Intersecting cloud ripples

skephu

Senior Member.
This photo was posted a few days ago on the USA TODAY web site:


Legend: "Cloud ripples: Intersecting ripples appear in a cloud layer over the Texas Panhandle last week. The photo was submitted to USA TODAY via Your Take at yourtake.usatoday.com Elizabeth Williams-Cox, Your Take"
In this gallery.

What could have produced those ripples? The photo has been posted in various chemtrail groups and explained as chemtrails/HAARP etc.
 

Mick West

Administrator
Staff member
I think it might actually be some contrails over the top of some ripples. Notice the spacing is nice and even in one direction, but kind of random in the other. Here I've warped the image to make the lines straight:


The date is given as "last week", but it's not at all clear when this was. There's a date in the gallery URL of 2013/04/30, but that does not seems to be specific to any image, and might just be when the gallery started.

Looking at a current last week, the MODIS images show similar things near the Texas Panhandle on Nov 13, 2014
https://earthdata.nasa.gov/labs/wor...p=-105.062256,34.532227,-101.056641,36.900879


More contrast:
 

JRBids

Senior Member.
This photo was posted a few days ago on the USA TODAY web site:


Legend: "Cloud ripples: Intersecting ripples appear in a cloud layer over the Texas Panhandle last week. The photo was submitted to USA TODAY via Your Take at yourtake.usatoday.com Elizabeth Williams-Cox, Your Take"
In this gallery.

What could have produced those ripples? The photo has been posted in various chemtrail groups and explained as chemtrails/HAARP etc.


I don't suppose any of them has explained how they could have been created by chemtrails/HAARP either, though. :)
 

WeedWhacker

Senior Member
The photo has been posted in various chemtrail groups and explained as chemtrails/HAARP etc.

Which is illogical, isn't it? What I mean is, obviously the photo was taken from above that layer of clouds...by a person...in an airplane (presumably). Point is: This effect would likely NOT be visible by the "chem"trail believers, from their positions on the ground.

SO: If there is some nefarious "plot" afoot? The taking of this picture, and freely sharing it, isn't logical.
 

skephu

Senior Member.
The fact that the amplitudes seem to add up at the crossings supports the gravity wave explanation. However, if it's a gravity wave then I don't understand why there are only 2 to 4 waves in the middle of an otherwise flat cloud layer. Usually when one sees gravity waves it's a long series of waves covering a large area, not just a few waves and then nothing.
 

WeedWhacker

Senior Member
The fact that the amplitudes seem to add up at the crossings supports the gravity wave explanation. However, if it's a gravity wave then I don't understand why there are only 2 to 4 waves in the middle of an otherwise flat cloud layer. Usually when one sees gravity waves it's a long series of waves covering a large area, not just a few waves and then nothing.

What is a "gravity wave"?
 

Mick West

Administrator
Staff member
What is a "gravity wave"?

It's a wave, like an ocean wave, or ripples on a pond, that's caused by displacement and gravity.
http://www.atoptics.co.uk/highsky/hgrav.htm
Drop a stone into a pool of water. The spreading ripples are gravity waves. The waves occur between any stable layers of fluids of different density. When the fluid boundary is disturbed, buoyancy forces try to restore the equilibrium. The fluid returns to its original shape, overshoots and oscillations then set in which propagate as waves. Gravity or buoyancy is the restoring force hence the term - gravity waves.

These waves (internal gravity or buoyancy waves) abound in the stable density layering of the upper atmosphere. Their effects are visibly manifest in the curls of the stratosphere’s nacreous clouds, in the moving skein-like and billow patterns of the mesosphere’s noctilucent clouds and in the slowly shifting bands of the thermosphere’s airglow.
Content from External Source
 

WeedWhacker

Senior Member
It's a wave, like an ocean wave, or ripples on a pond, that's caused by displacement and gravity.

Fascinating (to borrow a phrase) because it sounded like a Science Fiction concept, actually.

So in essence, it is the reactions of particles that have mass, within a gravitational field?

(I was going too far into the SciFi aspect, as in...well, I don't know....the "TechnoBabble", as it has been called, in certain SciFi types of shows).
 

Mick West

Administrator
Staff member
So in essence, it is the reactions of particles that have mass, within a gravitational field?

I'm not sure that's the essence, as I've no idea what it means :)

It's more something that happens in a fluid than something you'd define in terms of particles. It's better not to get too technical.

They are termed gravity waves to distinguish them from sound waves. But really you could just say they are just regular waves, kind of like ocean waves.

You can get waves in fluid without gravity, of course. There are sound waves in the Space Station, and a blob of water in zero gravity will have waves, as seen in this example:

Perhaps for clarity it would be best to refer to them as atmospheric gravity waves, or simply atmospheric waves.
 

WeedWhacker

Senior Member
Don't confuse gravity waves with gravitational waves. They are completely different and unrelated concepts.

Perhaps this is where my confusion began.....because AFAIK we still do not have a defined "ToE" or, "Theory of Everything" that has been able to determine the "reason" for gravity...by incorporating and reconciling the many forces that we have learnt of, so far.

We all understand that mass exerts a force, but "How"? That, dear Dr. Watson, is just one of many penultimate questions! :cool:
 

Trailblazer

Moderator
Staff member
"Gravity waves" sounds technical, but it really just means normal everyday waves, as opposed to sound waves, radio waves etc.
 

WeedWhacker

Senior Member
"Gravity waves" sounds technical, but it really just means normal everyday waves, as opposed to sound waves, radio waves etc.

I grasp this, but when it comes to the atmosphere, and "waves" I tend to comprehend differently.

Our atmosphere, our air is a type of 'fluid'...much less dense than water, of course (another commonly known fluid), but also much less visible
(to the naked eye) than water....unless the "flow" of the air illustrates itself through the manifestation of visible moisture, such as a cloud.

The atmosphere as it flows (think "wind") isn't always predictable, and can be influenced in many ways....one is orographically. (Hence, the "Mountain Wave" phenomenon). Which may, or may not be indicated visually to aviators.

I DID notice, in my first link above (about orographic flow of the atmosphere), the term "gravity wave" used in the Wiki article.

SO....this is somewhat analogous to say....a buoy on the ocean, that bobs up and down because of water waves....these water waves are affected by the pull of Earth's gravity. Just as the atmosphere also is affected by gravity. It is still, (I think) as I mentioned earlier....matter (and mass) in a gravitational field. A "side-effect", if you will. The physics of motion; but NOT of the "theory" of gravity, as a whole?
 
I don't have video, but if you watch gravity waves in a mostly clear sky, you will see whisps of cloud disappear on the downwind side and others appear out of clear sky on the upwind side.
 

Jazzy

Closed Account
I spend quite a lot of time on my back staring upward at the sky. One of the perks of age.

It's an Atlantic ocean sky which is cleaved by a 12,000 ft volcano, and it swings an eddy of a fairly prevailing wind from the north west..

I'm on the south-eastern coast, and live mostly under a convective wind from the north east.

The flows cross at various altitudes and clouds can be traveling, on occasion, in three different directions at three different levels.

Not only are there low-frequency gravity waves, but also high-frequency (say 1 Hz), and the sky is wobbling locally, rather like a slow-motion jelly.

This is easier to observe when you are comparing two or three strata at once. And lying on your back.
 

WeedWhacker

Senior Member
I spend quite a lot of time on my back staring upward at the sky. One of the perks of age.

I just spit up my beverage!!! Thanks!!

Oh, BTW..."Look-Up!!" :cool:

(ETA: I have seen the Wiki on so-called "gravity waves" as applied to cloud formations. I remain unconvinced as to the "gravity" aspect, in those descriptions. Sorry, but orographic anomalies are FAR more indicative of the way that air flows, than Earth's Gravity).

Second addition: Has anyone reading this ever been white-water rafting? (It is GREAT fun, I highly recommend it). Water is a fluid, of course....but so is air. Point is....water can create amazing currents....but is (usually) very visible. AIR is not "visible", except where we see condensation of water, as RESULT of the air movements.

(I got tossed out of a raft when we floated into what the "river guide" said was a "fuzzy box of kittens". It was an eddy that spun the entire raft around!! AND, was NOT visible to the naked eye!!!) (I was sitting on the edge of the raft, and not paying attention....which is sort of the point....)
 
Last edited:

Ross Marsden

Senior Member.
I just spit up my beverage!!! Thanks!!
(ETA: I have seen the Wiki on so-called "gravity waves" as applied to cloud formations. I remain unconvinced as to the "gravity" aspect, in those descriptions. Sorry, but orographic anomalies are FAR more indicative of the way that air flows, than Earth's Gravity).

Lee waves are known as "internal gravity waves" because gravity is the restoring force. Inertia leads to equilibrium over shoot, and the resulting buoyancy imbalance (gravity) returns the flow towards equilibrium again, but it overshoots again.

Just like "pilot induced oscillations" could be called "pilot waves", because it is the pilot causing the restoring force (via control surfaces) towards equilibrium, and consequently overshooting. Of course, you haven't done those for a long time. ;-)

ETA: http://en.wikipedia.org/wiki/Lee_wave
 
Last edited:

GregMc

Senior Member.
It rather resembles the intersection of bore waves such as on the Qiantang river http://www.gotohz.com/hzlywywb/whyhangzhou/festivalsandevents/201309/t20130913_88823.shtml http://exclusivepix.photoshelter.com/image/I0000dviFRwAk8vg and common intersecting waves seen on beaches http://www.panoramio.com/photo/96650903 resulting from bending of wave direction around land forms .
Our attention span is so short that the fluid and wave characteristics of the atmosphere tend to remain unnoticed unless viewed with timelapse footage. Here's a good example of the ocean like characteristics of the sky:
 
I think you are referring to mountainous waves, Do
n't? Or a Foehn wind?
They typically are long
I think you are referring to mountain waves, Don? Or a Foehn wind?
They are typically long parallel clouds perpendicular to the wind aloft and form down wind of mountain ranges here in western Montana. I assume they form as air masses oscillate in and out of cloud forming altitudes.
 

Ross Marsden

Senior Member.
Gravity waves can also form more or less spontaneously in a vertically stratified fluid where there is some velocity shear. Such as in the atmosphere there there is a steaper than normal density gradient (cause by changesds in lase rate, even going as far as an isothermal or inversion layer) where there is also changes in wind speed or direction.

We see this turning up as ripples on a sandy sea bottom, and ordinary ocean waves (where there is a really rapid density change at the surface).

These waves are often made visible when there are clouds involved as well - all the undulatus and billow types.
 
Top