 100 millibar pressure level, they were measured to be 55 K (-360 degrees F). Heat appears to be caused, at least in part, by convection in the atmosphere that results in compressional heating: Gases rise in the mid-latitudes where they cool, then drift toward the equator and the pole, where they sink and are warmed.”
So it appears that as long as there is a heat engine working, pressure causes warming.
Not that I believe everything on a NASA website, especially since the Miscolski affair!
Don’t ignore a Tim Lambert, as he’s one of the world’s most influential climate scientists. He’s so respected Realclimate sometimes references his dissembling and dishonesty.
When liquids or solids (like snow or rain) condense out of the atmosphere, they no longer are part of the atmosphere. They no longer contribute to atmospheric pressure.
Rain which falls in the ocean contributes to ocean pressure, not atmospheric pressure.
Snow which falls on a glacier contributes to the weight of the ice, it does not contribute to atmospheric pressure.
Only a gas can contribute to atmospheric pressure.
Mike McMillan
You are making a total straw man argument.
I said that gravity does not affect the “accuracy of the equation.” The ideal gas law does not make any attempt to explain what controls any of the variables, it simply defines their relationships. Sometimes pressure is caused by gravity. Sometimes it is caused by other things.
That is in no way contradictory or even related to what you are saying. Your attempt to set them up as contradictory is nonsensical.
Yes Mike,
This paragraph is obviously correct. If you don’t understand it., I can’t help you.
@ justin ert, I believe that the greatest dangers facing the world are “Truth relativism” and “Secularism”, both of which are very liberal battle cries.
http://en.wikipedia.org/wiki/Messinian_salinity_crisis#Climate
Try throwing this in the mix. 😀
bob says:
July 31, 2010 at 10:14 am
…what I want to know is where did all the water on Venus go, why is there an excess of deuterium in the atmosphere, and where did all the CO2 come from?
Those are interesting questions, although perhaps deserving of a thread all of their own. The presence of water on Earth and its absence on Venus IS one of the major differences.
If the oceans did not exist on Earth, all the CO2 dissolved in them would instead be in the atmosphere. Plus, the processes that led to the creation of all the Carbonate rocks (chalk, limestone etc) would not have operated, so that all the CO2 sequestered in those rocks would also be in the atmosphere. In other words, Earth’s atmosphere would contain a very substantial proportion of CO2, much higher than today.
So, the crucial difference between Venus and Earth revolves around the presence of water here on Earth and its lack on Venus. I’ve seen various debates about the reason for this difference, but I am not sure that there is one convincing explanation.
Always enjoy reading posts like this. Or the ones discussing the Arctic Death Cycle. Always something to learn and nice to see opposing points of view (mostly) respectfully discussed. Despite what that silly lady from the NYT was told.
Just find it hard to understand why the temperature / pressure on Jupiter or some melting ice floes in the Arctic present convincing reasons why I’m warming Earth if I forget to switch off the TV standby light. Or why we need to build tens of thousands of wind turbines which basically don’t work and shut down coal and gas plants that do work.
Sorry if I’m being abstruse.
” bob says:
July 31, 2010 at 2:05 pm
If PV=nRt works on Venus, how come it doesn’t work on earth?
The temperature extremes on earth are 183 K for the coldest and 330 K for the hottest.
Using the ideal gas law equation, that would mean if it was 1 atm in Libya, then it would be .55 atm in Vostok.”
Your calculation implies that Volume V and number of moles n are constant; so you are talking about a gas that is enclosed in a bottle. If you transport that bottle from Libya to Vostock, let it cool down (it is not insulated), then the pressure will drop from 1013 hPa to 562 hPa just as you say.
stevengoddard says:
July 31, 2010 at 5:06 pm
It appears that a whole cottage industry has developed out of misquoting, misinterpreting and just plain lying about this obviously correct paragraph from the Venus article.
“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.”
It’s a nearly correct paragraph. What it should say is “if there were no Sun (or other external or internal energy source) …”.
This is important when it comes to Jupiter. You said,
“It is over 20,000 degrees in the interior of Jupiter . This is because:
1. They get lots of sunshine 500 million miles away from the sun.
2. They are having a huge barbecue there.
3. The pressure is extremely high.”
You probably thought you were being humorous, but the correct answer is 2. The interior of Jupiter is heated primarily by processes such as radioactive decay, latent heat release due to phase changes, gravitational contraction (and, of course, the left-over gravitational energy from the original condensation of the planet). The lower atmosphere of Jupiter is also heated by the Sun; even though the optical depth is high, more sunlight still gets through than can escape again by radiation alone. The high pressure (or, more precisely, the high density) is a major factor in the operation of these mechanisms, but of itself it does not and cannot cause heating. It is passive; high temperatures need an active energy source. Like a barbeque.
“1. Pressure 2. Temperature 3. Number of gas molecules 4. Volume
That is four degrees of freedom. ”
PV=nRT has four variables, one constant, and therefore just three degrees of freedom.
stevengoddard says:
July 31, 2010 at 5:06 pm
It appears that a whole cottage industry has developed out of misquoting, misinterpreting and just plain lying about this obviously correct paragraph from the Venus article.
“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.”
It’s a nearly correct paragraph. What it should say is “if there were no Sun (or other external or internal energy source) …”.
This is important when it comes to Jupiter. You said,
“It is over 20,000 degrees in the interior of Jupiter . This is because:
1. They get lots of sunshine 500 million miles away from the sun.
2. They are having a huge barbecue there.
3. The pressure is extremely high.”
You probably thought you were being humorous, but the correct answer is 2. The interior of Jupiter is heated primarily by processes such as radioactive decay, latent heat release due to phase changes, gravitational contraction (and, of course, the left-over gravitational energy from the original condensation of the planet). The lower atmosphere of Jupiter is also heated by the Sun; even though the optical depth is high, more sunlight still gets through than can escape again by radiation alone. The high pressure (or, more precisely, the high density) is a major factor in the operation of these mechanisms, but of itself it does not and cannot cause heating. It is passive; high temperatures need an active energy source. Like a barbeque.
“1. Pressure 2. Temperature 3. Number of gas molecules 4. Volume
That is four degrees of freedom. ”
PV=nRT has four variables, one constant, and therefore just three degrees of freedom.
Kevin Kilty says:
July 31, 2010 at 7:19 pm
“Well, not exactly. The greenhouse-effect everyone worries about here on Earth assumes an atmosphere that is optically thin at visible wavelengths and optically thick at thermal wavelengths. Venus is optically thick in the visible for sure because we never see the surface. It must be optically thick at thermal wavelengths too. ”
The greenhouse effect arises from a difference in the optical depths for incoming and outgoing radiation. Anywhere there’s a difference in the two, you get greenhouse warming. The bigger the difference the bigger the warming. On Earth the difference is small (except under heavy cloud, the atmosphere is not optically thick either for sunlight or for thermal radiation). On Venus the difference is large. So Earth has a weak greenhouse effect and Venus a very strong one.
“… the business about cooling as it rises is not pertinent. It cools (going up) and heats (going down) along the same temperature curve, unless there is latent heat from some precipitation. ”
Quite. Or unless there is net warming from sunlight or a warmer surface, or net cooling from radiation.That’s why neither the adiabatic warming of sinking masses, nor the cooling of the rising masses, per se, are really pertinent. They’re not what warms the surface and lower atmosphere – it’s the incoming radiation that does that – the convection currents are what (along with some outgoing radiation) actually cools them.
Temperatures in Jupiter’s atmosphere are extremely hot, in spite of the very low amount of solar radiation. This is a function of atmospheric pressure, just like on every other planet.
http://juno.wisc.edu/Images/using/Instruments/MWR/MWR_Weighting_Function.jpg
So Tim Lambert misunderstands physical law and claims that everyone else is wrong. What’s new about that?
Ref – Jim Barker says:
July 31, 2010 at 9:27 am
“Its seems as the political thought content increases, the critical thought content approaches zero.”
_________________________
Non! Non! As the blood boils, ze brain she fries, ze thoughts approaches zero, and humans becomes like mad dogs and irishmen.
Top of the mornin’ to ye!
stevengoddard says:
August 1, 2010 at 7:08 am
“Temperatures in Jupiter’s atmosphere are extremely hot, in spite of the very low amount of solar radiation. This is a function of atmospheric pressure, just like on every other planet.”
It is a function of differences in optical depth for incoming and outgoing radiation. It has very little to do with pressure as such (pressure alone cannot heat an atmosphere) except that the more stuff you have, and the denser it is, the more easily you can block radiation, whether through clouds or aerosols or absorbing gases – or through clouds of locusts or flying elephants! With a suitable choice of materials – such as black aerosols and dark-coloured vapours like iodine, preferably in a mainly monatomic gas like neon, or high-level optically thick clouds that dissipate during the day and reform rapidly at night – I could design a planetary atmosphere that was hot at the base despite being quite thin. Where the pressure does come in is that the ratio of pressures relative to that at the radiating top of the atmosphere determines the convection-limited maximum temperature ratio (for given ratio of specific heats, which is itself a function of the atmospheric composition and density). Note that it is the ratios that matter here, not the absolute values. Gravity is also relevant, insofar as, for a given pressure or density, the depth of the atmosphere is proportionally greater the weaker the gravity.
Paul Birch
I made it abundantly clear that the Sun is the energy source. It is adiabatic heating/cooling as the atmosphere convects, which produces the temperature/pressure gradient. It has little or nothing to do with optics. Venus is very cloudy, but you see similar temperatures at 1 bar on Venus as you do on earth.
Paul Birch,
Why is it typically 100 degrees F cooler on the top of Mount Everest than it is at the same latitude in Saudi Arabia?
It has nothing to do with optics. They both receive the same amount of sunshine It is the pressure difference in the atmosphere.
Paul Birch,
“It is a function of differences in optical depth for incoming and outgoing radiation.”
The troposphere varies in temperature from -54 C at the top to +14 C at the bottom, in a straight line. (International Standard Atmosphere.) I suggest that the fact that it is a single straight line suggests that the reason the top of the atmosphere is so cold is the same as the reason the bottom of the atmosphere is warm. The same basic mechanism is behind both.
Perhaps you could comment on how optical depth differences explain the top of the atmosphere being so cold – more than 30 C colder than the effective radiative temperature?
Likewise, is the reason that mountain tops are so cold that they are not at the same optical depth? If air passes over a mountain range and down onto the plains on either side, how does the change in optical depth alter its temperature so quickly?
Thanks.
For what it was worth, I just sent a nice email to Virginia Heffernan. I pointed out how she didn’t notice the “denialism” until she was told it was there, and that perhaps she should give it another read.
I thought hers was a very sad story: she read the blog, correctly picked up on its scientific integrity and welcome for all points of view, and then allowed herself to be “corrected” regarding it. Perhaps she’ll come back again, guiltily looking over her shoulder. I think more of us should encourage her.
stevengoddard says:
I said that gravity does not affect the “accuracy of the equation.” The ideal gas law does not make any attempt to explain what controls any of the variables, it simply defines their relationships. Sometimes pressure is caused by gravity. Sometimes it is caused by other things.
stevengoddard says:
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.
Of course, near absolute zero we aren’t going to have an atmosphere, so yes pressure is zero.
My point was that PV=nRT doesn’t work in the presence of gravity. It’s a good approximation in an enclosed tank of gas, but not at all for a planetary atmosphere.
If you actually plug some real numbers into the equation, STP and 230.21 moles of air for n, you get a volume of 314680 cubic inches of air sitting atop 1 square inch of Houston. That tops the atmosphere out at 26,223 ft, half a mile below the summit of Mt Everest.
Steven’s right about Jupiter and about the temperature lapse rate. An atmosphere will sort itself out so that temperature increases with depth, and will attempt to correct any anomalies.
Anyone can check a college level general chemistry textbook and look up the Ideal Gas Law.
They will find there are several restrictions on the use of the Ideal Gas Law.
It is applicable for high temperatures (greater than 300K) and low pressures (less than 1 atm).
It also assumes elastic collisions between molecules.
Steve Goddard also posts
“When liquids or solids (like snow or rain) condense out of the atmosphere, they no longer are part of the atmosphere. They no longer contribute to atmospheric pressure.
Rain which falls in the ocean contributes to ocean pressure, not atmospheric pressure.
Snow which falls on a glacier contributes to the weight of the ice, it does not contribute to atmospheric pressure.
Only a gas can contribute to atmospheric pressure.”
Liquids and solids also have vapor pressures determined by their temperature so they do indeed contribute to the atmospheric pressure.
A gas will behave approximately ideally if its temperature is above the critical temperature and/or pressure is below critical pressure. The critical values vary from one gas to another. Carbon Dioxide, for example, has critical T of 304K and critical P of 7.4 MPa (about 70 atmospheres). The permanent gasses of Earth’s atmosphere all have low critical T (below 155K) and critical P no lower than 3.4MPa.
“….next she would watch Glenn Beck”
Equating WUWT to Glenn Beck in any ways should actually be seen as a smear.
I think we are arguing past one another here, and have gotten away from the point of my post. The pertinent quotation from the head of this thread is…
Indeed, I only meant to point out that Venus’ surface temperature is partially related to the mass, hence surface pressure, of the atmosphere. Venus reaches a temperature of 230K at a height of 60+ km. The temperature profile from here to the surface looks very linear, which implies to me that the profile results from vertical convection. If Earth’s had a troposphere 60+ km thick, its surface temperature would be quite high as well (except for the question about how much heat would thermal radiation be able to transport away from its surface). Venus can transport energy away from the surface only by convection as the optical depth for thermal radiation is very large. The optical depth for visible is also large, the proof being we can see no surface features, and as you point out only about 10 watts per square meter of visible energy reaches the surface. These two statements are equivalent. Jupiter and Saturn have a surprisingly similar situation. Thus, Lambert’s mocking is misplaced.
Tsk Tsk says July 31 2010 8:09pm
Really , you shouldn’t believe everything “scientists say”,
68k – 10 sec @ 56k
videosift.com/video/Peregrine-falcon-recorded-going-183.
😉
” bob says:
August 1, 2010 at 3:53 pm
the Ideal Gas Law…
… also assumes elastic collisions between molecules.”
No, it assumes NO collision between molecules. If the molecules collide, momentum gets displaced faster, and you have to use the Van der Waals equation.
(If you hit one billard ball, momentum mv moves with the speed v. If you have 10 billard balls touching each other, and hit the first one, momentum jumps almost instantly to the last ball and its collision with the next wall occurs earlier).
stevengoddard says:
August 1, 2010 at 8:19 am
Paul Birch
“I made it abundantly clear that the Sun is the energy source. ”
For Venus, yes. Not in the case of Jupiter. The reason for the (assumed) high temperatures in the jovian interior is the heat being generated down there (as you say in the first comment), and the high optical depth that prevents its being simply radiated away; the solar warming is important only higher up.
“It is adiabatic heating/cooling as the atmosphere convects, which produces the temperature/pressure gradient.”
It is the convective cooling that limits the temperature gradient. It does not produce it. It really is important to grasp this distinction. Not every atmosphere is convective at depth, and every (unconfined) atmosphere has an outer non-convective layer.
“It has little or nothing to do with optics.”
It has everything to do with the optical depths (and reflectivities). That’s basic physics. I’ve explained how it works; do you not understand the explanation? A fully transparent atmosphere under uniform insolation would be isothermal. Vertical convection arises when heat is being radiated from the upper atmosphere faster than radiation from below can replenish it. Radiation is a question of optical depths.
“Venus is very cloudy, but you see similar temperatures at 1 bar on Venus as you do on earth.”
Actually, they are quite a bit lower. That they are even that close is mostly coincidence.
“If there were no Sun (or other external energy source) atmospheric temperature would approach absolute zero. ”
Why you insist on repeating this is beyond me. Are you so unwilling ever to accept that you’ve slipped up, or been imprecise (which everyone does, it’s no big deal)? The sentence still needs to read “or other external or internal energy source”. Surely you can see that with an internal energy source the atmosphere would find a (lower) equilibrium temperature that could be a long way above absolute zero. Even on Earth, geothermal heat would keep the temperature to ~30K, leaving a thin neon atmosphere.
“Why is it typically 100 degrees F cooler on the top of Mount Everest than it is at the same latitude in Saudi Arabia?
It has nothing to do with optics. They both receive the same amount of sunshine It is the pressure difference in the atmosphere.”
First, if we avoid cherry-picking hot to cold, the average temperature difference is more like 40C. Second Everest is much cloudier than Saudi Arabia, so it receives much less sunshine. Third, Everest has a much higher surface albedo than Saudi Arabia. Fourth, it’s the pressure ratio that affects the adiabatic temperature profile, not the pressure difference. Fifth, optical depth differences are a function of how much atmosphere you have above you; other things being equal, optical depths (and greenhouse warming) will be less the higher the altitude. This is obviously related to the local atmospheric pressure, but pressure is not the fundamental variable; you can’t simply switch between different planets to the same pressure level.
Again, if we imagine a fully transparent atmosphere under uniform insolation, the atmosphere would be everywhere isothermal and surface temperature would be independent of the surface altitude.
If we now imagine a fully transparent atmosphere under non-uniform insolation, horizontal convection will occur between the hotter and cooler regions. Atmospheric pressure will be slightly higher in the cool region, causing air to flow towards the lower pressure warm region. The air then warms in contact with the ground and rises, cooling adiabatically until it reaches the height at which its temperature is at the average for the two regions. There it flows back down the slope under gravity towards the cool region. Above that convection zone the atmosphere will remain isothermal, at the average temperature, and will be slightly thicker over the cool region; the bottom boundary slants down from the warm to the cool regions, creating the slope that lets the convected air flow back to the higher pressure cool region.
A fully convective atmosphere will only arise when there are large optical depth differences that obviate purely radiative equilibrium, or large insolation differences across the planet. Or both. Earth sometimes has both. Not always. Earth’s atmosphere is not fully convective, and there are often regions where the temperature falls off less rapidly with altitude than the abiabatic lapse rate (there are even actual temperature inversions). This makes Earth’s weather very complicated and highly variable (water vapour makes things even worse). Where the atmosphere is strongly convective, the lapse rate becomes predictable, and local temperatures will follow the local altitude (or pressure) quite well. That is why we can see a well-defined correlation of temperature versus altitude. Nevertheless, this is a local not global effect. If we took away half the atmosphere, leaving 500mbar, temperatures would not drop to the level seen on Everest at the 500mbar height today. They would barely drop at all, perhaps a few degrees. They might even rise, due to subtleties like cloud formation.
Nullius in Verba: I think the above probably answers most of your points. Remember that in reality the atmosphere doesn’t radiate from just a single level, because there is no discrete height at which the atmosphere is optically thick (though clouds can come close to this). The “effective temperature” is a composite; some of the energy radiates from a higher temperature, some from a lower temperature.
Alexej Buergin says:
August 2, 2010 at 1:53 am
“bob says:
August 1, 2010 at 3:53 pm
“the Ideal Gas Law…also assumes elastic collisions between molecules.”
No, it assumes NO collision between molecules. If the molecules collide, momentum gets displaced faster, and you have to use the Van der Waals equation.”
Actually it assumes either or both. The crucial assumption is that the molecules are point masses (have zero volume), so although collisions between them are elastic, the rate of collisions is zero!
“Of course, we can’t have that, now the howling begins.”
I’ve noticed a bunch of new names posting comments since this article was posted.
Thanx, NY Times. As you continue to swirl down the bowl, you can take a little credit for contributing to WUWT’s increasing traffic.
Paul Birch says:
August 2, 2010 at 4:48 am
stevengoddard says:
August 1, 2010 at 8:19 am
Paul Birch
“I made it abundantly clear that the Sun is the energy source. ”
“Venus is very cloudy, but you see similar temperatures at 1 bar on Venus as you do on earth.”
Actually, they are quite a bit lower. That they are even that close is mostly coincidence.
—
Hmmm, nope. Googling quickly gave me this. Now that may be wrong, but 1bar of pressure occurs at 49.5km and just eyeballing the temp vs. altitude plot I get something closer to 350k. That’s a tad toastier than it is on Earth and I would guess correlates well with the higher insolation of Venus.
Or were you being imprecise and referring to Earth being cooler?
—
“If there were no Sun (or other external energy source) atmospheric temperature would approach absolute zero. ”
Why you insist on repeating this is beyond me. Are you so unwilling ever to accept that you’ve slipped up, or been imprecise (which everyone does, it’s no big deal)?
—
Just a guess, but probably for the same reason you’re being so pedantic about it. Remember, it’s no big deal.
Paul Birch,
Thank you very much for your excellent and informative (and patient!) contributions, I’m sure Steve Goddard can improve the quality of his essays thanks to your corrections.
” Paul Birch says:
August 2, 2010 at 6:47 am
The crucial assumption is that the molecules are point masses (have zero volume), so although collisions between them are elastic, the rate of collisions is zero!”
So you are saying:
There are no collisions
but if there were collisions
they would be elastic
How about that.
(Yes, otherwise it would not be the same molecule anymore, but something with more mass).
The point is: In the ideal gas, there are no collisions between molecules, but elastic collisions of the molecules with the walls.
Tsk Tsk says:
August 2, 2010 at 7:10 pm
stevengoddard: “Venus is very cloudy, but you see similar temperatures at 1 bar on Venus as you do on earth.”
Paul Birch: “Actually, they are quite a bit lower. That they are even that close is mostly coincidence.”
—
Hmmm, nope. Googling quickly gave me this. Now that may be wrong, but 1bar of pressure occurs at 49.5km and just eyeballing the temp vs. altitude plot I get something closer to 350k. That’s a tad toastier than it is on Earth and I would guess correlates well with the higher insolation of Venus. Or were you being imprecise and referring to Earth being cooler?
_______________________________________________
I’d say ~340K from those graphs, but, yes, that’s warmer than Earth, not cooler. My mistake. It’s actually a bit hotter than I thought (I was using pre-1990 data from my 1991 Venus terraforming paper). My point that the similarity is coincidental still holds, and indeed is strengthened. Thank you.
“Just a guess, but probably for the same reason you’re being so pedantic about it. Remember, it’s no big deal.”
No, but the fact that planetary surface temperatures are increased not by the mere pressure of the atmosphere but as a consequence of the different optical depths and reflectivities for incoming and outgoing radiation is crucial to understanding climate, whether on Earth or elsewhere.
Alexej Buergin says:
August 3, 2010 at 12:31 am
“…The point is: In the ideal gas, there are no collisions between molecules, but elastic collisions of the molecules with the walls.”
Strictly speaking, you’re right, of course. However, where the elastic collisions between molecules do come in is in calculations of mean free path, diffusion and heat flow. We still use the simplified ideal gas, obeying the ideal gas law, but assume billiard ball molecules colliding elastically. Because the volume of the billiard balls is a small fraction of the total volume, for gases at or below a few atmospheres (ie gases much less dense than the liquid or solid phases), the ideal gas assumption is still a good approximation.
” Paul Birch says:
August 3, 2010 at 4:45 am
Strictly speaking …”
“Strictly” is the only way, since this is physics, not climatology.
And now we agree, as you can see from my posting of July 31 at 9:48am
Anthony, my apologies as I did not see your request before my second post. I had no intention of posting something you did not approve of. I completely understand and will refrain from posting all online freely available personal information about Mr. Lambert here again.