1. Mick West

    Mick West Administrator Staff Member


    Source: https://www.youtube.com/watch?v=epa6WxEw1Xk


    This video by YouTuber LouB747 has been shared thousands of times on Facebook, and many people think it shows some kind of deliberate spraying, a "chemtrail".

    The video looks very odd if you don't know what you are looking it. It's a Boeing 787 that's flying more or less on an opposite track to Lou's plane, but about 1,000 feet lower. It starts out looking like this:

    20170620-163729-frenu.

    Similar videos have show up before, when the conditions, lighting, and angles are right. This one is from 2010.

    Source: https://www.youtube.com/watch?v=xl6iR7w7a_Q


    In the new video there's a similar combination of the right angle, perfect contrail conditions, and early morning light. At this point the trail is several miles long, but because we are looking almost head on it looks shorter and thicker than you would expect.

    Eventually it gets closer, and we can see that it's flying near head-on (but lower). It passes underneath Lou's plane.
    20170620-164013-qoca1.

    This resembles another famous photo, especially if we first color correct it for the orange sunlight
    20170620-164310-tygdx.

    Now compare with photo c here:
    [​IMG]

    The original photo C is from airliners.net.
    [​IMG]

    Photo C is one of four images that were included in the paper Quantifying expert consensus against the existence of a secret, large-scale atmospheric spraying program, of which I'm a co-author. In the paper we asked 49 contrail experts what they thought was going on in the photo - with additional focus on the colors seen in the middle. The results were summarised in the figure:
    20170620-164844-kcvs1.

    All the contrail scientists thought it was a contrail. They gave written answers in more detail, which are summarized below

    So all 49 contrail scientists think that trails like this one are just contrails
     
    Last edited: Jul 3, 2017
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  2. TWCobra

    TWCobra Senior Member

    One of the interesting features of this video is that the shockwaves always present over the wing of an aircraft approaching the transonic speed range are revealed by the aerodynamic contrail also being formed by the wing and fuselage.
    Even though this 787 was probably cruising about Mach 0.85 or thereabouts, there are areas of the aircraft where the airflow is moving at more than Mach 1.
     
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