posted 03-20-2002 05:02 AM            

at 600 mm

at 140 mm

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posted 03-20-2002 08:42 AM            

It would appear to be a contrail. Not close enough of the aircraft to refute the claims of spraying. The trail looks like a typical contrail though.

The uneveness is a good visual example of intermittent air turbulence. The well defined inner thin part of the trail is a great example of the wingtip vortices. Not sure if your lens was good enough to see it but they spin very rapidly. Why one vortice? Don't know, it might be from the bumps. Sometimes you see two, one or none in a contrail. I cruised 1000 feet below the exact type of trail before and have gotten a great look at scenes like this before.

Hitting one of these can be unpleasant.

If its your home location and the time stamp is accurate Quakker, my guess is that it is a widebody 747/777/MD11 type heading east thru southeast consistent with schedule flights from Asia to the US.

posted 03-21-2002 01:24 AM            

Pluto — I take that to mean you’re referring to the magnification I was using and not the actual quality of the camera or lenses themselves. My camera is a Minolta STsi Maxxum. The lens combo I use for my long-range shots is a Quantaray 70-300mm 1:4-5.6, coupled with a Quantaray 2X tele-converter. The camera’s internal clock is calibrated with WWV and I check it at least once a month. It keeps pretty good time, actually.

How does a wing-tip vortex remain so tightly wound and stay that visible so far behind the aircraft? How does a vortex become part of a contrail and continue so neatly within its confines? In the image below, the smoke trails from the wing tips of this 747 are taking very different trajectories from those being directed more in a downward path by engine exhaust.

In fact, at cruising velocity, the tips of an airliner’s wings are lifted significantly higher, with respect to where its engines are cutting through the sky. This is especially true for the two-engine variety. I have a series of photos in my collection that clearly show this.

http://www.dfrc.nasa.gov/gallery/photo/B-747/Small/ECN-4242.jpg

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posted 03-21-2002 05:27 AM            

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posted 03-22-2002 03:13 AM            

it appears to me that the contrail drifted into the aircraft's wake. The vortice in the trail isn't a result of an actual wing tip vortice condensation, nor the result of the contrail. Rather, the tip vortices spin for many minutes after an aircraft passes, and often without the visually seen condensation. this is called the 'wake'. Wake turbulence is also affected by the wind and can shift and sink, but at a different rate than the contrail. When the vortice reacts with the contrail (which is also moving) it creates a visually noticeable vortice trail. The reason why there's only one is most likely due to the fact that the other vortice is outside the contrail.

It's actually very common to see entire contrails wrapping around itself due to the aircraft's wake. I've seen very good photos of jets flying through the tops of clouds, and they form very neat looking swirls behind it from the wake vortices.

Then I had two questions after that:

If the wake and the contrail are moving at different rates, relative to each other, then would not the visible vortex be seen to traverse the contrail rather than tightly hug one edge? Also, doesn’t the spinning vortex tend to expand, increase in diameter, as it ages...???

What about all this...??? What do others see as the consequences of when wake meets contrail...???

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posted 03-23-2002 02:38 AM            

I know where the photo originates and it was a topic here a year or so ago...sky chromosomes...I believe....

I don't see a conspiracy revolving around this photo, but I have seen these before and they don't have the attribute of commercial air traffic associated with them...nor do they form in even the most liberal of RH measuring statistics (ADDS)...(my observation)...

considering this particular trail has never been delt with seriously by chemsters or debunking entities...to my knowledge...

I find it interesting...

btw, did you see the talking cat ?

Talking Cat

posted 03-24-2002 03:49 PM            

maybe you could sweet talk Thermit into giving you this picture below as a avatar

posted 03-26-2002 04:50 AM            

From E. Coli:

The spotty nature of the contrail leads me to beleive that the humidity is only marginally high enough to sustain a weak contrail, and as for the shape, they are consistent with what it looks like when a contrail has inter-mingled with the aircraft's wing tip vortices.

The trail was healthy enough to spread and “gently” obscure a large portion of the sky within 45 minutes. In fact, the lower left portion of the 140 mm shot shows the edge of another “weak” trail that had been laid down a little more than an hour before that photo was taken.

Continued from the same thread referenced above... PacerLJ35:

To your questions....yes, it would move, and yes, it would expand. But since we only have still photos, we can't see the progression of the vortice in real-time. There is also nothing to provide scale...vortices will expand, but contrails often expand as well. Often a contrail (in saturated air masses) will expand to proportions much larger than the aircraft itself. The wingtip vortices will expand as well, but not near the size of the contrail. Also, since the visible vapor used to spot the vortex is made of contrail-created vapor, it will tend to not dissapate along with the vortex itself.

Then I added:

“But since we only have still photos, we can't see the progression of the vortice in real-time. There is also nothing to provide scale...”

Not necessarily true. For all intents and purposes, it is safe to assume that the aircraft’s velocity was a constant in the volume of sky that appears in the photographs. What we see in the 140 mm frame is essentially the history of that trail, for what I estimate to have been around 30 to 40 seconds. The scale can be roughly determined just by knowing the angular field of view provided with a 140 mm lens. (Any professional photographers out there who know this off the top of their heads?) The aircraft was receding in a southeasterly direction, with the camera pointed SSE at an elevation angle of 40°. This is not Swiss watch surgery.

“Also, since the visible vapor used to spot the vortex is made of contrail-created vapor, it will tend to not dissapate along with the vortex itself.”

I don’t see how this would have to be so, either. For one thing, NASA-santioned contrail physics state that whatever trail is visible must be in the form of ice crystals, given the temperatures required for contrail formation. One does not “see” vapor. By strict definition, all clouds are composed of either water droplets or ice crystals.

Especially with less than one third atmosphere of pressure at cruising altitudes, any wing-tip induced vortex is going to have a much shorter lifespan than one which is generated near sea level. As the vortex, itself, dissipates, so will any visibly compressed collection of condensed material. There would be nothing to hold it together in that string-like form. It would be rapidly absorbed by the surrounding contrail and take on the local density in that sample...

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posted 03-29-2002 01:02 AM            

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posted 04-11-2002 05:22 AM            

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posted 04-12-2002 11:52 PM            

Ok, wisequakker has challenged me to explain what he has photographed: www.chemtrailcentral.com/...01124.html

The wake of an aircraft is initially composed of a parallel pair of counter-rotating vortices formed at the wing tips. Over time, these vortices come under the influence of a sinusoidal mutual inductance instability (Crow), which causes them to touch each other, eventually reconnecting to form vortex rings which oscillate.
Between each ring, ice crystals caught between the oscillations form smaller snake-like vortices which are seen in your photos.

Don't believe me? Argue it with these guys at Cornell:
http://www.vortex.mae.cornell.edu/long_top.html

Sounds like a plan to me. I visited the Cornell site, saw the same type of thing based on a series of photographs in their simulation, and managed to stumble through the accompanying text.

Admittedly it is kind of complex, and fluid dynamics was not my strong suit (nor were the diffie-q's you need to pencil-whip them). Nonetheless, I'm convinced that the 'rings-on-a-snake' are explained jsut fine by interaction of vortices.