Black and White Contrail - Above or Below

Mick West

Administrator
Staff member

A contrail and a cloud layer. It looks like it was above it casting a shadow, and then changed to below it. I'm not entirely sure. Kind of odd as you'd think it would be climbing. So is then shaded by the cloud layer, and then brightly lit above it?
1:39PM PST, 21:39UTC,
Plane is flying from bottom right to top left, i.e east, away from the sun.
 
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I took video I'll upload it shortly, but it showed my identification was incorrect. It's a Q400 prop tip contrail at 25,000 feet. Even better!!

20161212-140636-nq62u.jpg

20161212-141130-jnbix.jpg

Alaska 2586
 
Any chance the dark part is a distrail?

There's a middle bit between the dark and light that seems to be a distrail, but I think the dark part is actually just the contrail below the cloud layer, so essentially in shadow.
20161212-142300-orueo.jpg

20161212-142417-yzt9f.jpg
 
I think that all of the contrail is probably below the cloud layer. The cloud layer creates an uneven background, both in optical density and illumination terms. To the observer, it is appears denser closer to the horizon because of the viewing angle, and it is much brighter around the sun because of Mie scattering being predominantly in the forward direction. Against denser and brighter background, the contrail appears darker, but against less dense and opaque background higher in the sky, the contrail looks brighter.
 
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I think that all of the contrail is probably below the cloud layer. The cloud layer creates an uneven background, both in optical density and illumination terms. To the observer, it is appears denser closer to the horizon because of the viewing angle, and it is much brighter around the sun because of Mie scattering being predominantly in the forward direction. Against denser and brighter background, the contrail appears darker, but against less dense and opaque background higher in the sky, the contrail looks brighter.

Possible, it seems like a more abrupt transition than I would expect though. But also there does not really seem to be any disruption of the cloud in the suggested "distrail" part.
 
Panorama showing more of the trail at once.
Pano_IMG_1783=aw.jpg
This has beenadjusted to bring out more detail and resized to 1920 wide. The full sized unadjusted pano is attached as a .ZIP
 

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