Astronomers spot strange, bow-like structure in Venus' atmosphere

January 17, 2017 by Andrew Coates, The Conversation
Strange shape in Venus’ atmosphere. Credit: Planet-C

Venus is known both as the "planet of love" and the Earth's "evil twin". And although research suggests its environment is more hellish than romantic, there's actually a lot we don't know about our celestial neighbour. Now Japanese scientists have made a surprising discovery: an enormous, bow-shaped feature in the planet's cloud region which seems fixed to the slowly rotating planet. Clouds around it, on the other hand, whizz by at about 100 metres per second. So what is it?

Venus is almost as large as Earth but orbits closer to the sun. A spacecraft approaching the planet would see chevron-shaped structures in the clouds, due to the rapid "super-rotation" of its thick atmosphere well above the surface.

Before the space age, it was thought that Venus would be somewhat similar to Earth. Indeed, the expectation in science fiction was that the planet may support life, with thick vegetation under water-rich clouds. But spacecraft have shown us that Venus is lifeless and very different to our own planet – and the clouds are sulphuric acid. It has the hottest planetary surface in the solar system (720 Kelvin or 447°C – hot enough to melt lead), a thick atmosphere (92 times Earth's atmospheric pressure) and no protective magnetic field. Its rotation is slow – and the wrong way around (243 Earth days) – and it has hurricane force winds and strange vortices near the poles.

Although early Venus may have had some surface water, this gradually evaporated into the atmosphere due to the close distance to the sun. This led to a greenhouse effect in which the atmosphere got thicker, the surface got hotter, more water evaporated into the atmosphere and so forth. The water broke up in the rather than condensing onto the warm surface as oceans. Unlike Earth, carbon dioxide in the atmosphere could not be dissolved into the oceans, settling on the ocean floor as carbonates and cycled as carbon dioxide gas by volcanism. Instead, volcanism continued pumping gases into the atmosphere, building up the atmospheric pressure. The atmosphere of Venus now is principally , which is the reason the surface is extremely hot.

Clouds caused by gravity waves within meteorological disturbance. Credit: Glen Talbot

The early missions, including Mariner, Venera and Pioneer Venus determined the composition of the clouds and measured the atmospheric structure. The Russian Venera landers, the only craft so far to have landed in the harsh Venus environment, showed images of lava plains and volcanic terrain. Later the Magellan mission, which used radar to peer under the clouds, allowed mapping of the volcanoes and lava channels in detail – revealing a young surface with relatively few craters. This shows that the planet was resurfaced by volcanic activity about 500m years ago. More recently, Venus Express has shown possible signs of some volcanism within the last 100 to 10,000 years.

The super-rotation of Venus' atmosphere makes it very different from Earth. At the cloud level of 50-65km, where the varies between the Earth's surface pressure to 10% of that, the speed of rotation is up to 100m/s – about 60 times the speed of the planet's rotation. This is higher than a hurricane force on Earth. By contrast, Earth's fastest winds are only about 10-20% of the planet's rotation speed. Although the super-rotation is not fully understood, Pioneer Venus showed that the high speed reduces through the lower atmosphere, eventually rotating with the planet at the surface.

Perplexing planet

Enter the Japanese spacecraft Akatsuki, which was launched on May 20, 2010. The spacecraft is designed to study the structure and activity of the Venus atmosphere. After a difficult journey , it was successfully inserted into orbit at the second attempt in 2015. This, along with the first few results, were a huge achievement.

The new study reporting the discovery of the bow-shaped structure, just published in Nature Geoscience, is the most recent result of the mission. The wave was caught by Akatsuki's imaging instruments – looking in the infrared and ultraviolet parts of the electromagnetic spectrum. The astronomers analysing the data noted that the structure extended 10,000 km through the Venus cloud tops and persisted for a few days, then suddenly disappeared.

Gravity waves seen by Venus Express. Credit: NASA

Remarkably, the shape seems tied to the slowly rotating terrain below, particularly a high region called Aphrodite Terra, which is up to 5km high and the size of Africa near the equator. The structure persists in the rapidly moving, super-rotating winds at the cloud level. This is a bit like the flow of water flow around a submerged stone in a stream.

The researchers suggest that a stationary "gravity wave" (which is different from a gravitational wave) in the atmosphere might cause the effect. Gravity waves are generated at the boundary between the atmosphere and a surface, or between horizontal layers in the atmosphere, when the force of gravity opposes buoyancy (ability to float). An example on Earth is the wind waves on the sea – just between the atmosphere and the ocean. There are also over mountainous terrain, which form when air ripples move over a bumpy . Gravity waves on a larger scale can also be seen in the upper atmosphere between different layers.

Although smaller scale gravity waves have been seen near to ground level on Venus before, the scale of this new feature seems to be extremely large, probably the largest in the solar system. In fact it is unclear whether it is even possible for gravity waves to cause such a big effect.

The discovery illustrates that, although we can explain some of the features of the thick, fast Venus , it appears that low-altitude atmospheric dynamics are not fully understood yet. But we are slowly uncovering the planet's secrets and the latest study is certainly making waves.

Explore further: What is the weather like on Venus?

More information: Tetsuya Fukuhara et al. Large stationary gravity wave in the atmosphere of Venus, Nature Geoscience (2017). DOI: 10.1038/ngeo2873

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Chris_Reeve
2.4 / 5 (7) Jan 17, 2017
Re: "Remarkably, the shape seems tied to the slowly rotating terrain below, particularly a high region called Aphrodite Terra, which is up to 5km high and the size of Africa near the equator."

That's a potentially important observation because when the Venus Pioneer mission was sent there to generate evidence for a greenhouse effect, the surprise was the readings from multiple instruments that seemed to indicate a strong upward flux of heat from the surface.

Wal Thornhill has further noted the unusual radar signatures associated with these mountaintops.

It's not at all clear that the term "gravity wave" is appropriate here.
JongDan
5 / 5 (2) Jan 17, 2017
Lee wave, foehn wind. It's all been observed on Earth before.
cantdrive85
3 / 5 (5) Jan 17, 2017
Lee wave, foehn wind. It's all been observed on Earth before.

Not really relevant to the Venus observation. Lee wave and foehn winds are both down slope winds. The above describes vertically rising "wind".
NIPSZX
not rated yet Jan 17, 2017
I'm surprised that the cloud life theory wasn't pushed in this article. The TV specials on Venus always regurgitate the "life lives in the clouds of Venus" fake sounding theory.
jonesdave
4.2 / 5 (5) Jan 18, 2017
Wal Thornhill has further noted the unusual radar signatures associated with these mountaintops.

It's not at all clear that the term "gravity wave" is appropriate here.


And who the hell is Wal Thornhill? What did he get his PhD in again? Where is his publication record? When has he ever been right? Does he believe in Velikovsky's unscientific woo? Why the hell would anybody take any notice of what the eejit has to say?
Just a few questions, off the top of my head.
jonesdave
3.7 / 5 (3) Jan 18, 2017
From the paper (which I doubt any of the EU evangelicals have read):

"The latitudinal extent of the wave packet increases with height,
growing to a planetary scale at the cloud-top level, below which the
vertical wavelength is around 30 km. The maximum amplitude at
low latitude occurs just above the forcing. ***The resemblance of the
model result to the observation is remarkable***."

So, likely a gravity wave, then.
cantdrive85
1.8 / 5 (6) Jan 18, 2017
And as yet, jonesdumb is avoiding the electric discharge in plasmas discussion. Conveniently ignoring the facts again.
https://phys.org/...ace.html
jonesdave
3 / 5 (2) Jan 18, 2017
And as yet, jonesdumb is avoiding the electric discharge in plasmas discussion. Conveniently ignoring the facts again.
https://phys.org/...ace.html


And, as I'm sure I said elsewhere, and linked, lightning is nothing new in the ionosphere-magnetosphere.
Yawn.
jonesdave
3 / 5 (2) Jan 18, 2017
And as yet, jonesdumb is avoiding the electric discharge in plasmas discussion. Conveniently ignoring the facts again.
https://phys.org/...ace.html


I think you'll also find that what I said was along the lines of:
"Any burke who believes that the jets at comets are due to electric discharges either needs, or has already had, a lobotomy. Ditto anybody that suggests such a thing."

I think you'll find that I was right.
jonesdave
3 / 5 (2) Jan 18, 2017
I'll extend my above description to include:

Anybody that suggests that solar wind H+, at ~400 km/s, is going to combine with anything, is scientifically illiterate.
Anybody that claims that scientists are misinterpreting OH as H2O, despite over 20 previous years of unambiguous detections, is not only scientifically illiterate, but also a liar.

I could go on, and frequently have. So my point remains - why would anybody take the idiot Thornhill seriously?
cantdrive85
1 / 5 (3) Jan 18, 2017
"Any burke who believes that the jets at comets are due to electric discharges either needs, or has already had, a lobotomy. Ditto anybody that suggests such a thing."

And here is the relevant comment;

"The energy transfer process turns out to be very similar to the way lightning forms during a thunderstorm," said Bob Robinson, a space scientist at NASA Goddard and the Catholic University of America..Similarly, the solar wind striking the magnetosphere can build up a voltage difference between different regions of the ionosphere and the magnetosphere.

So, according to jonesdumb, the solar wind striking the coma of a comet cannot do the same thing. That plasma behaves differently than this plasma. Basically, according to jonesdumb, all plasma throughout the universe behaves dramatically differently than plasma in laboratories and the near earth plasmas of which we have in situ measurements. jonesdumb, I have to ask, where/why does this plasma not behave like plasma?
cantdrive85
1.8 / 5 (4) Jan 18, 2017
Anybody that suggests that solar wind H+, at ~400 km/s, is going to combine with anything, is scientifically illiterate.

Anyone who would make such a comment obviously doesn't have a clue regarding plasma physics.
JongDan
1 / 5 (1) Jan 18, 2017
Lee wave, foehn wind. It's all been observed on Earth before.

Not really relevant to the Venus observation. Lee wave and foehn winds are both down slope winds. The above describes vertically rising "wind".

Okay I don't remember what was the term for it, but I've been at some meteorology meeting where one group of scientists reported their measurements of upwards into the stratosphere spreading waves behind mountain ranges, they studied the Southern Alps on New Zealand and Scandinavian Mountains. I might try finding that paper for reference.
JongDan
1 / 5 (1) Jan 18, 2017
I think it was this group, Dörnbrack and Rapp.
http://onlinelibr...465/full
http://www.atmos-...016-765/
There's more to be found if you search for stratospheric mountain waves, but just so you know I'm not making stuff up I'm posting those two. Keyword might be DEEPWAVE (deep propagating gravity wave experiment), I think that's the name of their project.
jonesdave
3.4 / 5 (5) Jan 18, 2017
Anybody that suggests that solar wind H+, at ~400 km/s, is going to combine with anything, is scientifically illiterate.

Anyone who would make such a comment obviously doesn't have a clue regarding plasma physics.


So, come on sh** for brains. What is the 'energy' of a H+ ion at ~400 km/s? I'm guessing (not really) that it is around 1 keV. Care to disagree, sh** for brains? Like to tell us what that is going to combine with, sh** for brains? No, would be the answer to that, because both you, and the idiot Thornhill are as thick as pig sh*t. Yes?
jonesdave
3.7 / 5 (3) Jan 18, 2017
How can I put this simply? For people with the IQ of a rabbit? At 1 keV nothing is combining with anything. Get it? It is a non-starter. It is only believed by f**wits like the idiot Thornhill. He is scientifically illiterate. Quite why anybody else believes that bollocks is beyond me. It isn't happening. Understand?
jonesdave
3.7 / 5 (3) Jan 18, 2017
Anybody that suggests that solar wind H+, at ~400 km/s, is going to combine with anything, is scientifically illiterate.

Anyone who would make such a comment obviously doesn't have a clue regarding plasma physics.


No, anybody who would make THAT COMMENT does not understand plasma physics. IDIOT.
jonesdave
3.7 / 5 (3) Jan 18, 2017
Anybody that suggests that solar wind H+, at ~400 km/s, is going to combine with anything, is scientifically illiterate.

Anyone who would make such a comment obviously doesn't have a clue regarding plasma physics.


Please, enlighten us. There is probably a Nobel in this for you. Or not. Given that you are as thick as f**k. But please, carry on.
jonesdave
4 / 5 (4) Jan 18, 2017
Basically, according to jonesdumb, all plasma throughout the universe behaves dramatically differently than plasma in laboratories and the near earth plasmas of which we have in situ measurements. jonesdumb, I have to ask, where/why does this plasma not behave like plasma


Err, have you ever read anything about plasma effects at comets? No, didn't think so. Start here:
https://www.resea...0000.pdf

If you don't understand it just say so.
cantdrive85
1.7 / 5 (6) Jan 18, 2017
Err, have you ever read anything about plasma effects at comets?

Let's read;
"...or coma, extends more than a million kilometers into space, where it interacts with the solar wind..."
Hmmm, 400km/s solar wind "interacting".
" ...An "induced" cometary magnetosphere is a consequence of this interaction..."
A magnetosphere?
"...Cometary ion pick-up and mass loading of the solar wind starts to take place at very large cometocentric distances. Eventually this mass loading leads to the formation of a weak cometary bow shock..."
Ion pick-up and mass loading, seems as if that 400km/s solar wind is getting slowed down a bit.

"...Even closer to the nucleus, collisional processes, such as ion-neutral chemistry, become important...."
Isn't that special! Electrochemistry!

cantdrive85
1.7 / 5 (6) Jan 18, 2017
They go on;
"...Other features of the magnetosphere of an active comet include a magnetic barrier, a magnetotail, and a diamagnetic cavity near the nucleus..."
Just like the Earth, where the energy transfer is a type of electric discharge between the magnetosphere and ionosphere (diamagnetic cavity). According to you, that plasma behaves differently rhan this plasma.

"...X-ray emission from comets is produced by the interaction of the solar wind with cometary neutrals..."
That basically says the opposite of what you claimed.
jonesdave
4 / 5 (4) Jan 19, 2017

"...X-ray emission from comets is produced by the interaction of the solar wind with cometary neutrals..."
That basically says the opposite of what you claimed.


No, it doesn't. 'Heavy' solar wind ions, say O6+, charge exchange with cometary neutrals, say H2O (not there, according to Wal). O6+ 'steals' an electron from the H2O. It becomes O5+, and the H2O becomes H2O+. The O ion is 'excited' and, as it de-excites, gives off a specific narrow line emission in x-ray. This can be seen by various x-ray satellites (such as Chandra), and they know, due to the various narrow line emissions, which sw ions were responsible for the cx.
jonesdave
4 / 5 (4) Jan 19, 2017
^^^^ What the idiot Thornhill was saying (due to being scientifically illiterate) is that the sw H+ hurtles along at ~ 400 km/s, with an energy of ~ 1 keV, piles into an O-, and magically produces OH. Stupid scientists are then confusing this OH for H2O! Even though OH and H2O cannot be confused in an IR or sub-millimetre spectrum. In other words, as I said, he is either stupid, or lying. Probably both. Take your pick.
jonesdave
4 / 5 (4) Jan 19, 2017
"...Even closer to the nucleus, collisional processes, such as ion-neutral chemistry, become important...."


Yep, the aforementioned cx between cometary neutrals and the sw. No combination going on between sw ions and negative cometary ions (which are in very short supply!).
However, once the diamagnetic cavity forms, there is thought to be a re-combination zone, where previously dissociated cometary ions may recombine, as they are essentially stagnant. The solar wind, at this stage, is getting nowhere near the nucleus. As seen at Halley in '86 (not sure why this passed the idiot Thornhill by), and at 67P.

jonesdave
4 / 5 (4) Jan 19, 2017
Just like the Earth, where the energy transfer is a type of electric discharge between the magnetosphere and ionosphere (diamagnetic cavity). According to you, that plasma behaves differently rhan this plasma.


No, the diamagnetic cavity is not an 'ionosphere'. It is a cavity where the sw ions do not reach. It is also (by definition) an area where the IMF, frozen into the sw, does not reach. What exists in there are cometary neutrals (overwhelmingly) and some cometary ions. Given that the average time against photoionisation for H2O is about 10^6 secs., and that they travel at ~600 m/s, and the cavity is ~4000 km at Halley, and ~170 km at 67P, then you can see how overwhelmingly it is dominated by neutrals.

jonesdave
3.7 / 5 (3) Jan 19, 2017
An "induced" cometary magnetosphere is a consequence of this interaction..."
A magnetosphere?


An induced magnetosphere. As mentioned, and as previously figured out by Alfven, the IMF, frozen into the sw, piles up and then hangs up around the nucleus:
http://www.tandfo...9i1.9064

This is essentially what creates the diamagnetic cavity, as ion-neutral friction hangs it up. As also seen in the AMPTE artificial comet (i.e. an exploded canister of barium/ lithium) experiments.
Travelling inward from the Sun, you will experience the normal IMF at about 2nT, then you hit the pile up zone, where it will jump to about 20 nT, and then you'll be in the cavity, 0 nT.
jonesdave
3.7 / 5 (3) Jan 19, 2017
Ion pick-up and mass loading, seems as if that 400km/s solar wind is getting slowed down a bit.


Err, yep. As has been known for a long time. Not getting within ~1500 km of 67P in October 2015. Once the comet starts to outgas at a reasonable level, the sw will be deflected at greater and greater angles. Eventually, this will reach ~90 degrees, and various boundaries will form. Ergo, all the H2O, and other volatiles which were exiting the comet, cannot possibly have anything to do with the solar wind. Ditto, in 1986, at Halley, at much greater distances. Again, this seems to have passed Thornhill by.
jonesdave
3.7 / 5 (3) Jan 19, 2017
And where the solar wind is encountering cometary ions at half rat power, what it is 'seeing' are overwhelmingly water group ions. That is, H3O+, H2O+, for the most part. It is not going to be combining with those, for obvious reasons. Any OH it encounters will be OH+. Same problem. This aside from the very easy maths, which shows that there are many orders of magnitude too few ions in the solar wind to make Wal's nonsense a reality, even if it were possible. Which it isn't. Ditto the equally idiotic claims of a certain Dr. Anariba, about proton implantation. Not enough protons, and the sw isn't reaching the nucleus when the comet is most active.
Dead in the water. Literally.
jonesdave
4 / 5 (4) Jan 19, 2017
So, to summarise this little off-topic excursion:
Wal is woefully ignorant of some fairly basic cometary science. Stuff that was already well known when he and Talbott wrote their ludicrous 'electric comet' poster.
He doesn't really care about this, as his acolytes will accept what he says without question, and will not bother to read the scientific literature that shows him to be wrong.
It is why he never mentioned the solid ice excavated at Tempel 1. Or the gazillions of chunks of ice seen around Hartley 2: https://science.n...nowstorm
As always with the fruitloop Thornhill, it all comes back to Velikovskian woo. He needs comets to be rock (even though they demonstrably aren't), so that he can have them being formed from dirty great chunks of the stuff being blasted off of planets by interplanetary lightning bolts, during a fairly recent game of interplanetary billiards.
Too silly for words.

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