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
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 @ur momisugly 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.