Contrail shadow?

[GM4AJK]

Here's an interesting one: a contrail with a shadow that reaches the ground. Is that a thing? (I've never seen such):-

 

[Mendel]

Iain Cameron seems to imply he saw the black line before he took the picture, which would rule out a camera artifact?

With the exact time, we could identify the aircraft and the position of the sun. If the geometry matches the direction of the shadow, I'd conclude that's what it is, though it seems highly unusual to see a shadow in air.

 

[GM4AJK]

With the exact time, we could identify the aircraft

I've asked in the X thread for the date/time. I also suggested that if we identify the plane there's a chance we can get the flight crew to see the image, I believe a few are often happy to see images of their planes, especially doing something rare,

 

[JMartJr]

Is it even possible for the shadow to be that distinct yet that much narrower than the obect casting it?

Also, it looks like the shadow in the sky is not perfectly aligned with the contrail but slightly to camera left... in that case, shouldn't any shadow on the ground be well off to camera right?

 

[Mendel]

Is it even possible for the shadow to be that distinct yet that much narrower than the obect casting it?

Also, it looks like the shadow in the sky is not perfectly aligned with the contrail but slightly to camera left... in that case, shouldn't any shadow on the ground be well off to camera right?

Thank you for bringing the shadow on the ground to my attention.

If the contrail is 80m wide, the umbra would reach the ground from FL210.
The camera needs to approximately be in the plane of the umbra, i.e. it must be looking along the shadow to see almost only shadow in some directions. And it was.

I don't see any problems with the geometry here.

Note that shadow line is deep blue, not black. We're seeing the sky ahead of and above the shadow. The shadowed area is simply not blue, while the air around it is.

 

[Eburacum]

Some contrail shadows to compare it with, from the Atmospheric Optics website.
https://atoptics.co.uk/blog/contrail-shadows/

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I note that these shadows very often appear to be close to the contrail itself, probably because they are easiest to see when looking directly through the shadow towards the contrail. Contrail shadows are shadows formed in atmospheric haze; if you are directly underneath the contrail the shadowed area is much clearer.

 

[JMartJr]

I may be confused... when they say "reaches the ground," I read that as meaning it was casting a shadow on the ground, and assumed they were referring to the thin dark line across the ground running more or less where/how a shadow of the contrail cast onto the ground would run, other than appearing to be very narrow.

 

[MonkeeSage]

Similar shadows discussed in this thread: https://www.metabunk.org/threads/da...kent-—-contrail-volumetric-edge-shadow.12958/

 

[Eburacum]

I doubt that the shadow on the ground is related to the shadow in the air, although it may be. Shadows form in the atmospheric haze quite readily; I saw a haze shadow from the window of a plane recently, although the shadow didn't reach the ground.

 

[Ann K]

Similar shadows discussed in this thread: https://www.metabunk.org/threads/dark-vertical-lines-in-folkestone-kent-—-contrail-volumetric-edge-shadow.12958/

Quote from @Mick West 's OP on that thread:

The straight line of the shadow is not the exact shadow the contrail, but rather a "ray" of shadow viewed edge on.

In other words, it isn't a shadow on an object; it's a "slice" of shadow, a plane of shadow through a somewhat hazy atmosphere. And while they are probably not rare, its unusual for the viewer to be in just the right place to see it edge-on like that.

 

[Trailblazer]

With the exact time, we could identify the aircraft and the position of the sun. If the geometry matches the direction of the shadow, I'd conclude that's what it is, though it seems highly unusual to see a shadow in air.

He posted a reply saying it was 11.22am on Feb 14th.

That matches this Air France flight:

View from the summit, looking northwards:

And turning round to the other direction you can see that the path of the plane was close to the sun.

To get the shadow "beam" effect the contrail has to be exactly crossing the sun from your viewpoint, so the trail must have been blown slightly eastwards by the wind in the four minutes or so between the plane passing the sun (at 11:18am) and the photo being taken:

For comparison here is a photo I took back in 2017 of a similar effect:

I couldn't fit it all in shot, but panning left you can see that the trail passes right over the sun: