APOD: Exceptional Rocket Waves Destroy Sun Dog (2010 Feb 23)

[The Code]

Under high enough pressure gas changes state, and becomes a liquid. But that is not happening here

I do not agree. Sorry

(the pressures are nowhere near high enough).

The Earths atmospheric Globe is like a liquid. The higher you go, the more freely moving liquid. Snag is. The higher you go the lower the pressure. High pressure sonic boom in the low pressure upper atmosphere . Your going to see it, like a stone in the pond. With condensed water crystals and all. Rippled Vapor trail.

[bystander]

I think you are confusing liquid, a phase of matter (gas, liquid, solid), with fluid, which is more of a property of all gases, but only some liquids. Most definitely, the atmosphere is not liquid. Although there may be some aerosols present, it is gaseous.

[Chris Peterson]

The Earths atmospheric Globe is like a liquid.

It isn't a liquid, and it doesn't behave like one.

High pressure sonic boom in the low pressure upper atmosphere . Your going to see it, like a stone in the pond. With condensed water crystals and all. Rippled Vapor trail.

Yes, you may. Your original observation presented a possible explanation for what we see in these videos. But it has nothing to do with the atmosphere either being a liquid or acting like one. It's simply a question of the index of refraction changing with density. That's why the stars twinkle, and it's why we can sometimes see shock waves in the atmosphere.

[The Code]

The Earths atmospheric Globe is like a liquid.

It isn't a liquid, and it doesn't behave like one.

High pressure sonic boom in the low pressure upper atmosphere . Your going to see it, like a stone in the pond. With condensed water crystals and all. Rippled Vapor trail.

Yes, you may. Your original observation presented a possible explanation for what we see in these videos. But it has nothing to do with the atmosphere either being a liquid or acting like one. It's simply a question of the index of refraction changing with density. That's why the stars twinkle, and it's why we can sometimes see shock waves in the atmosphere.

So I was maybe right the first time.

I could not see any other way. other than, Water vapor .

Thanks Chris

[MacRoos]

To create the visible waves in the cloud when the rocket passed, is in my mind due to the presence of a very thin layer of ice crystals through which the rocket passed.

To create a halo and sundogs, the ice crystal faces in the cloud must be (somewhat) aligned, otherwise the random orientations would look just be a "regular" cloud, with no halos and sundogs. Such alignment of crystals could only happen in relatively undisturbed air, otherwise the crystals would be mixed up into random orientations, and the sundog would disappear. Therefore, if you disturb the air, as you would with a passing rocket, the waves in the air in which the crystals are suspended, would change the alignment of the crystals, as seen in the pattern.

For such a disturbance to be visible, the layer of crystal must be very thin. This can be seen by the shadow of the rocket visible in the video - it can only appear that way if the cloud "canvas" on which the shadow is "painted" is thin. If the cloud/crystal layer was thick, it would not cast such a distinct shadow.

As the layer is thin, it is possible to see the "waves" in the layer. These disturbances happen in all rocket flight, but the presence of such a thin cloud of ice crystals must be quite rare - therefore not seen often.

Therefore the pattern was created by a thin layer of ice crystals, undisturbed air, through which a wave-creating vehicle passed. Fantastic.

[DavidLeodis]

I am wondering if there was a matching sundog to the left and, if so, what happened to that

[Lucra]

By the time the sound waves should reach the left sundog (if there was one) they must have been heavely weakened. In such a way that the effect became most probably unvisible. At 10km high, an apparent distance of 44° between left and right sundog stands for about 8 km.
My geuss,
Luc

[Arie Melamed-Katz]

I am wondering if there was a matching sundog to the left and, if so, what happened to that

The sundog in the picture is the left one since the red color is always closest to the sun.

[Arie Melamed-Katz]

I wrote a bit about this rare and wonderful event in my Hebrew blog. Here are my thoughts:
The waves appear instantly through the whole cirrus cloud. It indicates that they were produced earlier in some continuous process and hit the cloud at the same time. A rough estimate of their speed indicates that they move with the speed of sound and the wavelength is a few tens of meters. In other words the frequency is indeed in the infrasound region. Assuming that their origin is in the engine, it can be interesting to figure out why the engine produced such vibrations?

The waves appear together with the Prandtl–Glauert condensation, which usually appears just before the rocket becomes supersonic.I don't think that we see a shockwave since the waves were generated before the rocket produced the supersonic shockwave. Since the speed of the rocket is transsonic at this stage the waves and the rocket get to the cloud approximately together.

Watching carefully, the waves can be seen also in NASA's Launch replay immediately after the rocket emerges above the cloud and it's shadow is seen. Besides the shadow a black fume is seen in this video. I wonder if it indicates some sort malfunction?

Regarding the sundog: it was probably destroyed by these long sound waves that changed the position and orientation of the ice crystals. After a few seconds the sundog appears again.

[neufer]

Regarding the sundog: it was probably destroyed by these long sound waves that changed the position and orientation of the ice crystals. After a few seconds the sundog appears again.

So "a few seconds" is the relaxation time for cirrus ice crystals to come back to equilibrium orientation after a turbulent disruption.

It is hard for me to believe that the ice crystals could respond coherently to infrasound with periods much shorter than a few seconds but I suppose that it is not impossible.

[DavidLeodis]

I am wondering if there was a matching sundog to the left and, if so, what happened to that

The sundog in the picture is the left one since the red color is always closest to the sun.

Thanks Arie. For some reason I assumed the rocket was rising between sundogs and that we only saw the one on the right (as we see it) with the other being offview to the left. I should have realised that if the rocket was where I thought then the Sun would have looked to have been where the rocket was when it was level with the sundog yet the Sun is not directly visible in the photo.

[Little_SDO]

ULA's response in regards to the SDO's shock waves:

The final thought back here is that the effect we saw was due either to shockwaves from the vehicle as it went supersonic (approximately 82 seconds into flight), or varying densities or shockwaves in the engine plume. One of these phenomena could have interacted with moisture in the atmosphere to produce the effect.

A Japanese TV station reported on it yesterday, also discussing the engine plume as the source.

http://doga.nhk.or.jp/doga/viewvideo.js ... 298219.flv

[Arie Melamed-Katz]

ULA's response in regards to the SDO's shock waves:

The final thought back here is that the effect we saw was due either to shockwaves from the vehicle as it went supersonic (approximately 82 seconds into flight), or varying densities or shockwaves in the engine plume. One of these phenomena could have interacted with moisture in the atmosphere to produce the effect.

A Japanese TV station reported on it yesterday, also discussing the engine plume as the source.

http://doga.nhk.or.jp/doga/viewvideo.js ... 298219.flv

The waves appear before the vehicle goes supersonic. The engine plume or the engine itself sounds to me as a more reasonable cause.

[ems57fcva]

The waves appear before the vehicle goes supersonic. The engine plume or the engine itself sounds to me as a more reasonable cause.

I concur with this explanation. As I mentioned above, you can hear the engine sound go from being fairly consistent to being more like a "boom-boom-boom". I would guess that this comes from the plume instead of the engine. Or at least I hope that it is the plume. since if the cause is in the engine itself that could indicate a potentially dangerous instability.

[bystander]

The waves are probably a manifestation of a Prandtl–Glauert singularity as are Prandtl–Glauert condensation clouds. The so-called singularity occurs at transonic speeds, just before going supersonic, just like in the video.

[Francisco Elias Duran]

The missile may have caused fluctiación between atoms in the atmosphere by the pressure beneath him.