1. Mick West

    Mick West Administrator Staff Member

    20170727-084115-fnpws.

    An excellent example of intermittent contrail formation was posted by GeoengineeringWatch.org:

    Source: https://www.youtube.com/watch?v=--M4UXgcf_o
    Link to Original video here.

    The narrator blames it on spraying, but I think the clue is in the image at the top of this post - perpendicular to the trail are five parallel clouds that look like the result of rotors or wave in the air that often cause rippled clouds or rows of clouds.
    upload_2017-7-26_15-59-6.
    Image Source: https://cloudatlas.wmo.int/orographic-influence-on-the-leeward-side.html

    This suggests the contrail (which I think is largely aerodynamic) is flying though the invisible portion of the rotors or lee waves and the on-off is the result of the variations in the air between the up and down portions of the waves.
     
    Last edited: Aug 5, 2017
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  2. M Bornong

    M Bornong Senior Member

    They faded the video really quick when they showed the clouds in your capture.
     
  3. Mick West

    Mick West Administrator Staff Member

    If the time and location of the video were known then it would be trivial to find which plane it was. Wider shots would also help with determining the cloud conditions
     
  4. skephu

    skephu Senior Member

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  5. Mick West

    Mick West Administrator Staff Member

    1:30 PM ADT is 16:30 UTC.
     
  6. Mick West

    Mick West Administrator Staff Member

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  7. Mick West

    Mick West Administrator Staff Member

    Path (top of the lighter areas here) works great with with the sun viewed from Halifax. Need more precise location to be sure.
    20170726-182846-bgx8k.
     

    Attached Files:

    Last edited: Jul 26, 2017
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  8. Trailblazer

    Trailblazer Moderator Staff Member

    Once again they never seem to provide an answer to why contrails shouldn't have gaps in them but other clouds can and regularly do.
     
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  9. Trailspotter

    Trailspotter Senior Member

    This or similar contrail was captured by the Aqua MODIS satellite that passed over this general area at 16:43 UTC:
    [​IMG]
    https://go.nasa.gov/2tMkqnM
    There are a few dashes at the end near Halifax, whereas the rest is a contiguous line.
     
    Last edited: Jul 27, 2017
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  10. skephu

    skephu Senior Member

    The trail pieces seem to be moving relative to the sun.
    Beginning of the video:
    upload_2017-7-27_12-36-28.

    End of the video (about 30 s later):
    upload_2017-7-27_12-36-59.

    Shouldn't the lee waves be stationary?
     
  11. skephu

    skephu Senior Member

    Speed (and altitude) graph of ET501:
    upload_2017-7-27_13-3-48.

    It had quite a high speed around 16:30 UTC, it's near the peak of the speed curve. Around this time, its speed was increasing with some fluctuations:

    upload_2017-7-27_13-5-45.

    I wonder if they played with the engine power setting.
     
  12. Trailspotter

    Trailspotter Senior Member

    The ETH501 track matches well the contrail in the Aqua image:
    Halifax_ETH501_contrail.
    The contrail deviates from the track because of the westerly high-altitude wind at the time, but would have converged with it at the ETH501 position at 16:43 UTC, the time of the Aqua photo. The contrail dashes were formed when the plane indeed was flying over Halifax at about 16:35 UTC (1:35 PM local time) and then carried by the wind to the East.
     
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  13. Trailspotter

    Trailspotter Senior Member

    Last edited: Jul 27, 2017
  14. Mick West

    Mick West Administrator Staff Member

    Yes, I don't think these are local lee wave - that was just a suggestion I made before the location was known. Looking at the weather systems in MODIS there's a variety of wave/ripple/row clouds that reveal some underlying structure of the atmosphere.

    20170727-062418-tg73d.

    20170727-062438-krzba.
    20170727-062513-etl2t.
     
  15. Mick West

    Mick West Administrator Staff Member

    Aqua also shows six (or possibly eight) dashes in the right place. A lucky capture.
    20170727-063658-8x907.

    20170727-063445-da3xi.
     
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  16. Mick West

    Mick West Administrator Staff Member

  17. skephu

    skephu Senior Member

    Ground speed.
     
  18. Trailspotter

    Trailspotter Senior Member

    I found something here:
    At the maximum zoom, the contrail (but not the dashed end) can be seen in the image taken at about the same time as the Aqua image (+2 minutes):
    Screen Shot 2017-07-27 at 15.50.10.
     
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  19. Mick West

    Mick West Administrator Staff Member

  20. Mick West

    Mick West Administrator Staff Member

    So that a 100% match for Ethiopian 501
    20170727-083714-1j8gh.
    20170727-083644-cskcv.

    Viewpoint KMZ attached
     

    Attached Files:

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  21. Mick West

    Mick West Administrator Staff Member

    20170727-093407-hwwya.
    Here's the back 8 sections. There's two more but they did not auto-merge as the lens flare confused Photoshop. But this is good as it's rectilinear.
     
  22. Mick West

    Mick West Administrator Staff Member

    I've posted the identification of the plane on Dane Wigington's video. It will be interesting to see if there's a response.

    20170727-094458-zv5vd.

    However it does look like I'm banned there. Perhaps a more neutrally considered person could post the info. I posted:

    The flight has been identified as Ethiopian 501, at 31,000ft over Halifax, NS, on July 23 2017, video starting at 1:34 local time. It's a regular scheduled passenger flight. The original video is at: https://www.youtube.com/watch?v=3qSNKL_ooO4


    20170727-100932-b21f4.
     
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  23. Mick West

    Mick West Administrator Staff Member

  24. Mick West

    Mick West Administrator Staff Member

  25. Trailspotter

    Trailspotter Senior Member

    Youtube automatically puts any comment with hyperlink to the spam bin, unless it comes from the approved person. The poster will see it, but other people won't. This can be circumvented by posting a partial link, e.g., watch?v=3qSNKL_ooO4
     
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  26. skephu

    skephu Senior Member

    Dane bans anyone making a critical comment. No chance posting there anything that can be construed as dissent.
     
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  27. Trailblazer

    Trailblazer Moderator Staff Member

  28. Mick West

    Mick West Administrator Staff Member

    • Funny Funny x 2
  29. Trailblazer

    Trailblazer Moderator Staff Member

    Seems to have disappeared?

    upload_2017-7-27_21-3-53.
     
  30. EricL

    EricL Member

    Okay, it happened to me too. I added a comment last night with a few general remarks about how such an observation would be seen as a nice indication of wavy atmospheric turbulence, plus a few comments about the general nature of these observations, and today, if I log in to YouTube, I can see my comment, but if I don't log in, my comment is gone. That tells me that the general public is not seeing what I wrote. Also, I didn't get a barrage of angry messages directed at me as would normally be the case on YouTube when disagreeing with a post attributing some everyday event to conspiracy or ghosts or whatever the case might be. No replies at all.

    I tried adding another remark, and it shows up just fine if I'm logged in, but again, it's invisible if I'm not logged in, so again I'm sure no one else can see it.

    It's just amazing, no, disappointing, to see the huge number of other comments just heaping praise upon this guy. There's not a single disagreeing comment in the bunch.
     
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  31. Clouds Givemethewillies

    Clouds Givemethewillies Active Member

    Aerodynamic contrails involve wing loading as a factor. Presumably this could be modulated by the vertical component of velocity of various types of atmospheric waves, which can be quite complex.. eg. "Gravity wave interactions around the jet stream" http://onlinelibrary.wiley.com/doi/10.1029/2002GL015783/full
     
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  32. Mick West

    Mick West Administrator Staff Member

    Interesting - I'd always assumed it would just be differences in the air temp/RH. The air movement direction might also be a factor - but it feels like that would be too small.
     
  33. Trailblazer

    Trailblazer Moderator Staff Member

    If the conditions are very marginal for contrail formation then I can see that small pressure variations over the wing could be enough to tip the balance one way or the other.
     
  34. Mick West

    Mick West Administrator Staff Member

    Maybe if things are very marginal - but I think the difference between the air in alternating up and downdrafts would be more significant - consider that it already is enough to cause clouds to form in rows nearby with no plane needed. So it's causing invisible "nearly cloud" regions in the updrafts just to the left (south) of the clouds here.
     
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  35. Trailblazer

    Trailblazer Moderator Staff Member

    Yes I agree that in this case it is almost certainly the updraft and downdrafts, as the gaps form a regular pattern characteristic of rotors or waves in the air.

    But when you see close-up video of aerodynamic contrails forming you often see more random and small-scale gaps which look more like they are caused by turbulent air flow and fluctuations in pressure. (No doubt local humidity etc is also varying, though.)

    Like this, for example:

    Source: https://youtu.be/yZNtfWf76Hw


    (Watch especially from about 0:30)

    IMG_3732.PNG
     
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  36. skephu

    skephu Senior Member

    The uploader of the original video has disabled the comments, thus the previous comments have also disappeared. Hmm...
     
  37. Clouds Givemethewillies

    Clouds Givemethewillies Active Member

    I don't think RH _variations_ are normally a factor in aerodynamic contrail formation (from memory), provided it is supersaturated. I suppose it could be just on the edge of saturation.
    Engine induced contrails tend to form, and the vary in length/persistence rather than suddenly turn on and off, but more rarely they can be just on the threshold of formation due to temperature, but persist if they form when RHi > 100%, as far as I can tell from limited observations.
     
  38. Trailblazer

    Trailblazer Moderator Staff Member

    Did the original uploader include the link to Geoengineering Watch when she first uploaded it? upload_2017-7-28_17-25-33.
     
  39. skephu

    skephu Senior Member

    Yes, I think so.
     
  40. Leifer

    Leifer Senior Member

    I'm glad to see this topic / video analysis is pinned.

    The video is being copied and used as "100% proof" of chemtrails, and also " the pilot must be sending us a message" (morse code or other sign).

    This thread removes many of the "guesses" that this video is generating..... if people decide to research it beyond a casual internet search.

    (Mick, is this thread attracting views ?)