1. Trailblazer

    Trailblazer Moderator Staff Member

    I was just doing a bit of skywatching out of the train window when a dark trail caught my eye. At first I thought it must be a contrail shadow but there was no obvious source, and the sun angle seemed wrong. Then I noticed that it lined up with what looked to be a distrail in a cloud overhead.

    Here's a series of photos.

    IMG_2563.JPG
    IMG_2565.JPG
    IMG_2566.JPG
    IMG_2568.JPG

    You can see that it also seems to line up with a distrail in a cloud in the distance.

    Any ideas what's going on? There seems to be some thin hazy high cloud with a few faint ripples visible in it, so is it possible the distrail is continuing through the haze? That seems unlikely as the thin cloud is presumably much higher than the (stratocumulus?) cloud where the distrail appears overhead.

    The dark trail was only visible briefly so it seems to be dependent on sun angle, disappearing as the train moved on.


    Photos were taken 8.00-8.01pm this evening as the train was near Byfleet and New Haw station in Surrey, looking roughly west. Planes are landing at Heathrow in that direction and taking off to the east today.
     
    Last edited: Jun 6, 2018
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  2. Trailblazer

    Trailblazer Moderator Staff Member

    Contrast enhanced to show how the dark trail joins up with the distrails at either end.

    IMG_2563.JPG
     
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  3. Mick West

    Mick West Administrator Staff Member

    Interesting. Looking at the middle section of the trail I'd have said it was a lower contrail that's in shadow.
    Here's an even more enhanced version.
    Metabunk 2018-06-06 13-07-11.
    (Mostly using Photoshop's "dehaze" in Camera Raw Filter)

    The sun looks too high to be casing a shadow on the trail though. This section looks like if it was a trail, then it's lit on the wrong side, suggesting it is actually a distrail.
    Metabunk 2018-06-06 13-12-13.
     
  4. Clouds Givemethewillies

    Clouds Givemethewillies Active Member

    Last edited: Jun 6, 2018
  5. Trailblazer

    Trailblazer Moderator Staff Member

    It's not so easy to see in the photos but the end closest to the camera was definitely a distrail through the cloud, with deformed "ragged" edges, not a darker trail in front obscuring the view.
     
  6. Clouds Givemethewillies

    Clouds Givemethewillies Active Member

  7. Trailblazer

    Trailblazer Moderator Staff Member

    I don't think the timings work. Also when I see distrails like the one in the foreground and in the distance they are usually planes landing at Heathrow, so fairly low, like 6-8,000ft.

    I was thinking AF1080, with the Ryanair flight FR9306 (circled, at 37,000ft) being the bright contrail crossing the distrail from right to left.

    upload_2018-6-8_12-22-43.

    The curving trail to the right seems to match up pretty well with the sun direction for 8pm BST that day:

    upload_2018-6-8_12-32-6.


    It was at about 11-12,000ft as it passed over the photo location, at 7.54pm:

    upload_2018-6-8_12-34-43.

    And by the time I took the photo it had turned to the right and descended to about 2,000ft. Planefinder doesn't match the track to the plotted position very well though:

    upload_2018-6-8_12-37-37.



    FR24 reckons it was more like 7,500ft over Byfleet:

    upload_2018-6-8_12-40-39.

    upload_2018-6-8_12-41-40.


    It would be interesting to see a 3D view of that flight path, from the location of the train, to see if it matches up, if anyone has some time to kill.

    The train location can be found pretty accurately from the pylons - this is the tall one, with the rest of the electricity station to the left.

    upload_2018-6-8_12-45-56.
     
    Last edited: Jun 8, 2018
  8. Clouds Givemethewillies

    Clouds Givemethewillies Active Member

    Your plane is mighty low, although cloud did form at the top of the boundary layer at Chilbolton later on. I was assuming that your times were BST and FR24 were UTC. I had altitude filters set around the height of the shown cirrus cloud, but FR24 does not seem to like me, for archived data. There were some small patches of cirrus at ~11km. just below the tropopause here after dark that night, but otherwise completely clear.
    https://uk.flightaware.com/live/flight/TCX1V/history/20180606/1819Z/EGGD/LGRP
     

    Attached Files:

    Last edited: Jun 8, 2018
  9. Clouds Givemethewillies

    Clouds Givemethewillies Active Member

    You are one of the few people in The World(tm) that can work that magic without going mad. Get on with it!
     
  10. Trailblazer

    Trailblazer Moderator Staff Member

    Some of us have jobs! ;)

    Just looking at it by eye from the train (which I appreciate is not an accurate guide to altitude) the clouds with the distrails appeared fairly low. The parallax between the photos, as the train travelled westwards, appears to indicate that the dark trail was also significantly below the contrail remnants which are presumably up there in the cirrus layer, as there is significant motion between the two:

    upload_2018-6-8_15-21-21.


    upload_2018-6-8_15-22-5.
     
  11. Clouds Givemethewillies

    Clouds Givemethewillies Active Member

    Attached Files:

  12. Clouds Givemethewillies

    Clouds Givemethewillies Active Member

    If it is AFR1080 then the white haze could be the aerosol at the top of the boundary layer, that you can sometimes see swelling with increased RH, as it approaches cloud formation. At these altitudes the plane would not add much water/relative humidity. The heat produced by the plane might be a bigger effect. Capture.PNG
     
    Last edited: Jun 8, 2018
  13. Trailblazer

    Trailblazer Moderator Staff Member

    This one is definitely a distrail, similar direction, taken from the back garden a few minutes ago.

    IMG_2620.JPG
     
  14. Clouds Givemethewillies

    Clouds Givemethewillies Active Member

    Last edited: Jun 11, 2018
  15. Trailblazer

    Trailblazer Moderator Staff Member

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  16. Clouds Givemethewillies

    Clouds Givemethewillies Active Member

    Probably the warm type. It looks like the temperature is only just below freezing there.