In a recently published paper, atmospheric scientists specializing in contrails were asked what caused various photographed phenomena that "chemtrail" believers frequently identified as evidence of a secret large scale atmospheric spraying program. They unanimously identified the photos as ordinary contrails, and gave physical explanations for the various things shown in them. As a response to this paper (which also covered chemical tests, and of which I am a co-author), the web site "Geoengineering Watch" published a response, the most prominent part of which being a video of a jet leaving a trail, titled "Irrefutable Film Footage Of Climate Engineering Aerosol Spraying". Source: https://www.youtube.com/watch?v=iK9nVR9H34g With the accompanying narration set to dramatic music: And the video description: The video actually shows an aerodynamic contrail. It's caused by the drop in pressure over the wing causing water to condense out of humid air. It goes on and off because humidity is sometimes patchy, as seen by clouds being sometime patchy. http://www.pa.op.dlr.de/~pa1c/JAS66_217-226_2009.pdf The "deepest gratitude" to Douglas Huang seems somewhat misplaced, according to this account: http://www.shiftfrequency.com/chemtrail-spraying-video-proof/ However, the provenance of the video is unimportant, because what it shows is simply the well understood phenomenon of a persistent aerodynamic contrail. While this is a nice example, there are many other video examples that show aerodynamic contrails and the on/off behavior due to flying through patchy humidity. Source: https://www.youtube.com/watch?v=t22wy4c-A-A Source: https://www.youtube.com/watch?v=yZNtfWf76Hw Source: https://www.youtube.com/watch?v=OKSE4YYl6oM Source: https://www.youtube.com/watch?v=dHH8CL2KD3o And countless photos: One photo including an aerodynamic portion to the contrail was included in the study: The 49 contrail experts were asked about this. They all said the photo showed contrails, (although their explanations of the colors varied slightly between refraction and diffraction). Here are some of their comments (note these are from survey responses, and so several contain typos): The scientists were also asked about another phenomenon seen in the video, the "on/off" behavior. Again this was explained as a normal phenomena. Now the photo used was of an exhaust contrail (from the engine), not the aerodynamic contrail (from the wing), but the basic principles of uneven atmospheric humidity are the same. Here are some of the scientists comments: So, aerodynamic contrails are a familiar and well understood thing. Variations in atmospheric humidity are also familiar and well understood. This video, like many similar videos and photos shows aerodynamic contrails and variations in atmospheric humidity. Consider also what was written in the description of the video: This is utterly wrong, for two reasons: It is not an exhaust contrail - It's an aerodynamic contrail. It has nothing to do with the engines This type of jet engine makes MORE contrails. The idea that high bypass jet engines cannot make contrails is one of the most nonsensical claims ever put forward by the chemtrail community. Jet engines make water. The amount of bypass air does not change this. This claim has been refuted in great depth here. It's difficult to see why people take GeoengineeringWatch.org seriously. They have repeatedly made "irrefutable" clams like these, only to have them refuted, and then the refutations ignored. For example a very similar claim was made two years ago, in a video titled "Undeniable Footage of Jet Aircraft Spraying" Again this simply proved to be an aerodynamic contrail (this time between some exhaust contrails, as in the study photo). And this was explained in great depth in this thread: https://www.metabunk.org/debunked-d...ircraft-spraying-aerodynamic-contrails.t4454/ Another "undeniable" and "inarguable" piece of evidence from last year Was just a well documented fuel dump from a Thai Airways 777 flying from Munich. This was extensively documented here: https://www.metabunk.org/new-fuel-dump-chemtrail-video-munich-thai-airways-flight-925.t6541/ Geoengineeringwatch has a long history of being informed of their mistakes, and then ignoring the corrections, and simply doubling down by repeating the same mistake. A good example of their immunity to corrections is their "Extensive list of Patents" (used as an example of something we should have shown the scientists). Over two years ago I wrote about this list, and noted it included a device for indicating the toner level in a photocopier. But as of today that patent is still in the list. In fact all the pieces of "evidence" that GEW used to "rebut" the study have been discussed, and debunked here, usually years ago. The NOAA "gag order", the "historical documents", the patents, high bypass engines, "retrofitted nozzles", "global dimming", tests for aluminum, ozone destruction, biosphere freefall, and legal actions. All discussed, mostly debunked years ago. But ignored, and then regurgitated by Geoengineering Watch. I do not expect this pattern to change. But I hope that people can at the very least have a look at aerodynamic contrails and recognize that videos of them are not "irrefutable" or "inarguable" evidence of anything other than normal atmospheric physics.