A look at diminishing atmospheric pressure
Guest post by Andi Cockroft
In an unrelated article of mine on Isostacy and Mean Sea Level posted here, I mentioned in passing a thesis paper by Theresa Cole (here) and here: ColeTheresaN2011MSc – which included this graph depicting an observed fall in global annual mean atmospheric pressure since 1916 (from NOAA I believe)
A recent exchange with Theresa, has caused me to revisit this apparent anomaly, and wonder where this is all heading – and indeed how long this has been going on !
But why the heading – So Dinosaurs Could Fly ?
Well, seems that engineers are of the opinion that the pterosaurs were just too heavy to get off the ground given today’s environment, and they must have been helped by far denser air.
Denser air of course means a higher pressure – I have seen estimates ranging from about 3.5 to 8 times that of today. Let’s pick a mid-point of say 5 for the purpose of this post. (I trust these are not the same engineers who state categorically that a Bumble-Bee is incapable of flight)
So from 100Mya to today, how has air pressure gone from a possible 5000 mbar to 1013 mbar of today? And why is it still (possibly) continuing to fall?
Questions that spring to mind are:-
· Is our atmosphere being sucked out in to space?
· Is the composition of the atmosphere changing and so getting lighter?
· Change in water vapour?
· Increasing CO2
· Burning hydrocarbons + O2 -> CO & CO2
· Volcanic eruptions
· Release/Uptake of gases from/to the ocean
· O3 -> O2
· Is an increase in temperature causing a somehow related increase in pressure?
For those who might not remember, I remind readers I do not have strong scientific qualifications in meteorology, hydrology chemistry etc., just an enquiring mind – so feel free to disagree with my arguments here.
In researching this post, I came across many conundrums. Many contradictions or seemingly incongruent theories. But hey, let’s look at what is out there starting with young Earth and work forwards to see what we shall reveal.
I also found myself using those well used weasel words such as could, may, might, suppose etc. Sorry, but given the nature of the discussion – this is just what it is a discussion of some possibilities – not proven fact!
So, just looking at the graph in figure 1 of the past 90 years:- Temperature may have localised effects, but in general, global mean atmospheric pressure at sea level is directly proportional to the mass of the entire atmosphere – the current accepted mean value is around 1013.25 Mbar. So any warming observed over the past 90 or so years should be ruled out as causation – warm or cold the air weighs the same (within reason)
A drop of 1 Mbar may seem trivial over 90 years, but at that rate mother Earth may run out of atmosphere altogether in just 100,000 years !!
Going back 100 million years, for a pressure equivalent to 5000 Mbar, there would have to be either (a) a lot more air, or (b) different composition – or a combination of each.
And of course the raging question – how has a 5000 Mbar atmosphere reduced to todays 1013.25 Mbar?
The Levenspiel et al 2000 paper is well worth a read, and has been cited indirectly here as part of 450 Peer-Reviewed Papers Supporting Skepticism of AGW caused Global Warming here, and referred to at WUWT here.
What was the air pressure for the 97% of Earth’s life before the age of dinosaurs? Levenspiel et alhave three possible alternatives, as shown in Figure 3.
- The pressure could have been at 1 bar throughout Earth’s earlier life, risen to 4–5 bar ~100 Mya (just at the time when the giant fliers needed it), and then returned to 1 bar (curve A).
- The pressure could have been ~4–5 bar from Earth’s beginning, 4600 Mya; and ~65 Mya, it could have begun to come down to today’s 1 bar (curve B).
- The atmosphere could have started at higher pressure and then decreased continuously through Earth’s life to ~4–5 bar ~100 Mya and down to 1 bar today (curve C).
The third alternative seems to be the most reasonable, so let us pursue it. We will also look into the composition of Earth’s atmosphere, but we will first discuss Earth’s surface and see how it affects the atmosphere.
From http://www.engineeringtoolbox.com, the specific gravity of some common gases can be found in the table below:
| Gas | Specific Gravity |
| Acetylene (ethyne) – C2H2 | 0.90 |
| Air1) | 1.000 |
| Alcohol vapour | 1.601 |
| Ammonia – NH3 | 0.59 |
| Argon – Ar | 1.38 |
| Arsine | 2.69 |
| Benzene – C6H6 | 2.6961 |
| Blast Furnace gas | 1.02 |
| Butadiene – C4H6 | 1.87 |
| Butane – C4H10 | 2.0061 |
| 1-Butene (Butylene)- C4H8 | 1.94 |
| Isobutene – C4H8 | 1.94 |
| Carbon dioxide – CO2 | 1.5189 |
| Carbon monoxide – CO | 0.9667 |
| Carbureted Water Gas | 0.63 |
| Chlorine – Cl2 | 2.486 |
| Coke Oven Gas | 0.44 |
| Cyclobutane | 1.938 |
| Cyclopentane | 2.422 |
| Cyclopropane | 1.451 |
| Decane | 4.915 |
| Deutrium – D2 | 0.070 |
| Digestive Gas (Sewage or Biogas) | 0.8 |
| Ethane – C2H6 | 1.0378 |
| Ether vapour | 2.586 |
| Ethyl Chloride – C2H5Cl | 2.23 |
| Ethylene (Ethene) – C2H4 | 0.9683 |
| Fluorine | 1.31 |
| Helium – He | 0.138 |
| Heptanes | 3.459 |
| Hexane | 2.973 |
| Hydrogen | 0.0696 |
| Hydrogen chloride – HCl | 1.268 |
| Hydrogen sulfide – H2S | 1.1763 |
| Hydrofluoric acid | 2.370 |
| Hydrochloric acid | 1.261 |
| Illuminating gas | 0.4 |
| Isobutane | 2.01 |
| Isopentane | 2.48 |
| Krypton | 2.89 |
| Marsh gas | 0.555 |
| Mercury vapour | 6.940 |
| Methane – CH4 | 0.5537 |
| Methyl Chloride | 1.74 |
| Natural Gas (typical) | 0.60 – 0.70 |
| Neon | 0.697 |
| Nitric oxide – NO | 1.037 |
| Nitrogen – N2 (pure) | 0.9669 |
| Nitrogen – N2 (atmospheric) | 0.9723 |
| Nitrous oxide – N2O | 1.530 |
| Nonane | 4.428 |
| Octane | 3.944 |
| Oxygen – O2 | 1.1044 |
| Ozone | 1.660 |
| Pentane | 2.487 |
| Phosgene | 1.39 |
| Propane – C3H8 | 1.5219 |
| Propene (Propylene) – C3H6 | 1.4523 |
| R-11 | 4.742 |
| R-12 | 4.174 |
| R-22 | 2.985 |
| R-114 | 5.9 |
| R-123 | 5.279 |
| R-134a | 3.522 |
| Sasol | 0.42 |
| Silane | 1.11 |
| Sulfur Dioxide – SO2 | 2.264 |
| Toluene-Methylbenzene | 3.1082 |
| Water gas (bituminous) | 0.71 |
| Water vapor | 0.6218 |
| Xenon | 4.53 |
1) NTP – Normal Temperature and Pressure – is defined as air at 20oC (293.15 K, 68oF) and 1 atm ( 101.325 kN/m2, 101.325 kPa, 14.7 psia, 0 psig, 30 in Hg, 760 torr)
Since specific gravity is the ratio between the density (mass per unit volume) of the actual gas and the density of air, specific gravity has no dimension. The density of air at NTP is 1.205 kg/m3
To change the “mass” of the atmosphere to any meaningful way would require say a 75% mercury vapour composition – something not altogether conducive to life as we know it. The alternative is of course just a lot more atmosphere.
Turning our attention for a moment to Earth’s twin, Venus, formed in probably very similar environs, yet Venus retains an atmosphere composed of CO2 and Nitrogen, with a pressure equivalent of around 90 Bar. Venus is closer to the Sun, so receives greater energy, but that cannot in itself account for the very significant differences in today’s environments.
Levenspiel postulates that the creation of Earth’s companion Moon stripped off much of Earth’s mantle, leaving it a rather fluid lithosphere compared to Venus. It is this fluid lithosphere that has allowed continental drift to rearrange and directly affect the planet’s atmosphere. Couple that with a slightly cooler Earth (less sunlight), allowing liquid water to form, and the basis for removal of CO2 is formed.
If say 4 Bya, Earth did have an atmosphere with a 90% CO2 concentration, with a high atmospheric pressure, Levenspiel proposes that simple dissolution in water would see a 50% reduction in nett CO2 atmospheric concentrations.
But it doesn’t stop there
Several cycles take place to remove CO2 from the atmosphere, not least by dissolution in rain, combination with minerals on land and ultimately flowing into the oceans and deposit as sedimentation.
True, some subduction at plate boundaries would recycle carbonates through volcanisms and back into the atmosphere, but over time a gradual reduction of CO2 takes place.
As carbon life-forms take up even more carbonates to build homes for themselves, then die and bequeath these homes to the sea floor as sediment, more and more carbon is tied up as rock.
In Potential Errors in Estimates of Carbonate Rock Accumulating through Geologic Time (pay walled here), Hay calculates that today the continents contain at least 2.82 × 106 km3 of limestone, which are the remains of deposits over the past 570 million years that have not been washed to sea or subducted back into Earth’s interior. This is equivalent to a CO2 atmospheric pressure of 38 bar. If we add the carbonates found on the ocean floor, the equivalent CO2 atmospheric pressure rises to 55 bar.
Adding all this together more than accounts for a 90% CO2 concentration at 90 Bar being reduced over time to a much lower say 20% CO2 and 4 or 5 bar – just right for the pterosaurs to take wing.
Whilst all this was going on, plant life took a turn all of its own.
Evolving from the primordial soup, cyanobacteria initially removed Iron from the oceans and created Oxygen. It was this oxygen that then led to multi-celled life-forms and ultimately diverging between the plants and animals such as protozoa, fish, land animals and dinosaurs
Above: A laminated rock formed by the growth of blue-green algae (i.e., cyanobacteria)
So, if we now accept that 100Mya, there was an atmosphere with about 20% CO2 and say 5 Bar pressure, would plant and animal life have thrived under such conditions? Do we even know that these values were anywhere near accurate?
If we believe the aeronautical engineers, pterosaurs needed a denser air to succeed – that estimate is between 3.5 and 8 times current density (=pressure). So that part of our assumption looks OK on the face of it – yes air would have had to have been more dense.
And what of O2?
Well perhaps it comes down to some type of proxies – yes our old friends !
We do know that there were some pretty impressive flying insects around back then, and it seems well known that insects breath through their “tracheae” – narrow tubes – rather than having lungs or gills. These tracheae transfer O2 directly from the surface of the skin into the organs of the body. The ability to uptake O2 is governed by the length of the tracheae. Big insects naturally have longer tracheae, so uptake less O2 – that is unless O2 is served at higher concentrations and/or pressure so the body can get all the O2 it needs.
Since we know there were huge dragonflies and cockroaches around during the Carboniferous and Permian (300-250Mya), it seems to support a postulation that O2 concentrations were of the order 35% back then, compared to today’s 20%.
Meganeura, a genus of dragonfly from about 300Mya had a wingspan of up to 65cm (2’1”), and Meganeuropsis Permiana from about 250Mya grew even larger – up to 71cm (2’4”).
Neither survived to compete alongside the pterosaurs however. Many believe the concentrations of O2 dropped too low to allow such mega fauna to survive beyond the Permian.
In Part II, I will pick up on your suggestions from comments here, and look to what has happened to reduce Atmospheric Pressure from 5 Bar to 1 Bar, and why it continues to drop today.
I try to imagine Rex walking 50 meters underwater.
The scientific community is still stuck in this 19th century mindset of imagining that dinosaurs had to be slow, dim-witted, cold blooded and in every way inferior and less efficient than us hominids, the pinnacle of evolution.
The psycology behind this in the 19th century was a little sinister. It was ideologically necessary to show evolution as a continuous improvement, from inferior to superior bodies and physiology. The late Steven Jay Gould has written lucidly to demolish this fallacy – the “quality” if you like of organisms by the late Cambrian was already no different to today. Gould´s premise of “contingency” is that the species that survived and continued did so largely by good luck in relation to changing climate and geography on earth.
What made this “upward march” paradigm sinister in the 19th century was that it was extended to human races – in those non-PC days scientist spoke quite openly for instance about africans being racially inferior, it even became a science in its own right, us Caucasians were supposed to show a higher degree of neoteny (adult retention of embryonic/juvenile traits) than the bigger and more robust afros. What then arose was an embarrasing problem in that – by the same yardstick – the Chinese and Asians were superior (more neotenic) than us Europeans. (So the hypothesis was quietly shelved!) Anyway for the full story on this its best to read SJ Gould himself.
But our need for dinosaurs to be lumbering slow and inferior is still deep rooted in modern society, the term “dinosaur” is used as a metaphor for something becoming dated and uncompetitive, in a business environment for example.
Thus in this discussion of pterosaurs we have to make the air denser and give them more oxygen – in defiance of the geological record on the palaeo atmosphere. Give them a handicap;
The extent to which the reality is the stark opposite to this popular idea is extreme to the point of shocking.
In fact the Jurrasic Park films, for all their flaws, actually got it right in the sense that dinosaurs transported to our time quite likely would pose a mortal threat to all animal life larger than a rat or hedgehog.
As has been pointed out above, birds are dinosaurs. It follows that dinosaurs are birds. OK some with knowledge of taxonomy will point to exceptions, but the relatedness to birds included one very important physiological factor: birds – and dinosaurs – had a lung breathing system about 10 times more efficient than our own. Yes – TEN TIMES.
How and why is this? First, our lungs are tidal. The air comes in and goes out by the same trachea, bronchi and bronchioles down to the gas exchanging alveoli. Unfortunately – and sorry to disappoint the 19th century evolutionary supremicists – but this design is CRAP. The diffusion situation means that the O2 concentration gets lower and lower deeper into the lung and reaches its minimium where it is actually needed, at the gas exchanging alveolar sacs.
Birds by contrast have lungs in which the air flows ONLY ONE WAY through the tubes. It does this by a complex system involving air spaces within the bones. But it means that air crosses the equivalent of gas exchanging alveolar surfaces at essentially atmospheric concentration. Engineers among you will appreciate the significance of this.
This hugely more efficient bird breathing system is why they can fly. And it is also why pterosaurs could fly. (If not technically dinosaurs, they derived from the Triassic Therapsid line and thus probably had a similar physiology to the dinosaurs.) Recent research (published in Anatomical Record about 2-3 years ago) has shown that many signs of dinosaur anatomy confirm this avian type of lung system. this includes ribs all the way down the body (ever seen a bird with a 6-pack?) and thus a rigid torso. With the more efficient one-way breathing system, the lung does not need to inflate and deflate anything like as much as our tidal lungs. In birds there is only a small membrane at the back of the torso which moves in and out with breathing – this is where you stick your fingers in when you are gutting a bird.
It is also why dinosaurs and pterosaurs had much superior cardiovascular efficiency to us – they would have quite literally run rings around us. And maybe gutted us and eaten us for Christmas dinner.
And pterosaurs with their one-way breathing anatomy would have no difficulty in flying thank-you very much, no need for fictitious atmospheres.
On the matter of flying reps, here is some comparative numbers from the modern R/C proxies with a “standard” wing, fuselage and some kind of empennage: 5-10 oz/sq.in of lifting surface floats like a leaf more or less. Your basic handlaunched flat-bottomed 2 channel glider. Soars like an eagle, flies like a pig. 10 15 oz/sq.in, nice performance range for aerobatic gliders, and high-dihedral powered trainers. Good power-off flight characteristics for gentle landings, not much drag compensation without power unless aerodynamically very clean. 15-25 oz/sq.in – high performance powered aircraft at the high end, slope soarers and clean aerobatic gliders at the low end.
PTEROSAURS WERE NOT DINOSAURS.
Sorry to shout, but it’s a schoolboy error (quite literally), painful to the palaeobiologist.
MacCready’s Q. northropi “model” was not very realistic, and proved little.
Some Pterosaurs may have been competent walkers:
http://en.wikipedia.org/wiki/Pterosaur#Flight
Evidence of accretion argues that the mass of Earth must have been smaller in the remote past. Some combination of weaker gravity and heavier atmospheric pressure seems to be the simplest and most plausible explanation for pterosaur flight and dinosaur mobility.
If you want something to cheer you up, have a read of “Causes and timing of biosphere extincions” By Franck et al, 2006.
http://www.biogeosciences.net/3/85/2006/bg-3-85-2006.pdf
Figs 4 and 5 above confirm that CO2 is gradually being removed from the atmosphere; Franck et al. conclude that CO2 starvation will be the eventual cause of extinction of life (first multicellular, then bacteria° in around 1 billion years time – not heat.
The implications of this in regard to the CAGW hypothesis and human emissions of CO2 are too obvious to mention.
A fan of *MORE* discourse says:
June 2, 2012 at 2:18 pm
“Alarming Explanation #1: Atmospheric mass is decreasing because the H2O content of the atmosphere is decreasing with increasing global temperature; the lessened cloud cover contributes to positive climate-change forcing.”
I think you should read the alarmist bible, IPCC AR 4, again, especially the section about positive water vapor feedback, if they have mentioned that. (They should, as it’s essential to their alarmism)
Then, read about Miskolczi’s theory.
Not sure how to explain a 5 fold loss in atmospheric mass, even given the geologic time involved.
But here are some additional considerations related to a five fold increase in atmospheric pressure: If the organism living in the atmosphere used hemoglobin to transport oxygen, it is likely that its physiology is at least similar to today’s mammals and reptiles.
1. Breathing effort is a function of gas density. A five fold increase would require a very powerful respiratory system. Any evidence for that in the fossil record?
2. O2 at partial pressures exceeding 1 to 2 Bar has been shown to be toxic to today’s organisms. It attacks and destroys enzymes and central nervous system [CNS] cells. A 5 Bar atmosphere with 21% O2 would require an entirely different CNS physiology for Jurassic reptiles. A higher percentage of atmospheric O2 only compounds the problem.
3. Inert gasses and CO2 have demonstrated significant narcotic properties at any elevated partial pressures. CO2 is 25 times more soluble in lipids as N2 and is considerably more narcotic than the N2 that is responsible for nitrogen narcosis in SCUBA divers. 5 bars worth of elevated partial pressures would result in considerable narcotic effects unless Jurassic physiology was somehow very different than today’s organisms. The problem is compounded for air breathing marine organisms that would swim to any depth.
Given the above physiology constraints of a denser atmosphere, I think there is a larger problem with a 5 Bar atmosphere and life as we understand it.
With respect to Philip Foster’s comment/question on the relationship between lift and drag: Lift and Drag are linearly proportional to atmospheric density. They both increase or decrease proportionally with a change in density [at low airspeeds – we aren’t concerned with high speed compressibility effects in pterodactyl flying]. What is gained by a density increase is the ability to generate the same lift at lower airspeeds [fly slower].
So I vote with Philip, no significant aerodynamic benefit to having a denser atmosphere except slower takeoff and landing speeds. Perhaps useful depending on the reptile’s wing characteristics.
http://wright.nasa.gov/airplane/lifteq.html
http://wright.nasa.gov/airplane/drageq.html
1. I think the question of atmospheric pressure several hundred million years ago has nothing to do with the ~0.1% change measured on century scale.
2. You should give some thought to how global annual mean atmospheric pressure is measured. It may have the same problems global annual mean atmospheric temperature has. That is, you can calculate annual means for an ever changing set of measurement points, distributed unequally on the surface, but a great many assumptions go into transforming it into a true mean.
Andi, please convert the atm. PRESSURE loss into atm. VOLUME
loss in ppmv and compare it to the 2 ppmv atmospheric gain by
our man-made addition(emission) of CO2/GHG…..
The present CO2-volume is soon reaching 400 ppm, we thus
INCREASE the atmospheric pressure with the
weight of man-made emissions!
You talk about pressure/volume LOSS, whereas we have
a man-made pressure GAIN with the volume of GHG emissions….
Plus, CO2-emissions are heavier than air, also INCREASING
the total atmospheric pressure…..The galance would be the
total volume loss into space, being decomposed on top of the
atmosphere by UV and solar wind, whith the wind pressure blowing
the top off (2 recent posts on that….)
JS
This has been posited before:
The Thick Atmosphere Solution: http://dinosaurtheory.com/thick_atmosphere.html
The Thick Mesozoic Atmosphere
In the article above it is written: “—- the current accepted mean value is around 1013.25 Mbar. So any warming observed over the past 90 or so years should be ruled out as causation – warm or cold the air weighs the same (within reason)” –
First let me, if I may, start with the figure 1013.25 Mbar which looks like a very precise value but may not necessarily accurately reflect the weight of any air at the Earth’s surface. That is because 1013.25 is the international Altimeter setting for aircrafts flying on instrument settings in open air-space. – In short, in order to keep a precise altitude during instrument conditions (high traffic, high speeds – dense fog) an aircraft needs to have an Altimeter that can be accurate to two decimals. (Just ask Burt Rutan how long this has been the case – I can only guess it has been for at least half of the 90 years of warming mentioned above). –
Then the last bit: “– warm or cold the air weighs the same (within reason)” –
That statement is quite true as long as we weigh individual molecules/atoms, but the fact which is that as air warms it forms a pocket which increasingly occupies a larger space than does the air that remains cold(er), could also do with a mention. – By volume warm air is the larger and therefore lighter by volume.
The surrounding colder air resist the warming air’s expansion at all points and the result is that the pressure inside the said pocket increases. A “warm air pocket” can – and often does – grow to become a High Pressure System. – However, also take into consideration, as the warm air expansion is resisted the colder air pressure must also rise albeit a lot less as any ‘outside area’ is always larger than the corresponding ‘inside area’. It is also worth noticing that The Troposphere occupies a lot more space (in the form of height) in the tropical than it does in the far northern/southern hemispheres.
In the place where I live, the air pressure which – just a couple of days ago, in glorious Sunshine – hovered around 1025/ 1030 mbar has today dropped to 1002 mbar under a gray mass of rainclouds.
Needless to say the saturation rate is higher today than what it was two days ago, therefore I feel justified in saying that the “saturated air column” pressing down on my roof today weighs more than did the unsaturated or dry air that was present earlier and that therefore atmospheric/barometric air pressure has got more to do with cloud formation than it has to do with the weight if the vertical air column.
PS.
Maybe the graph depicting an observed fall in global annual mean atmospheric pressure since 1916 (from NOAA as you believe) is unintentionally depicting an increase in cloud cover (and therefore also quite accurate global temperature fluctuations 1916 -2006).
I wish this misconception could be put to rest. The similarities are few, differences many.
This false notion that helped get the entire CAGW scam rolling, along with an early, but mistaken belief that CO2 was responsible for the extremely high temperatures on Venus.
I think Sagan trumped Velikovsky with that one, the latter having predicted the high temperatures on Venus, but who turned out to be “right for the wrong reasons.” Or so they say.
After Hansen got wind of Sagan, he dropped dust, glommed onto CO2 as the heat devil on Venus, and turned his attention on Earth.
Much of the early CAGW scare featured the specter of Venus looming in Earth’s future, and Hansen continues to deploy it.
Rather than calling Venus “Earth’s Twin,” I’d suggest we use:
Earth’s Fairy Godmother
Rising atmospheric temperatures should increase the absolute humidity and therefore the mass of the atmosphere.
The likely mechanism decreasing the mass of the atmosphere over this timescale, is decreased water droplets (clouds) caused by decreased aerosols/particulates.
Its well documented that aerosols/particulates seed more persistent clouds.
Hoser,
Planes do not fly better in high humidity, nor is humid air more dense. Think about it, what are the molecular weights of O2, N2, CO2 and H2O ?
Sorry Hoser, strike that, I misread your post
thank you REP.
Question that comes to mind: What do we not know about the pterosaurs? We don’t know if they could fly, or if they could glide, or if they had scales or feathers. We only know that they appear to resemble some of the birds that live today. Some of the birds that live today do not fly, nor glide. Some appear to use their wings to simply maintain their balance, or sometimes to help them swim. As further muddying of the water, what’s to say that the pterosaurs weren’t some sort of swimming animal?
Therefore, though this subject provokes an interesting discussion, we really don’t know anything about pterosaurs except that they are all dead.
bean says:
June 2, 2012 at 3:43 pm
“…1. Breathing effort is a function of gas density. A five fold increase would require a very powerful respiratory system. Any evidence for that in the fossil record?”
=====================================================================
This may be the least of our fallacies, but I can’t agree–the denser the air and the higher the O2 content the easier and slower the breathing. Rather the evolution of vertebrate cardiovascular and pulmonary systems suggests perpetual oxygen starvation. Critters living under 5 atmospheres with high O2 content (before trees evolved) would never have needed vascular systems, hearts, gills, hemoglobin, lungs, better hearts, blood cells with no nuclei, etc.
It’s a mystery to me how anyone can take the diminishing gravity speculation any more seriously than Noah’s flood. Don’t you understand that if G decreased while the inertial properties of mass remained unchanged, all the orbits of planets and moons would be altered?
I bet thousands of aero engineers have claimed bumblebees break the laws of aerodynamics, just like ceramic engineers claim glass flows over decades, and creationists claim evolution breaks the laws of thermodynamics. If aero engineers had their act together we might expect that one or two of them would tackle the superbird myth–the ubiquitous fairy tale that a peregrine falcon can stoop at 240mph.
And what’s this nonsense about lunar tides sucking out the atmosphere? News to me.
What interests me about the pterosaurs is their fragility which suggests a lack of strong winds where they flew. –AGF
If the dunno sir atmosphere was five times as dense as today’s, wouldn’t those terrasaurs have to have five times as much horse; excuse me that’s T_Rex power to cope with the higher air resistance drag; and in that case, wouldn’t they be just too damned heavy to fly ?
Edit note;
“Deutrium” s/b Deuterium.
____
The dinosaurtheory.com site derives a pressure of about 350 bar during the Mesozoic, with about 2/3 of land dinosaurs’ weight buoyed up by the air, permitting e.g. brachiosaurs to walk out of water, and to pump blood to elevated heads without chained hearts etc. Pterosaurs could fly with great agility, sufficient to hunt and feed themselves.
There ain’t no difference nohow between pulling and pushing. Much of the transport is due to capillary action, the affinity of water for the tube walls. Dip a cloth into water and watch it soak upwards!
Increased pressure would of course increase the height water could be drawn up by pressure differences.
@bean at 3:43 pm
There is another important aspect of a denser atmosphere to flight. The Power it takes to stay aloft is a function air density, ie. Proportional to ρ^(-0.5) where ρ is air density.
http://web.mit.edu/16.unified/www/SPRING/systems/Lab_Notes/airpower.pdf
Eq. 16 shows that the energy expended to fly a distance is independent of density and directly proportional to weight.
Eq. 17 shows that the Power = Energy/time, is inversely proportional to sqrt(density), and proportional to weight^(3/2)
So for a 2 bar atmosphere, only needs 70% of the power as at 1 bar. 50% of the power at 4 bar than 1 bar.
Can we assume that Max Power from an organism is no better than proportional to weight? Pmax proportional to W^(x) where 0 < x <= 1. For simplicity, lets assume x = 1. Double the weight, you can double the Max Power. Double the weight and you need 2^(3/2) = 2.83 times power at constant density to stay aloft. It’s a losing game to get bigger if density is constant. However, if you double the air density and double the weight, you can restore the Max Power balance.
I conclude that the max weight of a flying organism is proportional to AirDensity^(1/(3-2x))
If x = 1, then Max weight is proportion to air density.
If x = 0.8, then Max weight is proportional to AirDensity^(0.71)
Doubling the weight implies more wing area, too, but it seems like in Eq. 17 that a larger wind area S cancels out for little change in power. But as the paper says,
“The Levenspiel et al 2000 paper is well worth a read…” HEY! Dr. Octave Levenspiel was my professor! Don Pettit was a classmate! Dr. Levenspiel could take any complex thing and turn it into a fun story, easy to understand. Yes, I’m an Oregon State Chemical Engineer. Woot!
Relax. Just the AO, again. http://virakkraft.com/AO-slp.png