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  1. Trailblazer

    Trailblazer Moderator Staff Member

    I have no doubt that was the right plane.

    I have a clear view to the west from my bedroom window. I can watch planes that fly nearly overhead as they head west towards America and can often see still see their contrails with the naked eye when they are over Wales, 100 miles or more away – even when the contrails are relatively short.

    See for instance this post in this thread. The plane passed only a few miles to my north so I was able to watch it all the way and ensure it was the same plane. That photo was taken when it was 125 miles away.

    It's easier close to sunset as the trails shine out against the surrounding sky.

    1946.PNG
     
    Last edited: Oct 9, 2016
  2. Clouds Givemethewillies

    Clouds Givemethewillies Active Member

    DSCF3514.JPG DSCF3510.JPG green flash dolphin.
     
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  3. Trailspotter

    Trailspotter Senior Member

    How far is the lowest contrail? Check this thread, you may got a record ;)
     
  4. Trailblazer

    Trailblazer Moderator Staff Member

    Maybe this one?

    upload_2016-11-29_18-6-11.

    upload_2016-11-29_18-10-30.



    About 170 miles if so.

    upload_2016-11-29_18-9-10.
     
  5. Mick West

    Mick West Administrator Staff Member

    I think it's probably the closer one, in the middle. 170 miles would put a contrail very close to the horizon. The 120 mile contrails I see are seem practically level with me.

    It's also more at right angles to your view line, which matches the flat angle.
     
  6. Clouds Givemethewillies

    Clouds Givemethewillies Active Member

    I agree that it does not seem low enough... however the track is close to parallel
    to the horizon, which means that the track is perpendicular to the line between Aberystwyth and somewhere near Cardigan, which is at the end of the headland you can see near the sun. EIN594H should be dropping relative to the horizo n. (as far as I can tell by eyeballing FR24..) Bonus points for anyone who spotted the dolphin and a (very weak) green flash in no. 3.
     
  7. Trailblazer

    Trailblazer Moderator Staff Member

    Probably right. I did think it was a bit far. That would be almost exactly 100 miles from Aberystwyth if it was the nearer one.

    I see the flash.... and a couple of gulls, but no dolphin!
     
  8. Clouds Givemethewillies

    Clouds Givemethewillies Active Member

    A little later to give a better idea of scale. DSCF3543.JPG
     
  9. Mick West

    Mick West Administrator Staff Member

    Red is Aer Lingus (the closer flight). Over the sun and flat at :07

    20161129-110350-umibu.
     

    Attached Files:

  10. Clouds Givemethewillies

    Clouds Givemethewillies Active Member

    I'll try for the record tomorrow if it stays like this. :)
    [​IMG]
     
  11. Clouds Givemethewillies

    Clouds Givemethewillies Active Member

    I think we have a new record for contrail distance! One of these three. DSCF3688.JPG afr010.PNG
     
    Last edited: Nov 30, 2016
  12. Trailspotter

    Trailspotter Senior Member

    What is the heading from your location to the tip of visible land on the left?

    Edit:
    From your photo of the setting sun today in another thread, it is about 233°
    [​IMG]
     
    Last edited: Nov 30, 2016
  13. Clouds Givemethewillies

    Clouds Givemethewillies Active Member

    I would say 233 degrees true, but I am not very good with Google Earth, and I am not sure how much is below the sea, but Cardigan Island would be about right. I saw a few planes around there, but waited until I got one in line.
     
  14. Trailspotter

    Trailspotter Senior Member

    This would make UAE205 the most likely candidate with an estimated distance to the plane of about 230 miles. Will measure on Google Earth later, when the flight is completed.
     
  15. Clouds Givemethewillies

    Clouds Givemethewillies Active Member

    uae205 distant.PNG This screen capture file has a time of 4:33 (UTC)
     
  16. Trailspotter

    Trailspotter Senior Member

    UAE205 has not arrived to New York yet, but I've looked into the flight track log. At the time of the photo (Wed 04:30:49 PM GMT), the plane's coordinates were 50.2777 -8.3817. This is at the right heading from you location and at the distance of about 236 miles (205 NM):
    Screen Shot 2016-11-30 at 21.05.08.

    When KML file of the track is available, it can be viewed on Google Earth from your location and compared with the photo directly.
     
    Last edited: Nov 30, 2016
  17. Clouds Givemethewillies

    Clouds Givemethewillies Active Member

    Some of the reporting facilities might be a bit biased..

    I should have hung on until it reached 250 miles..
     
  18. Mick West

    Mick West Administrator Staff Member

    You can get the google earth file before a plane has landed, just add /google_earth to the full URL of the flight in Flightaware.

    eg:
    https://flightaware.com/live/flight/UAE205/history/20161130/1440Z/LIMC/KJFK
    https://flightaware.com/live/flight/UAE205/history/20161130/1440Z/LIMC/KJFK/google_earth
     

    Attached Files:

    • Informative Informative x 2
  19. Trailblazer

    Trailblazer Moderator Staff Member

    Are the more distant (and further west) headlands over the horizon from your viewpoint, CGMTW?
     
  20. Clouds Givemethewillies

    Clouds Givemethewillies Active Member

  21. Clouds Givemethewillies

    Clouds Givemethewillies Active Member

    Yes, I posted some photos from higher up once, but I could still not see Strumble Head.

    Edit:https://www.metabunk.org/attachments/dscf2819-1-jpg.21547/

    Whats a 'CGMTW'?
     
    Last edited: Nov 30, 2016
  22. Trailspotter

    Trailspotter Senior Member

    I have added your photo to Google Earth, assuming the horizontal FOV is about 2°. This gives a good match for the land, but the contrail is higher than the track. The discrepancy probably is due to refraction.
    UAE205 contrail.

    The sun position at 4:05 PM GMT and the plane position at 4:31PM match the geography quite well.

    What is the actual FOV of your photo? If it and the photo of the setting sun are at the same focal length, it is probably a bit more than 2° (4.7 diameters of the Sun):
    farthest contrail.
     
    Last edited: Nov 30, 2016
  23. Mick West

    Mick West Administrator Staff Member

    You need to "add photo", then you can zoom in. For the photo link you can use https://www.metabunk.org/t (which will let you share the viewpoint more easily, it's just a fully transparent PNG), then adjust FOV, tilt and heading

    20161130-150959-qr5e5.
     
  24. Clouds Givemethewillies

    Clouds Givemethewillies Active Member

    Amazing forensic trail mapping skills, orders of magnitude better than CTers.

    I will try to get information about the camera later today.

    Remember that the KML file shows barometric alitude 36,00ft.= 11km. = 226.00Hpa - https://en.wikipedia.org/wiki/International_Standard_Atmosphere
    so it was actually flying at 226Hpa which was about 11159 km.
    http://weather.uwyo.edu/cgi-bin/sou...AR=2016&MONTH=12&FROM=0100&TO=0100&STNM=03808
    It only accounts for a small error in this case, but should be bourne in mind.
     
  25. Trailblazer

    Trailblazer Moderator Staff Member

    Is this also a contrail, but unlit? It looks like it, but I can't really see how it can be, because if it appears lower, and therefore more distant, so therefore it ought to be more sunlit.

    upload_2016-12-1_10-38-28.
     
  26. Clouds Givemethewillies

    Clouds Givemethewillies Active Member

    I did notice it, but as you say it should be lit, if a contrail. I guess it is the aerosols at the top of the (low) boundary layer swelling with higher humidity levels there. - cloud formed later.
    Unfortunately this is broken at the time, but you can see the low aerosol/boundary layer.
    [​IMG]
     
  27. Clouds Givemethewillies

    Clouds Givemethewillies Active Member

    Here are some more photos from around that time, for hard-line Google Earthers. + sun today at 100x zoom through welding glass, for camera calibration. DSCF3675.JPG DSCF3676.JPG
     

    Attached Files:

    Last edited: Dec 1, 2016
  28. Clouds Givemethewillies

    Clouds Givemethewillies Active Member

    This is what it says for the 'record' photo (3688). I know this other photo of a plane(3642) was 100X, as usual for plane photos. The 'record' photo might be 50x optical, and the plane 50x optical, 2x digital, although the resolution/file size should be different, in that case. The sunset photo is dsc3651
    3688.PNG
     

    Attached Files:

    Last edited: Dec 1, 2016
  29. Trailspotter

    Trailspotter Senior Member

    The full zoom focal length of your camera (215 mm) corresponds to 1200 mm in 35 mm equivalent. It gives the horizontal FOV of 1.72°, 2x digital would half it to 0.86°.

    The sunset photo's focal length 139 mm corresponds to 776 mm, or the horizontal FOV of 2.66°. It is about right (~5 Sun angular diameters).

    It was possible to fit your photo for both FOV of 1.72° and 0.86° as the wedge-shaped piece of visible land scales well. In both fits, the trail remained above the track. They come together only at the horizontal FOV of about 0.40° (4x digital zoom). At these tiny angles the fitting results strongly depend on the exact location of the camera, particularly, its altitude above the ground/sea level.
     
  30. Clouds Givemethewillies

    Clouds Givemethewillies Active Member

    I normally use 51 metres for SHCC when it was down at ground level. The photo might have been a couple of metres lower. The plane refraction should be about the same as for the sun as both paths go through most of the atmosphere., but it should be less for the horizon as the path is much shorter, IMO.

    edit ps. I have not been able to digitally zoom more than 2x with the camera. I use 'P' mode to even get that choice.

    50x optical 2x digital https://www.metabunk.org/attachments/dscf3695-1-jpg.23179/
     
    Last edited: Dec 1, 2016
  31. Trailspotter

    Trailspotter Senior Member

    At the eye altitude of 49 m above sea level and horizontal FOV of 0.86°, the contrail is about the same height above the horizon as the track, but the land piece height in Google Earth is about twice the height in the photo:
    Screen Shot 2016-12-01 at 19.51.16.
     
  32. Clouds Givemethewillies

    Clouds Givemethewillies Active Member

    Big tide!
     
  33. Jay Reynolds

    Jay Reynolds Senior Member

    Congratulations on the long range spotting! I had calculated 219 miles sans distortion...
     
  34. Clouds Givemethewillies

    Clouds Givemethewillies Active Member

  35. Trailspotter

    Trailspotter Senior Member

    It was for 30000 ft (6 miles) altitude, whereas UAE205 was at a higher altitude of 36000 ft (7 miles). For this altitude your formula gives about 236 miles, that is very close to the observed distance.:cool:
     
  36. Mick West

    Mick West Administrator Staff Member

    Jay used some approximate numbers:
    You can just stick in the Viewer height into a horizon calculator for a more accurate number, 36000 feet gives a horizon distance of 232 miles.

    https://www.metabunk.org/curve/?d=1&h=36000&r=3959&u=i&a=n&fd=60&fp=3264

    if you get a plane at FL450 that extends it to 260 miles.
     
  37. Trailspotter

    Trailspotter Senior Member

    And what would the distance be for the observer being at 50 meters above sea level?
     
  38. Mick West

    Mick West Administrator Staff Member

    about 248 miles

    The maximum visible distance from you to a plane is your distance to the horizon plus the plane's distance to the horizon. You can just do the horizon calculation twice, or for view height h and plane height p, it's
    sqrt(h*h+2*r*h) + sqrt(p^p+2*r*p)
     
    Last edited: Dec 1, 2016
    • Agree Agree x 1
  39. Clouds Givemethewillies

    Clouds Givemethewillies Active Member

    I found a good match for the land but lost the track..
    I needed to set 50m above _sea level_ to get a good match to the view from my window, distant.PNG
     
  40. Trailspotter

    Trailspotter Senior Member

    But you set FOV of 1.86° (no digital zoom) and got about the same fit as I did in the first attempt above (#62). I have reproduced your fit, the trail is still about twice higher than the track.

    Perhaps it was a secret sprayer deployed to thwart you record attempt by flying parallel to UAE205 and closer to your location ;)
    Or there was an atmospheric refraction lifting up the trail appearance by a small fraction of one degree…