Everyone see things in the clouds. People, animals, Christ on the cross, UFO’s, angels, and even schizophrenically imagined chemical attacks by contrails. You name it, somebody has seen it. So when I was prodded with a news item that said “new cloud type defined” I was thinking “uh oh, here we go again”. It is a lot like cyclomania, as humans tend to assign patterns to randomly ordered observations of nature. Looking for meanings in the clouds isn’t much different than looking for meanings in the alignments of the stars and planets.
From ChattahBox and The UK Telegraph:
Click for a larger image
(ChattahBox)—Meteorologists around the world have taken notice of a new storm cloud on the horizon, literally. And if they have their way the dark and choppy cloud will take its rightful place among its more famous cousins, cumulus, cumulus, cirrus and nimbus.
Cloud gazing Meteorologists first noticed the stormy and billowy formation floating over the Scottish Highlands and above Snowdonia, Wales. The unique gray storm cloud was also spotted over Australia, the cornfields of Iowa and high above the Arctic Sea off the coast of Greenland.
A group in England dedicated to cloud watching, the Cloud Appreciation Society, became quite excited when viewing numerous photos of the new storm cloud floating in the atmosphere.
The Cloud appreciators describe the cloud as “…a bit like looking at the surface of a choppy sea from below,” said Gavin Pretor-Pinney, founder of the Cloud Appreciation Society, and the first man to identify the new cloud.
The Royal Meteorological Society has named the new cloud, “Asperatus,” the Latin word for rough, since the cloud has the appearance of a rough, choppy ocean.
The Royal meteorologists are now attempting to have Asperatus officially recognized by the UN’s World Meteorological Organization in Geneva to have it included in the International Cloud Atlas.
If the meteorologists are successful, this would mark the first time a new cloud was officially recognized since 1953.
I have seen clouds like this, but did not see them as being a new classification. Thus a little trouble with the idea of making an entirely new classification for this cloud, a sub classification perhaps would be more appropriate, especially since this cloud does not appear to inhabit the middle and higher levels of the atmosphere.
So for “asperatus” I could see maybe “stratoasperatus” but not “altoasperatus” since there is no evidence of them at the high altitudes, and clouds at that level tend not to be rough edged.
I actually hope WMO doesn’t accept this ploy for attention by the Cloud Appreciation Society, if they do, it could open an avalanche of new cloud classification applications, we may see pitches of the most absurd kind.
There’s two wave-systems (mountain lee waves) interfering in that photo, which often have associated rotor clouds this looks like rotor to me.
page48
May 31, 2009 2:08 pm
The Cloud Appreciation Society???????????????
Oh, man………………….
John Egan
May 31, 2009 2:09 pm
Gemini –
You will get new ideas from the sky and become fabulously wealthy.
Bulaman
May 31, 2009 2:10 pm
We had a stunning example of this in January inland from Timaru. Started out as mamatus and then developed the swirls and shears in the large scale. Never seen it before tho.
Brian Johnson
May 31, 2009 2:14 pm
Surely the Dorset Doughnut is actually a chemtrail disappearing up its own orifice?
Pops
May 31, 2009 2:17 pm
That’s a Photoshop image if ever I saw one.
Pops
May 31, 2009 2:18 pm
Let’s just dump the u-tube age and get back to reality… please.
Cold Play
May 31, 2009 2:18 pm
It’s the Thirty First of May not April the First?
geo
May 31, 2009 2:18 pm
Clearly AGW is producing new kinds of angry clouds. These ones undoubtedly will be discovered to accelerate positive feedback.
MarkB
May 31, 2009 2:19 pm
[snip – cumulonimbus mammatus is the word you are looking for]
With an apology to William Wordsworth:
I wondered lonely toward a crowd
When all at once I saw a cloud
Above the lake, above the trees
Can we name it Asperatus, please
Sang the CA and RM societies
Fluttering and dancing in the breeze.
Of course, due to global warming…or HE being manifested among the clouds (of course dark ones).
Perhaps, those cloud were a characteristic of Maunder Minimum, so they could be named Svensmark-Asperatus Clouds.
I have two new candidates, Cirrostreakus (formed from the spreading out of contrails), and Cumulosteamus, that visible low level cloud seen condensing near power plants.
F.Ross
May 31, 2009 3:29 pm
Asperatus?
Give me a break! These people have way too much idle time.
Raven
May 31, 2009 3:46 pm
Off Topic:
I have noticed that 90% of the adds on this site are from alarmist organizations or groups (I just got a 400×300 flash ad peddling carbon offsets).
A not-so-subtle statement on the amount of money that can be made peddling alarmism. Maybe it is time to stop worrying about “Big Oil” and start worrying abount “Big Green”.
SL
May 31, 2009 3:48 pm
I can’t believe no one has said this yet! They look like flying sheep to me. Or maybe ducks… or kittens…
We now return you to your regularly scheduled programing.
Ron de Haan
May 31, 2009 3:50 pm
Clouds often mirror the landscape.
In this case we see lenticularis clouds at the horizon.
These clouds mark the rising of the air current when the wind meets a mountain or mountenous terrain.
Some times these clouds also occure when a windsheer takes place above condensation level.
You would see a cumulus cloud with a Lenticularis cloud on top of it.
If the air is turbulent, the underside of the cloud would take the form of a mamatus.
No need for futher classifications.
We have seen it all.
You’re right Ralph Ellis.
This glider pilot has flown in wave numerous times. Often smooth air as you get a magic escalator ride to high altitudes. Then the clouds look smooth. Sometimes there is turbulence and I’ve seen clouds like those in the photo. You can then see the turbulence cells moving through the cloud. Rotor is usually much more ragged looking.
Chris D.
May 31, 2009 3:58 pm
Looks more like somebody had a little fun with their image editing software…
crosspatch
May 31, 2009 3:59 pm
Wonder what kind of clouds they have in New York? A frost warming is up for most of the state until Monday. Pretty late in the year for frost.
crosspatch
May 31, 2009 3:59 pm
Oops. mean frost WARNING … freudian?
Robert Morris
May 31, 2009 4:03 pm
The doughnut should definately be named after our own dear Britannic Prime Minister, Altostratus Brownholio.
Molon Labe
May 31, 2009 4:08 pm
I’ve seen these wavy cloud formations in Columbia, SC and Boulder, CO. I always assumed it was a manifestation of the Helmholtz Resonance.
PaulH
May 31, 2009 4:09 pm
I saw some suspicious looking contrails in my coffee this morning. Is there a Coffee Cloud Appreciation Society out there who could explain this to me? ;->
Sandy
May 31, 2009 4:14 pm
Yup not really rotor cloud, more like the wave-system in the distance petering out above stratus and thinning it without breaking through.
>>Asperatus?
>>Give me a break! These people have way too much idle time.
No, no, these people just have no contact with society or the real world. They meant to call it Aspergeratus, but cannot spell either. http://en.wikipedia.org/wiki/Asperger_syndrome
.
Gary
May 31, 2009 4:23 pm
The image reminds me of a Van Gogh painting. As for naming new cloud types, I’m reminded of a quote from a biologist about the difficulty of defining species: “Nature mocks human categories.”
Speaking of clouds…
Here’s a link to an article on The Resilient Earth about a new study on cloud formation, especially low level clouds. It looks like this new study is questioning some of the assumptions about clouds that have been made by climate modelers. Check it out: http://theresilientearth.com/?q=content/airborne-bacteria-discredit-climate-modeling-dogma
Wansbeck
May 31, 2009 4:50 pm
I’m surprised that the present cloud classification hasn’t already been discredited by models as it was devised by the Quaker businessman and AMATEUR meteorologist Luke Howard who liked to do a bit of cloud spotting while walking between properties in London.
As we all know, there is no place for amateurs in climate ‘science’.
Mike Smith
May 31, 2009 4:56 pm
We see those wave clouds in Kansas all the time.
Wansbeck
May 31, 2009 5:06 pm
A bit OT but a quote from a recent excellent 3 part series tucked away on BBC4 simply titled ‘Weather’.
“Hadley was an amateur, he was so amateur that no image exists”.
How sad and how times have changed where amateurs, who once made huge leaps in understanding, are now denigrated.
John
May 31, 2009 5:55 pm
That is an HDR (High Dynamic Range) image…basically 2+ images set at different exposures combined into one. Allows for optimum lighting on the entire subject. Normally if you shot a picture of a tree the sky would be whited out (example), but if you take two – one of the tree and one of the sky from a tripod, you can combine them and get a fancy picture. HDR images look terrible IMO and are misleading (as is this image). Just another digital photography gimmick. You can do it with traditional negatives as well, but it takes a lot of skill.
On another note…looks like gravity waves.
TIM CLARK
May 31, 2009 6:02 pm
Are you searching for that perfect intimate gift. One that will remind your significant other of you every time they look in the sky. Well, I have the answer for you. Name a cloud after them. Yes, for only $50, the http://cloudappreciationsociety.org/ will name a unique cloud formation after your loved one. Please click on the donate icon in the right hand tray and you will always have your love displayed for all to see in the sky.
ROM
May 31, 2009 6:07 pm
Along with Mike Borgelt, a well known glider pilot, I also fly gliders.
I have not seen actual clouds as depicted but the conditions for the turbulence cells as Mike calls them, that form the cloud type depicted is very common.
On a lot of cloud free summer days in Australia this type of formation is clearly seen at the inversion levels or top of the convective layer where the identical to the pic undulations are often clearly marked by haze and sometimes smoke.
Sometimes the higher points on the undulations are marked by small, vaporous and momentary cumulous clouds.
When flying in clear skies on cloud free days, experienced glider pilots often use these undulations when they are marked by haze or smoke to find lift areas or to minimise flying in sinking air while flying long distances cross country.
The above phenomena occurs across the flat open terrain of Australia and does not have any connection with mountain wave formation.
The only unusual thing about that pic is that the undulations are marked by a cloud layer.
A stratified smoke layer at the top of the convective layer will often show the same characteristics as the pic.
Glenn
May 31, 2009 6:21 pm
It’s obvious why the RMS is playing “what figures can you see in the clouds”. From the article:
“Professor Paul Hardaker, the Chief Executive of the Royal Meteorological Society, said: “The process is a long and convoluted one to get through, but we believe there is a good case for this cloud to be added.
“There would probably need to be quite a lot of heat around to produce the energy needed to generate such dramatic cloud formations. They are quite dark structures so there must be a lot of water vapour condensing in the cloud.”
“A lot of heat around”. Hint hint wink wink.
Jeff Alberts
May 31, 2009 6:22 pm
And if they have their way the dark and choppy cloud will take its rightful place among its more famous cousins, cumulus, cumulus, cirrus and nimbus.
I guess cumulus are so important they deserved mentioning twice.
Douglas DC
May 31, 2009 6:25 pm
With every one else-I’m an old mountain pilot.I have flown Saliplanes and launched them in all kinds of weather.This is a Mountain wave. Period.
Next someone will tie them to Chemtrails….
Claude Harvey
May 31, 2009 6:33 pm
I believe what they’re calling the Dorset Doughnut is actually an entirely new cloud formation. How do I petition for said classification? I propose to name the discovery “rectumulus”.
stumpy
May 31, 2009 7:14 pm
Looks like the “nor west arch” to me. Happens when air rises over the alps, looses its moisture and drops down the otherside onto the plains as warmer dry air. This occurs a few kms from the alps before reaching the sea.
stumpy
May 31, 2009 7:24 pm
http://en.wikipedia.org/wiki/Nor'west_arch
Its not common, but on occassion the nor’west arch appears as above like a sea of undulating waves, quite immpressive when the sun is low and it catches and highlights the waves.
just have to say this: I have been seeing the amounts/types of clouds like I saw when I was a wee lad in the 60s and some early 70s.
that is all, nothing to see here, move along folks move!
Joel
May 31, 2009 8:27 pm
Looks like a nimbostratus. Whats wrong with calling it Nimbostratus Asperatus? Like you said, it seems a little more realistic to put it in a sub-category instead of a whole new category all together. It doesn’t seem like there are enough instances of this cloud to justify a brand new category, but stranger things have happened haven’t they?
I’ve been a ‘cloud appreciater’ for years. I’ve also checked out their website – there are some pretty good photos there.
Shakespeare was also a cloud appreciater – or was it Hamlet? (According to my English teacher, this was Hamlet taking the piss out of Polonius.)
‘Hamlet: Do you see yonder cloud that’s almost in shape of a camel?
Polonius: By the mass, and ’tis like a camel…
‘Hamlet: More like a weasel methinks?
Polonius: Tis very like a weasel… etc. etc. etc…
rbateman
May 31, 2009 9:12 pm
So this Asperatus, it looks like an inverted Stratocumulus.
Harkening back to what the Fire Incident Information Officer said about the air-inversions being briefed to the Forest Service by NASA, GCR cause comes to mind. Some places not used to seeing them would be surprised.
Stratocumulus Invertus Minimus (Global Cooling Clouds). Hah !
Dene
May 31, 2009 9:22 pm
Smart and funny. I’ve literally been laughing out loud. Can’t wait to name a cloud after one of my fleeting girlfriends.
Whatever happened to cumulonimbus? Just last week I saw cloud formations that resembled layered scales – amazing. And no special relative topography.
Maybe Obama could name his 19th czar to study the phenomena, declare a crisis, blame global warming and develop a cloud stimulus package -stimulobogus.
Or, I’m thinking maybe… Nostrabamasiriusradionimbus… It’s a mystery as to what’s coming, but it’s dark and you have to pay extra.
Mark
May 31, 2009 9:48 pm
Umm, having been an observer in the Navy, I would have classified that simply as Stratus in a more or less continuous sheet or layer, or in ragged shreds, or both, but no stratus fractus of bad weather…or L6.
dmdoug
May 31, 2009 11:12 pm
They look just like the clouds photographed over Cedar Rapids, IA in 2006: http://www.kcrg.com/news/local/3195031.html
Weird Clouds Over Cedar Rapids, Iowa
What did the Iowa weather people say about the clouds? KCRG-TV’9s meteorologist Joe Winters said, “We’ll just call them wave clouds. That’s not actually a type of cloud. It’s just the way they looked. The atmosphere always has waves in it, like the ocean. We just don’t see waves often enough, and today we had the opportunity to do that. And it probably won’t happen again for a long time.”
wes george
June 1, 2009 12:11 am
This type of cloud isn’t that uncommon on the western slopes of the New England plateau in New South Wales, Australia, in winter. It is a kind of stratus probably contorted by mild thermals and contour of the hills.
The picture here appears so dramatic because of the thinness of the cloud layer and the lovely translucent light. I suspect our local aborigine tribes were looking at the same clouds 40,000 years ago, just as the Celts were in Scotland.
Keith Minto
June 1, 2009 12:35 am
Don’t be too hard on the Cloud Appreciation Society. If you have had a hard day at the screen go to the Photo Gallery,start the slide show and feel your blood pressure drop.
It is a slightly English harmless thing,like train spotting and you really need to get away from tall buildings to appreciate the complexity and subtle shape-change of clouds.I am lucky to live in inland Australia where the clouds can be truly spectacular compared with the coast.
The Asperatus clouds look to me like Mammatus with mountain wave turbulence and considering that Mamatus formation is a mystery, perhaps we should have an open mind about Asperatus.
oms
June 1, 2009 12:41 am
Well, oceanographers have been looking up at certain clouds for some years now and have sometimes commented that, “That looks just like the sea.”
Of course, we aren’t licensed to name clouds so I guess we gotta let that one go. Maybe we will name some sea states “cloudlike.” 🙂
The first picture reminds me of a phenomenon you often see in the Summer on the West Coast of France adjacent to the lower corner Noirmoutier Island. The clouds move longitudinally to the “stripes”. At the same time a lower level air current brings small feathery clouds across at a right angle. You get a similar perpendicular movements in the waves as the tide comes in.
E.M.Smith
Editor
June 1, 2009 2:19 am
Asperatus? As in “What asperatus do you use to measure the temperature?
Or “I have invented a new asperatus for humidity control?
(I can see no end of problems with this word and dyslexic kids, or those with speech impediments … )
An asperatus is an apparatus for aspirating your ah tus …
Or is it a person who aspires to us to inspire …
I think the cloud does not need a new name, but if it gets one, it will definitely need a new name…
Paul Coppin
June 1, 2009 3:51 am
he lighting has a lot to do with how they look, given the backlight from the low sun. If the sun had been in another position, they would have mostly just looked like plain stratus with a bit of wave shape. The layer is fairly thin. A group in England dedicated to cloud watching, the Cloud Appreciation Society, became quite excited when viewing numerous photos of the new storm cloud floating in the atmosphere.
The Cloud appreciators describe the cloud as “…a bit like looking at the surface of a choppy sea from below,” said Gavin Pretor-Pinney, founder of the Cloud Appreciation Society, and the first man to identify the new cloud.
Oddly, this bunch needs to get out more. Wave form clouds are well known, common, and ephemeral. They don’t need a new name – they already have one: “wave” clouds. If Pretor-Pinney and the RMS needs a latin name they can call them vacillostratus or vacilloform clouds (or stratovacillus, altovacillus, cirrovacillus or vacillocirrus, which is why they’re usually called “wave” clouds 🙂 . Keith Minto (00:35:22) :
Don’t be too hard on the Cloud Appreciation Society. If you have had a hard day at the screen go to the Photo Gallery,start the slide show and feel your blood pressure drop.
It is a slightly English harmless thing,like train spotting…
Please, don’t get me started on these “harmless” British fetishes. Thanks to a whacked-out Brit planespotter who couldn’t stay home, I fully expect to get yanked off a plane at any point due to somebody’s no-fly list >:(
“Rectumulus” LOL!
Paul Coppin
June 1, 2009 4:02 am
In looking at the various other pictures around of wave clouds, they all have the same characteristic: the layer is thin, allowing sunlight to define the wave density patterns. I think we are not looking at something new, just seeing something common under certain conditions and lighting. My own observations watching a setting sun through different cloud formations leads to seeing structure in cloud decks you can’t see when illuminated from above, or even directly from below.
Big Brother
June 1, 2009 4:13 am
Nothing to see here, folks!
Trust your goverment, your scientists and the big media journalists. They’re all paid professionals and they know what they’re doing.
Also, have a flu-shot – just in case – watch the news on TV – have some fluoridated water, antidepressants, aspartame, GMO’s and what have you – for they’re all good for you – and they’ve all been approved by Good Science…
Don’t believe me? Well, ask Donald Rumsfeld.
And BTW – stop buying more guns & ammo – instead join the Obama Corps and become a Civil SerfAnt.
And there’s no need for stockpiling food either – just have a food stamp – very low in calories!
With Whole Lotta Love,
BB
Ps. Don’t forget to pay your taxes – Wall Street and The Establishment really needs you and your money…
I want to officially petition for a new “looks like a horsy-stratus” cloud designation.
I can provide peer-reviewed evidence.
Mark
June 1, 2009 5:34 am
This is obviously George Bush’s fault.
Steve Moore
June 1, 2009 5:58 am
SL (15:48:51) :
I can’t believe no one has said this yet! They look like flying sheep to me.
Maybe Harold was successful!
Paul Coppin
June 1, 2009 6:06 am
E.M.Smith (02:19:07) :
Asperatus? As in “What asperatus do you use to measure the temperature
No, no! its a politically correct (available in white and coloured varieties) vegetable that makes you smell funny when you pee!
Paul Coppin
June 1, 2009 6:14 am
Apparently we’ve succeeded in collapsing the server at the Cloud Appreciation Society.
These wave clouds are apparently nothing more then thin low altitude stratus and nimbostratus forming in a fast moving air mass that happens to be close to terrain, which induces turbulence in what would be a more regular wave pattern, like non-breaking wave patterns in a stream over a rough rocky bottom.
“Altostratus Obamus,” of the idiomatic genus “pie in the sky.”
Paul Coppin
June 1, 2009 8:45 am
Digging a little deeper around the web, it would appear that this cloud form is already defined as stratus or altostratus undulatus, undulatus referring to the wavy bottom, and that the cited examples of “asperatus” at CAS are just good examples of the form. You might make a case for some examples being “mammatus undulatus”, depending on their genesis.
At any rate, another word doesn’t seem necessary or desirable, and they are certainly not “new storm clouds”.
George E. Smith
June 1, 2009 9:42 am
Maybe the cloud appreciation society ought to get their tails out of the pub and go out and look at some clouds.
We get these wave clouds all the time over silicon valley; they are so ho-hum.
Partly it is because the south Bay is hemmed in by some hills up to 4000 feet high, and then you get the daily vacuum cleaner winds coming through the golden gate; which play the valley like an organ pipe.
More importantly though, the bottom of those wave clouds are exactly like the bottom of the Arctic sea ice looks. (yeah I know it is crummy grammar).
There’s a picture on the table of contents page of the May 2009 issue of OPN; which is the Optics & Photonic News monthly bulletin. (Page 2)
It’s a USGS/NASA Landsat image looking donw on some mountains somewhere buried in cloud cover, where the whole area is an interfering wave pattern just like that bottom view above, and there is one sharp peak sticking up through the clouds, that is creating a turbulent diffraction pattern around the mountain that stretches down wind for about 15 times the diameter of the peak protruding through the cloud layer, with a whorl pattern that is cellular with cells about the size of the protruding peak.
Much more interesting than those apparatus clouds above.
George
TJA
June 1, 2009 10:27 am
“The unique gray storm cloud was also spotted over Australia, the cornfields of Iowa and high above the Arctic Sea off the coast of Greenland.”
So this particular and unique cloud travels around the world where it is spotted by different cloudspotters at different times? Or is the explanation that the writer has little grasp of the English language?
I rather like the storkostratus.
[snip] Reply: While that is not a [snip] site per se, and in fact is an anti [snip] site, in order to prevent discussions of [snip], I’m snipping the anti [snip] so as not to promote a reaction from the [snip] gallery. ~ charles the [snip] moderator.
Why not a post about the “New Age” creed or the “Green Agenda” ? to find out why “they” arrived at such preposterous idea of marketing “Global Warming” and why not another more intelligent and credible theory.
tallbloke
June 1, 2009 2:09 pm
Glenn (18:21:26) :
It’s obvious why the RMS is playing “what figures can you see in the clouds”. From the article:
“Professor Paul Hardaker, the Chief Executive of the Royal Meteorological Society, said: “The process is a long and convoluted one to get through, but we believe there is a good case for this cloud to be added.
“There would probably need to be quite a lot of heat around to produce the energy needed to generate such dramatic cloud formations.
Well the new name suggests itself then:
Nimbyus Nostradamus
The undulation pattern in the clouds might be from “gravity waves” (that’s different from “gravitational waves,” mind you). As several commenters have said, it occurs in the lee of mountains. Gravity provides the restoring force, hence the name. If that’s what these are, I recall reading about this effect in clouds 10-15 years ago in Physics Today.
George E. Smith
June 2, 2009 5:29 pm
“”” Tim Hamilton (04:45:31) :
The undulation pattern in the clouds might be from “gravity waves” “””
Tim, ordinary deep ocean waves are “gravity” waves; typically wind powered, and as you state, the restoring force on a displaced particle is gravitational, and the wave propagation is non dispersive, so the waves are simple harmonic motion, and all frequency components have the same wave velocity.
In water, you also have another restoring force, that is surface tension; which acts to try and minimise the surface area. But whereas the restoring force in gravity waves is proportional to displacement; (which is the differential equation definition of simple harmonic motion); the surface tension restoring force is absolutely independent of particle displacement, and depends only on the surface tension of water (Newtons per metre).
So surface tension waves are anything but SHM, and the are highly dispersive; so the short wavelength higher frequencies travel faster than the longer wavelenght lower frequencies.
Out in deep ocean waters; the surface tension is totally swamped by the gravity , so deep ocean waves travel non disp[ersively at the same velocity independent of wavelength.
But as the water shallows near shores, and beaches, the power in the gravity waves is reduced while the surface tension remains constant, so the surface tension waves start to dominate, and the higher frequencies run ahead of the lower frequencies, so the wave shape changes from sinusoidal for the SHM gravity waves to a sawtooth waveform, with the water poiling up at the front edge of the wave. Well eventually the high frequencies go right over the cliff, and at a given water depth, depending on the height of the waves, the wave leading edge collapses in the mess that beach bums and surfers travel the world to find.
The atmosphere doesn’t really have anything comparable to surface tension, so we never see those aparatus waves breaking on an upside down beach.
You do need air flow over the lip of the organ pipe (hills) to get the waves started; which is why you don’t see these over the flat midwestern cornfields; and notice that the waveforms are pretty nice symmetrical sinusoids, althoguht they are travelling in several directions and interfering with each other. The interference pattern is going to depend on the ridge line of the hills, and how many indivdual sources it creates; via passes, and peaks.
George
George E. Smith
June 2, 2009 5:33 pm
“”” Paul Coppin (08:45:55) :
Digging a little deeper around the web, it would appear that this cloud form is already defined as stratus or altostratus undulatus, undulatus referring to the wavy bottom, and that the cited examples of “asperatus” at CAS are just good examples of the form. You might make a case for some examples being “mammatus undulatus”, depending on their genesis.
At any rate, another word doesn’t seem necessary or desirable, and they are certainly not “new storm clouds”. “””
Paul, I suspect that the only difference between these aparatus clouds, and lenticular clouds, is one of persistence.
With lenticulars, they seem to form right over the generating peak, as a result of being forced up in altitude; till condensation occurs; but they re-evaporate, once the waveform dips lower, thus cutting off the lenticle.
George
George E. Smith–
Thanks a lot for the review of water waves. I knew that they had some real deviations from simple harmonic motion, but I hadn’t heard the reason explained so clearly before. The equations for water wave speed as a function of depth is rather complex. I’ve been trying to assign a student project to design a diffraction grating that would work with water waves, as well as a “lens” that would use a variable water depth to focus the wave. But it’s hard to get a usable effect in the ripple tank without going extremely shallow (~< 1/16"). Next time I try it, I'll have a good explanation of why it works at all, though.
George E. Smith
June 4, 2009 4:40 pm
“”” Tim Hamilton (08:52:00) : “””
Tim; One of my Second year Physics Lecturers; who taught the Sound and accoustics part of Physics; had a waves on water fetish.
It didn’t matter what subject he got started on; he could eventually bring it around to waves on water; whcih he loved.
Speaking of diffraction gratings; have you ever considered the idea, that a wave pattern on the surface of the water, is itself an accoustic diffraction grating.
It came to me once, while standing out on the Florida Keys Tarpon flats (on a boat) fly rod in hand, and waiting for a tide change that was calculated to bring the thundering herd of critters right past our stake out spot.
There was an almost imperceptible faint breeze blowing that created a slight wave pattern on the water, which was good for the tarpon to not be so skittish; but not so much wave as to slap against the hull, creating a noise which would blow them off our location.
Yet it wasn’t quiet; my guide commented about the interminable; but faint rushing sound in our ears; with no apparent source. So during a pregnant pause in the action; he asked me what the hell the noise was all about. That gave me an idea that set me bobbing up and down to get my ear as close to the water as possible (flats boats are very low freeboard).
Sure enough; as I changed my ear height, the sound changed its character.
Then I realized that the winds from far away were in fact generating a lot of noise all around us, but it was only audible for the sounds coming from a region close enough to us (but all around us) to be audible.
The somewhat chaotic surface wave pattern was acting as a surface diffraction grating of somewhat undefined but not totally random spacing, that was diffracting the essentially white noise into a frequency spectrum that was distributed roughly in verticaql angle from that apparent audible source radius.
So my up and down bobbing was simply scanning the sound spectrum, and listening to the frequency shift.
Needless to say; my guide (The Scientific American Recipient) was bloody impressed; and of course he made full use of his lecture episode to bamboozle his fellow guides at the bar apres fish. Darn sure we won ourselves a few free drinks at some of those bar meetings.
Yes waves are fun visual things for students; if you can turn just one on with them, it is worth the effort. You can show them interference and diffraction all in a shallow tank with simple apparatus; and hopefully get some surf bums to pay attention more often.
George
PS if you have some apparatus you can use with soap films to demonstrate the surface tension, and its independence of displacement, unlike a balloon skin. Like a couple of parallel wires with one movable end, so you can demonstrate that the work done is simply T x the change in area of the film.
Remember soap films are double sided so it is 2T x delta (a).
My grey matter is a little rusty so I don’t have a mental figure for the order of magnitude of T for modern soap films.
My wife and I saw this same formation over northern Dallas County just a couple of weeks ago. Most unusual — I had never seen clouds like that before.
Kathy
June 12, 2009 8:07 am
I just saw this where I live in Crestline, California, 5000 feet above see level. I had never heard of these clouds before and had certainly never seen them. I stood there watching them for a long, long time trying to figure out what they were because they were unidentifiable. Then I took a whole role of film. (:o)) Anyway, I’m glad to know these DO have a name, but now I wish that I understood what caused them to form.
There’s two wave-systems (mountain lee waves) interfering in that photo, which often have associated rotor clouds this looks like rotor to me.
The Cloud Appreciation Society???????????????
Oh, man………………….
Gemini –
You will get new ideas from the sky and become fabulously wealthy.
We had a stunning example of this in January inland from Timaru. Started out as mamatus and then developed the swirls and shears in the large scale. Never seen it before tho.
Surely the Dorset Doughnut is actually a chemtrail disappearing up its own orifice?
That’s a Photoshop image if ever I saw one.
Let’s just dump the u-tube age and get back to reality… please.
It’s the Thirty First of May not April the First?
Clearly AGW is producing new kinds of angry clouds. These ones undoubtedly will be discovered to accelerate positive feedback.
[snip – cumulonimbus mammatus is the word you are looking for]
How is this any different than an Altocumulus mackerel sky? I’m no meteorologist but that was the first thing that occurred to me when I saw it.
http://en.wikipedia.org/wiki/Altocumulus_mackerel_sky
BK
I remember seeing clouds like these back in the 1970’s in the SF Bay Area. These are nothing new and do not need a new classification.
Very nice images!
OT: Everyone interested in good science should check this out:
http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0005738
Ecotretas
With an apology to William Wordsworth:
I wondered lonely toward a crowd
When all at once I saw a cloud
Above the lake, above the trees
Can we name it Asperatus, please
Sang the CA and RM societies
Fluttering and dancing in the breeze.
Of course, due to global warming…or HE being manifested among the clouds (of course dark ones).
Perhaps, those cloud were a characteristic of Maunder Minimum, so they could be named Svensmark-Asperatus Clouds.
Choppy clouds?
That’s multiple wave formation produced by undulating terrain, as any glider pilot will tell you. Quite common over Wales too.
.
That is quite a picture. Reminds me of this:
http://www.vangoghgallery.com/catalog/Painting/508/Starry-Night.html
I have two new candidates, Cirrostreakus (formed from the spreading out of contrails), and Cumulosteamus, that visible low level cloud seen condensing near power plants.
Asperatus?
Give me a break! These people have way too much idle time.
Off Topic:
I have noticed that 90% of the adds on this site are from alarmist organizations or groups (I just got a 400×300 flash ad peddling carbon offsets).
A not-so-subtle statement on the amount of money that can be made peddling alarmism. Maybe it is time to stop worrying about “Big Oil” and start worrying abount “Big Green”.
I can’t believe no one has said this yet! They look like flying sheep to me. Or maybe ducks… or kittens…
We now return you to your regularly scheduled programing.
Clouds often mirror the landscape.
In this case we see lenticularis clouds at the horizon.
These clouds mark the rising of the air current when the wind meets a mountain or mountenous terrain.
Some times these clouds also occure when a windsheer takes place above condensation level.
You would see a cumulus cloud with a Lenticularis cloud on top of it.
If the air is turbulent, the underside of the cloud would take the form of a mamatus.
No need for futher classifications.
We have seen it all.
You’re right Ralph Ellis.
This glider pilot has flown in wave numerous times. Often smooth air as you get a magic escalator ride to high altitudes. Then the clouds look smooth. Sometimes there is turbulence and I’ve seen clouds like those in the photo. You can then see the turbulence cells moving through the cloud. Rotor is usually much more ragged looking.
Looks more like somebody had a little fun with their image editing software…
Wonder what kind of clouds they have in New York? A frost warming is up for most of the state until Monday. Pretty late in the year for frost.
Oops. mean frost WARNING … freudian?
The doughnut should definately be named after our own dear Britannic Prime Minister, Altostratus Brownholio.
I’ve seen these wavy cloud formations in Columbia, SC and Boulder, CO. I always assumed it was a manifestation of the Helmholtz Resonance.
I saw some suspicious looking contrails in my coffee this morning. Is there a Coffee Cloud Appreciation Society out there who could explain this to me? ;->
Yup not really rotor cloud, more like the wave-system in the distance petering out above stratus and thinning it without breaking through.
In upstate New York it’s snow clouds they’re seeing…
Saranac Lake, Adirondack Regional Airport
Lat: 44.39 Lon: -74.2 Elev: 1706
Last Update on May 31, 6:51 pm EDT
Heavy Snow Fog
33 °F
(1 °C)
Humidity: 96 %
Wind Speed: W 8 MPH
Barometer: 29.86″ (1012.0 mb)
Dewpoint: 32 °F (0 °C)
Wind Chill: 26 °F (-3 °C)
Visibility: 0.25 mi.
>>Asperatus?
>>Give me a break! These people have way too much idle time.
No, no, these people just have no contact with society or the real world. They meant to call it Aspergeratus, but cannot spell either.
http://en.wikipedia.org/wiki/Asperger_syndrome
.
The image reminds me of a Van Gogh painting. As for naming new cloud types, I’m reminded of a quote from a biologist about the difficulty of defining species: “Nature mocks human categories.”
I’ve seen the cloud above over hills in Texas for miles upon miles along I-10.
My favorite clouds low and dangerous looking are the mammatus:
http://www.nuestroclima.com/blog/wp-content/uploads/mammatus_06_1600x1200.jpg
Speaking of clouds…
Here’s a link to an article on The Resilient Earth about a new study on cloud formation, especially low level clouds. It looks like this new study is questioning some of the assumptions about clouds that have been made by climate modelers. Check it out:
http://theresilientearth.com/?q=content/airborne-bacteria-discredit-climate-modeling-dogma
I’m surprised that the present cloud classification hasn’t already been discredited by models as it was devised by the Quaker businessman and AMATEUR meteorologist Luke Howard who liked to do a bit of cloud spotting while walking between properties in London.
As we all know, there is no place for amateurs in climate ‘science’.
We see those wave clouds in Kansas all the time.
A bit OT but a quote from a recent excellent 3 part series tucked away on BBC4 simply titled ‘Weather’.
“Hadley was an amateur, he was so amateur that no image exists”.
How sad and how times have changed where amateurs, who once made huge leaps in understanding, are now denigrated.
That is an HDR (High Dynamic Range) image…basically 2+ images set at different exposures combined into one. Allows for optimum lighting on the entire subject. Normally if you shot a picture of a tree the sky would be whited out (example), but if you take two – one of the tree and one of the sky from a tripod, you can combine them and get a fancy picture. HDR images look terrible IMO and are misleading (as is this image). Just another digital photography gimmick. You can do it with traditional negatives as well, but it takes a lot of skill.
On another note…looks like gravity waves.
Are you searching for that perfect intimate gift. One that will remind your significant other of you every time they look in the sky. Well, I have the answer for you. Name a cloud after them. Yes, for only $50, the http://cloudappreciationsociety.org/ will name a unique cloud formation after your loved one. Please click on the donate icon in the right hand tray and you will always have your love displayed for all to see in the sky.
Along with Mike Borgelt, a well known glider pilot, I also fly gliders.
I have not seen actual clouds as depicted but the conditions for the turbulence cells as Mike calls them, that form the cloud type depicted is very common.
On a lot of cloud free summer days in Australia this type of formation is clearly seen at the inversion levels or top of the convective layer where the identical to the pic undulations are often clearly marked by haze and sometimes smoke.
Sometimes the higher points on the undulations are marked by small, vaporous and momentary cumulous clouds.
When flying in clear skies on cloud free days, experienced glider pilots often use these undulations when they are marked by haze or smoke to find lift areas or to minimise flying in sinking air while flying long distances cross country.
The above phenomena occurs across the flat open terrain of Australia and does not have any connection with mountain wave formation.
The only unusual thing about that pic is that the undulations are marked by a cloud layer.
A stratified smoke layer at the top of the convective layer will often show the same characteristics as the pic.
It’s obvious why the RMS is playing “what figures can you see in the clouds”. From the article:
“Professor Paul Hardaker, the Chief Executive of the Royal Meteorological Society, said: “The process is a long and convoluted one to get through, but we believe there is a good case for this cloud to be added.
“There would probably need to be quite a lot of heat around to produce the energy needed to generate such dramatic cloud formations. They are quite dark structures so there must be a lot of water vapour condensing in the cloud.”
“A lot of heat around”. Hint hint wink wink.
I guess cumulus are so important they deserved mentioning twice.
With every one else-I’m an old mountain pilot.I have flown Saliplanes and launched them in all kinds of weather.This is a Mountain wave. Period.
Next someone will tie them to Chemtrails….
I believe what they’re calling the Dorset Doughnut is actually an entirely new cloud formation. How do I petition for said classification? I propose to name the discovery “rectumulus”.
Looks like the “nor west arch” to me. Happens when air rises over the alps, looses its moisture and drops down the otherside onto the plains as warmer dry air. This occurs a few kms from the alps before reaching the sea.
http://en.wikipedia.org/wiki/Nor'west_arch
Its not common, but on occassion the nor’west arch appears as above like a sea of undulating waves, quite immpressive when the sun is low and it catches and highlights the waves.
Off Topic or maybe kind of On Topic, either way, I found this article very interesting … Airborne Bacteria Discredit Climate Modeling Dogma … quite a good read.
just have to say this: I have been seeing the amounts/types of clouds like I saw when I was a wee lad in the 60s and some early 70s.
that is all, nothing to see here, move along folks move!
Looks like a nimbostratus. Whats wrong with calling it Nimbostratus Asperatus? Like you said, it seems a little more realistic to put it in a sub-category instead of a whole new category all together. It doesn’t seem like there are enough instances of this cloud to justify a brand new category, but stranger things have happened haven’t they?
I’ve been a ‘cloud appreciater’ for years. I’ve also checked out their website – there are some pretty good photos there.
Shakespeare was also a cloud appreciater – or was it Hamlet? (According to my English teacher, this was Hamlet taking the piss out of Polonius.)
‘Hamlet: Do you see yonder cloud that’s almost in shape of a camel?
Polonius: By the mass, and ’tis like a camel…
‘Hamlet: More like a weasel methinks?
Polonius: Tis very like a weasel… etc. etc. etc…
So this Asperatus, it looks like an inverted Stratocumulus.
Harkening back to what the Fire Incident Information Officer said about the air-inversions being briefed to the Forest Service by NASA, GCR cause comes to mind. Some places not used to seeing them would be surprised.
Stratocumulus Invertus Minimus (Global Cooling Clouds). Hah !
Smart and funny. I’ve literally been laughing out loud. Can’t wait to name a cloud after one of my fleeting girlfriends.
Whatever happened to cumulonimbus? Just last week I saw cloud formations that resembled layered scales – amazing. And no special relative topography.
Maybe Obama could name his 19th czar to study the phenomena, declare a crisis, blame global warming and develop a cloud stimulus package -stimulobogus.
Or, I’m thinking maybe… Nostrabamasiriusradionimbus… It’s a mystery as to what’s coming, but it’s dark and you have to pay extra.
Umm, having been an observer in the Navy, I would have classified that simply as Stratus in a more or less continuous sheet or layer, or in ragged shreds, or both, but no stratus fractus of bad weather…or L6.
They look just like the clouds photographed over Cedar Rapids, IA in 2006:
http://www.kcrg.com/news/local/3195031.html
Weird Clouds Over Cedar Rapids, Iowa
What did the Iowa weather people say about the clouds? KCRG-TV’9s meteorologist Joe Winters said, “We’ll just call them wave clouds. That’s not actually a type of cloud. It’s just the way they looked. The atmosphere always has waves in it, like the ocean. We just don’t see waves often enough, and today we had the opportunity to do that. And it probably won’t happen again for a long time.”
This type of cloud isn’t that uncommon on the western slopes of the New England plateau in New South Wales, Australia, in winter. It is a kind of stratus probably contorted by mild thermals and contour of the hills.
The picture here appears so dramatic because of the thinness of the cloud layer and the lovely translucent light. I suspect our local aborigine tribes were looking at the same clouds 40,000 years ago, just as the Celts were in Scotland.
Don’t be too hard on the Cloud Appreciation Society. If you have had a hard day at the screen go to the Photo Gallery,start the slide show and feel your blood pressure drop.
It is a slightly English harmless thing,like train spotting and you really need to get away from tall buildings to appreciate the complexity and subtle shape-change of clouds.I am lucky to live in inland Australia where the clouds can be truly spectacular compared with the coast.
The Asperatus clouds look to me like Mammatus with mountain wave turbulence and considering that Mamatus formation is a mystery, perhaps we should have an open mind about Asperatus.
Well, oceanographers have been looking up at certain clouds for some years now and have sometimes commented that, “That looks just like the sea.”
Of course, we aren’t licensed to name clouds so I guess we gotta let that one go. Maybe we will name some sea states “cloudlike.” 🙂
Can I interest anyone in hyper-meteorology?
http://grurgle-the-grey.net/WrdPrss/?p=92
and the two posts after
The first picture reminds me of a phenomenon you often see in the Summer on the West Coast of France adjacent to the lower corner Noirmoutier Island. The clouds move longitudinally to the “stripes”. At the same time a lower level air current brings small feathery clouds across at a right angle. You get a similar perpendicular movements in the waves as the tide comes in.
Asperatus? As in “What asperatus do you use to measure the temperature?
Or “I have invented a new asperatus for humidity control?
(I can see no end of problems with this word and dyslexic kids, or those with speech impediments … )
An asperatus is an apparatus for aspirating your ah tus …
Or is it a person who aspires to us to inspire …
I think the cloud does not need a new name, but if it gets one, it will definitely need a new name…
he lighting has a lot to do with how they look, given the backlight from the low sun. If the sun had been in another position, they would have mostly just looked like plain stratus with a bit of wave shape. The layer is fairly thin.
A group in England dedicated to cloud watching, the Cloud Appreciation Society, became quite excited when viewing numerous photos of the new storm cloud floating in the atmosphere.
The Cloud appreciators describe the cloud as “…a bit like looking at the surface of a choppy sea from below,” said Gavin Pretor-Pinney, founder of the Cloud Appreciation Society, and the first man to identify the new cloud.
Oddly, this bunch needs to get out more. Wave form clouds are well known, common, and ephemeral. They don’t need a new name – they already have one: “wave” clouds. If Pretor-Pinney and the RMS needs a latin name they can call them vacillostratus or vacilloform clouds (or stratovacillus, altovacillus, cirrovacillus or vacillocirrus, which is why they’re usually called “wave” clouds 🙂 .
Keith Minto (00:35:22) :
Don’t be too hard on the Cloud Appreciation Society. If you have had a hard day at the screen go to the Photo Gallery,start the slide show and feel your blood pressure drop.
It is a slightly English harmless thing,like train spotting…
Please, don’t get me started on these “harmless” British fetishes. Thanks to a whacked-out Brit planespotter who couldn’t stay home, I fully expect to get yanked off a plane at any point due to somebody’s no-fly list >:(
“Rectumulus” LOL!
In looking at the various other pictures around of wave clouds, they all have the same characteristic: the layer is thin, allowing sunlight to define the wave density patterns. I think we are not looking at something new, just seeing something common under certain conditions and lighting. My own observations watching a setting sun through different cloud formations leads to seeing structure in cloud decks you can’t see when illuminated from above, or even directly from below.
Nothing to see here, folks!
Trust your goverment, your scientists and the big media journalists. They’re all paid professionals and they know what they’re doing.
Also, have a flu-shot – just in case – watch the news on TV – have some fluoridated water, antidepressants, aspartame, GMO’s and what have you – for they’re all good for you – and they’ve all been approved by Good Science…
Don’t believe me? Well, ask Donald Rumsfeld.
And BTW – stop buying more guns & ammo – instead join the Obama Corps and become a Civil SerfAnt.
And there’s no need for stockpiling food either – just have a food stamp – very low in calories!
With Whole Lotta Love,
BB
Ps. Don’t forget to pay your taxes – Wall Street and The Establishment really needs you and your money…
I want to officially petition for a new “looks like a horsy-stratus” cloud designation.
I can provide peer-reviewed evidence.
This is obviously George Bush’s fault.
SL (15:48:51) :
I can’t believe no one has said this yet! They look like flying sheep to me.
Maybe Harold was successful!
E.M.Smith (02:19:07) :
Asperatus? As in “What asperatus do you use to measure the temperature
No, no! its a politically correct (available in white and coloured varieties) vegetable that makes you smell funny when you pee!
Apparently we’ve succeeded in collapsing the server at the Cloud Appreciation Society.
These wave clouds are apparently nothing more then thin low altitude stratus and nimbostratus forming in a fast moving air mass that happens to be close to terrain, which induces turbulence in what would be a more regular wave pattern, like non-breaking wave patterns in a stream over a rough rocky bottom.
“Altostratus Obamus,” of the idiomatic genus “pie in the sky.”
Digging a little deeper around the web, it would appear that this cloud form is already defined as stratus or altostratus undulatus, undulatus referring to the wavy bottom, and that the cited examples of “asperatus” at CAS are just good examples of the form. You might make a case for some examples being “mammatus undulatus”, depending on their genesis.
At any rate, another word doesn’t seem necessary or desirable, and they are certainly not “new storm clouds”.
Maybe the cloud appreciation society ought to get their tails out of the pub and go out and look at some clouds.
We get these wave clouds all the time over silicon valley; they are so ho-hum.
Partly it is because the south Bay is hemmed in by some hills up to 4000 feet high, and then you get the daily vacuum cleaner winds coming through the golden gate; which play the valley like an organ pipe.
More importantly though, the bottom of those wave clouds are exactly like the bottom of the Arctic sea ice looks. (yeah I know it is crummy grammar).
There’s a picture on the table of contents page of the May 2009 issue of OPN; which is the Optics & Photonic News monthly bulletin. (Page 2)
It’s a USGS/NASA Landsat image looking donw on some mountains somewhere buried in cloud cover, where the whole area is an interfering wave pattern just like that bottom view above, and there is one sharp peak sticking up through the clouds, that is creating a turbulent diffraction pattern around the mountain that stretches down wind for about 15 times the diameter of the peak protruding through the cloud layer, with a whorl pattern that is cellular with cells about the size of the protruding peak.
Much more interesting than those apparatus clouds above.
George
“The unique gray storm cloud was also spotted over Australia, the cornfields of Iowa and high above the Arctic Sea off the coast of Greenland.”
So this particular and unique cloud travels around the world where it is spotted by different cloudspotters at different times? Or is the explanation that the writer has little grasp of the English language?
More cloud pictures
http://news.bbc.co.uk/today/hi/today/newsid_8076000/8076805.stm
I rather like the storkostratus.
[snip]
Reply: While that is not a [snip] site per se, and in fact is an anti [snip] site, in order to prevent discussions of [snip], I’m snipping the anti [snip] so as not to promote a reaction from the [snip] gallery. ~ charles the [snip] moderator.
Another alarmist story about how AGW will cause worse Hurricanes and flooding due to 7 to 23 inch sea level rise in the next 100 years based on the IPCC.
http://www.khou.com/topstories/stories/khou090601_tnt_global-warming-hurricanes.3ab467cf.html
Take a valium before you read it. It’s going to raise your blood pressure.
Why not a post about the “New Age” creed or the “Green Agenda” ? to find out why “they” arrived at such preposterous idea of marketing “Global Warming” and why not another more intelligent and credible theory.
Glenn (18:21:26) :
It’s obvious why the RMS is playing “what figures can you see in the clouds”. From the article:
“Professor Paul Hardaker, the Chief Executive of the Royal Meteorological Society, said: “The process is a long and convoluted one to get through, but we believe there is a good case for this cloud to be added.
“There would probably need to be quite a lot of heat around to produce the energy needed to generate such dramatic cloud formations.
Well the new name suggests itself then:
Nimbyus Nostradamus
Look these “Asperatus Maunder Minimum”:
http://www.giurfa.com/venice.jpg
The undulation pattern in the clouds might be from “gravity waves” (that’s different from “gravitational waves,” mind you). As several commenters have said, it occurs in the lee of mountains. Gravity provides the restoring force, hence the name. If that’s what these are, I recall reading about this effect in clouds 10-15 years ago in Physics Today.
“”” Tim Hamilton (04:45:31) :
The undulation pattern in the clouds might be from “gravity waves” “””
Tim, ordinary deep ocean waves are “gravity” waves; typically wind powered, and as you state, the restoring force on a displaced particle is gravitational, and the wave propagation is non dispersive, so the waves are simple harmonic motion, and all frequency components have the same wave velocity.
In water, you also have another restoring force, that is surface tension; which acts to try and minimise the surface area. But whereas the restoring force in gravity waves is proportional to displacement; (which is the differential equation definition of simple harmonic motion); the surface tension restoring force is absolutely independent of particle displacement, and depends only on the surface tension of water (Newtons per metre).
So surface tension waves are anything but SHM, and the are highly dispersive; so the short wavelength higher frequencies travel faster than the longer wavelenght lower frequencies.
Out in deep ocean waters; the surface tension is totally swamped by the gravity , so deep ocean waves travel non disp[ersively at the same velocity independent of wavelength.
But as the water shallows near shores, and beaches, the power in the gravity waves is reduced while the surface tension remains constant, so the surface tension waves start to dominate, and the higher frequencies run ahead of the lower frequencies, so the wave shape changes from sinusoidal for the SHM gravity waves to a sawtooth waveform, with the water poiling up at the front edge of the wave. Well eventually the high frequencies go right over the cliff, and at a given water depth, depending on the height of the waves, the wave leading edge collapses in the mess that beach bums and surfers travel the world to find.
The atmosphere doesn’t really have anything comparable to surface tension, so we never see those aparatus waves breaking on an upside down beach.
You do need air flow over the lip of the organ pipe (hills) to get the waves started; which is why you don’t see these over the flat midwestern cornfields; and notice that the waveforms are pretty nice symmetrical sinusoids, althoguht they are travelling in several directions and interfering with each other. The interference pattern is going to depend on the ridge line of the hills, and how many indivdual sources it creates; via passes, and peaks.
George
“”” Paul Coppin (08:45:55) :
Digging a little deeper around the web, it would appear that this cloud form is already defined as stratus or altostratus undulatus, undulatus referring to the wavy bottom, and that the cited examples of “asperatus” at CAS are just good examples of the form. You might make a case for some examples being “mammatus undulatus”, depending on their genesis.
At any rate, another word doesn’t seem necessary or desirable, and they are certainly not “new storm clouds”. “””
Paul, I suspect that the only difference between these aparatus clouds, and lenticular clouds, is one of persistence.
With lenticulars, they seem to form right over the generating peak, as a result of being forced up in altitude; till condensation occurs; but they re-evaporate, once the waveform dips lower, thus cutting off the lenticle.
George
George E. Smith–
Thanks a lot for the review of water waves. I knew that they had some real deviations from simple harmonic motion, but I hadn’t heard the reason explained so clearly before. The equations for water wave speed as a function of depth is rather complex. I’ve been trying to assign a student project to design a diffraction grating that would work with water waves, as well as a “lens” that would use a variable water depth to focus the wave. But it’s hard to get a usable effect in the ripple tank without going extremely shallow (~< 1/16"). Next time I try it, I'll have a good explanation of why it works at all, though.
“”” Tim Hamilton (08:52:00) : “””
Tim; One of my Second year Physics Lecturers; who taught the Sound and accoustics part of Physics; had a waves on water fetish.
It didn’t matter what subject he got started on; he could eventually bring it around to waves on water; whcih he loved.
Speaking of diffraction gratings; have you ever considered the idea, that a wave pattern on the surface of the water, is itself an accoustic diffraction grating.
It came to me once, while standing out on the Florida Keys Tarpon flats (on a boat) fly rod in hand, and waiting for a tide change that was calculated to bring the thundering herd of critters right past our stake out spot.
There was an almost imperceptible faint breeze blowing that created a slight wave pattern on the water, which was good for the tarpon to not be so skittish; but not so much wave as to slap against the hull, creating a noise which would blow them off our location.
Yet it wasn’t quiet; my guide commented about the interminable; but faint rushing sound in our ears; with no apparent source. So during a pregnant pause in the action; he asked me what the hell the noise was all about. That gave me an idea that set me bobbing up and down to get my ear as close to the water as possible (flats boats are very low freeboard).
Sure enough; as I changed my ear height, the sound changed its character.
Then I realized that the winds from far away were in fact generating a lot of noise all around us, but it was only audible for the sounds coming from a region close enough to us (but all around us) to be audible.
The somewhat chaotic surface wave pattern was acting as a surface diffraction grating of somewhat undefined but not totally random spacing, that was diffracting the essentially white noise into a frequency spectrum that was distributed roughly in verticaql angle from that apparent audible source radius.
So my up and down bobbing was simply scanning the sound spectrum, and listening to the frequency shift.
Needless to say; my guide (The Scientific American Recipient) was bloody impressed; and of course he made full use of his lecture episode to bamboozle his fellow guides at the bar apres fish. Darn sure we won ourselves a few free drinks at some of those bar meetings.
Yes waves are fun visual things for students; if you can turn just one on with them, it is worth the effort. You can show them interference and diffraction all in a shallow tank with simple apparatus; and hopefully get some surf bums to pay attention more often.
George
PS if you have some apparatus you can use with soap films to demonstrate the surface tension, and its independence of displacement, unlike a balloon skin. Like a couple of parallel wires with one movable end, so you can demonstrate that the work done is simply T x the change in area of the film.
Remember soap films are double sided so it is 2T x delta (a).
My grey matter is a little rusty so I don’t have a mental figure for the order of magnitude of T for modern soap films.
My wife and I saw this same formation over northern Dallas County just a couple of weeks ago. Most unusual — I had never seen clouds like that before.
I just saw this where I live in Crestline, California, 5000 feet above see level. I had never heard of these clouds before and had certainly never seen them. I stood there watching them for a long, long time trying to figure out what they were because they were unidentifiable. Then I took a whole role of film. (:o)) Anyway, I’m glad to know these DO have a name, but now I wish that I understood what caused them to form.