1. skephu

    skephu Senior Member

    Just recently someone in a discussion wrote that this video actually convinced them that chemtrails are real:

    Here, two planes fly almost parallel, and it is shown that their contrails have a well-defined starting point. They also seem to chase a third plane, which is, however, not contrailing.

    Please help me debunk this video.

    I know several similar videos and a number of explanations, including:
    1. Plane flies from dry into wet patch of air. However, it seems too abrupt in this case.

    2. Pilot suddenly increases throttle. There is a well-known video (debunked on this site) showing aerial refueling where this happens. However, there are two planes here and I guess they would not refuel simultaneously. I see no reason why they would go from no throttle to full throttle suddenly.

    3. It's not a contrail but a smoke trail which is switchable by the pilot like in skywriting. This is possible in this case but I don't see the purpose. It doesn't look like skywriting or aerobatics.

    What explanation would fit this case best? Also, what are these planes doing? In fact, it looks like there is a fourth plane as well but I'm not sure about that. And what about the third plane not leaving a trail? Different altitude?

    I searched the forums to see whether this video was discussed before but I didn't find anything. It's a difficult case to me.
  2. WeedWhacker

    WeedWhacker Senior Member

    This is actually the correct explanation. The "abrupt" appearance (or disappearance/stoppage) is simply a consequence of conditions aloft at altitude. The Earth's atmosphere is never homogenous,

    No this is an erroneous misconception

    Correct in that commercial airliners have no provisions for producing smoke trails, nor skywriting.

    Here is a related thread and discussion:
    Last edited: Apr 2, 2014
  3. skephu

    skephu Senior Member

    Thanks for your comments, WheedWhacker. However, I still cannot rule out either explanation.
    I agree that #1 may be correct. But all the real examples I have seen where a contrail was broken because of changing atmospheric conditions showed a more gradual change. There is a big difference in conditions favoring "no contrail" and "persistent contrail". Usually what happens is that the contrail is initially continuous but some parts fade away quickly while other parts persist. In this video the start of the contrail is very sharp with no fading, see the closeup at 0:35.

    I can't exclude explanation #2. I don't know why you think it is a misconception. This was the explanation for the AWACS refueling video, see this thread: https://www.metabunk.org/threads/awacs-being-refueled-with-off-on-contrails.816/

    And finally, these planes seem to be military jets flying in some formation. I don't think they are commercial planes. So some type of smoke trail is also possible.

    Unfortunately the video is short and the planes are almost invisible, so we have very few clues to find out what's really happening.
    Also, I watched it again, and now I see there are indeed 4 planes. One of them is not contrailing at all. If they really fly in formation (presumably same altitude), this is also strange.
  4. pseacraft

    pseacraft Active Member

    Actually military fixed aircraft are not capable of producing smoke on command as a default capability just like commercial/private aircraft. Only those that have has special modifications to produce smoke such as test aircraft and flight demonstration aircraft. A few models, have the ability to dump fuel into the exhaust nozzle, such as the old F111 and I believe the SU-31/33 (might b wrong on the proper model). The F111 is now entirely retired form global service but was a famous bird for doing fantastic fuel dump n burns - hell of a sight at night.

    I think Weedwacker misunderstood your direction on #2, Refueling as explained in the video you referenced would result in the aircraft taking on fuel to 'throttle down' during the break away. Where as normal air traffic would not need to be performing throttle downs hence why the misconception of the throttle causing the broken contrails claimed to be switched on and off.

    Of interest the video you shared does not show aircraft being refueled, the formation is much too loose and one can not tell the differences in altitude which directly relates to contrailing or not between aircraft somewhat in the same proximity. Also depending on the tanker, certain configurations of the KC-135 uses multiple drogues, you can refuel two aircraft simultaneously - scroll through the wiki to see images of same: http://en.wikipedia.org/wiki/Aerial_refueling

    A contrail is nothing but a cloud induced by the byproducts of the aircrafts engine. And just like clouds they start and stop abruptly. Next time you go flying watch the clouds closely you will see some the tend to "fade" away like fog and others that look like solid walls with very fixed edges. The atmosphere is a fascinating place we know a lot but again a lot we do not know and its a living changing thing all the time everywhere.
    • Agree Agree x 2
  5. RyanBiv

    RyanBiv New Member

    Why does it seem 'too abrupt' in this case? To me it looks like any other examples of contrails starting/stopping as they move in and out of humid regions. Clouds can have abrupt, well-defined borders, so why wouldn't contrails be the same?

    The planes without contrails are flying at a different altitude.
    • Agree Agree x 3
  6. skephu

    skephu Senior Member

    All the examples of contrails starting/stopping because of moving into/out of humid regions I have seen so far show a more gradual fading away than what is visible in this video. Here there is no fading:

    If you look at the Appleman chart, for example, a wide region separates the conditions favoring "no contrail" and "persistent contrail". In this region, contrails form but dissipate more or less quickly.

    In the atmosphere, there must always be a transitional region between the dry and humid regions. It doesn't just jump from 0 percent to 120 percent of relative humidity. It would gradually increase over some distance. How small that distance can be, I'm not sure.

    The cloud analogy is not perfect. Just because the cloud has a sharp boundary it doesn't mean that the air is completely dry right next to the cloud. It may be high without a cloud forming, for example because condensation nuclei are not present or because the humidity is below the level needed for cloud formation. However, it is quite likely that if you fly a plane in that region, a contrail will form, even if not a persistent contrail, because the plane injects condensation nuclei and additional water into the atmosphere.

    That means that humid and dry regions do not simply correspond to regions inside and outside of clouds, respectively. The air can be humid where there is no cloud. A plane, however, will inject condensation nuclei, and will give you a good measurement of actual humidity. If there is absolutely no contrail that means that the air is very dry; a persistent contrail indicates a very humid region. And between the two, there must be a transitional region where contrails do form but don't persist. But in this video, it seems that there is a sharp switch from "no contrail at all" to "persistent contrail", i.e. no transitional region.

    Most observed instances of contrail gaps actually start from a continuous contrail from which some sections dissipate while others persist. A persistent contrail just jumping out of nothing seems implausible to me because it would indicate a sudden change from very dry to very humid. That's why I think explanations #2 and #3 in my opening post should be considered.
  7. WeedWhacker

    WeedWhacker Senior Member

    Glad you mentioned the Appleman Chart. However, your interpretation (of "abruptness") may be a slight misconception as to what that Chart is trying to indicate.

    There can indeed by substantially defined boundaries between airmasses of different humidity/Ph levels. Just as there is this phenomenon we call "wind shear". (Sometimes the reason for turbulence when you're an airline passenger, at altitude. There are other reasons {for turbulence} as well).

    #2 suggested aerial refueling, and that has been discounted by a post up above.

    #3 is....well, but I addressed that and will continue to call it fallacious. (It was the notion of "smoke trails" related to skywriting activities). To re-iterate: There is simply no provision on a modern large airliner (or ANY airliner going back for decades).

    Realizing that many who might not be familiar with aviation will attempt to find "reasons", there are simply some hypotheses that can be rejected immediately. In favor of actual science and known parameters of contrails, and their formation criteria and behavior.
    Last edited: Apr 3, 2014
  8. RyanBiv

    RyanBiv New Member

    I don't think "there must always be a transitional region", humidity can be vastly different within just a few feet. There are many many examples of contrails with no fading. See:



    • Agree Agree x 2
  9. solrey

    solrey Senior Member

    Your assumptions are incorrect. The change from humid to dry air can be very abrupt. For example, in the following radiosonde data from Dallas, TX the relative humidity drops from 83% to 10% within about 1,000 feet. Granted in this instance it does not occur at contrail altitude and the boundary is horizontal but it's just an example of what can happen at any altitude with a boundary in any orientation, including vertical.

    RH is 83% at 1396m and 10% at 1698m.


    So our scenario is a change from humid to dry air in just 1,000 feet. Now consider a passenger jet is between 200 and 250 feet long and at cruise travels around 800 feet per second. So a passenger jet would cover that 1,000 foot distance between humid and dry air in about one second... don't blink, you might miss it.
    • Agree Agree x 1
  10. skephu

    skephu Senior Member

    What does the speed have to do with anything? We are looking at a static image, see video screenshot above. It's distance, not time, what matters here.
    The measurement cited by you just confirms what I said. A 300-meter distance was needed for a transition from a dry to a humid region. That's not abrupt at all. The picture shows a much sharper boundary.
  11. WeedWhacker

    WeedWhacker Senior Member

    It was one still frame taken from a video of objects in motion. The airplanes that made the video are either (A) out of frame, or (B) too small to resolve using the camera's technical resolution ability in this particular video.

    You cited one example posted by another member to indicate ONE distinction that can naturally occur in the atmosphere.

    Earlier I noted that there can be more abrupt examples of a distinct boundary between two airmasses, each with very different conditions contained within.

    A "shear zone":

    (Wiki used the other term of "Wind Shear"). But that article was very broad in its description.

    Wind shear as a phenomenon is mostly studied as a danger to aviation near the surface, during takeoffs and landings. But, it is well-known to also occur at altitude, and as such, is largely not a hazard (except in the most extreme cases of 'CAT', or "Clear Air Turbulence"):

    Last edited: Apr 3, 2014
  12. skephu

    skephu Senior Member

    Actually, with the exception of the rocket contrail in the first page you linked, I find that the boundaries are more faded in all examples. That's kinda subjective though. However, the age of the photographed contrails also matters. If the photo shows an older contrail, we don't know whether the missing parts were there initially but dissipated, or they were not even formed. The video in the opening post shows a young contrail because we still see the planes. Even in the drier region, I would expect a non-persisting contrail still being somewhat visible. But it's not there. Unfortunately, the video doesn't show how the contrail started.
  13. WeedWhacker

    WeedWhacker Senior Member

    A rocket contrail example is actually (and I had forgotten this explanation) entirely pertinent!!

    The shearing of airmasses can occur on any angle of plane...horizontally, vertically, and all angles in-between. In THREE dimensions.
  14. skephu

    skephu Senior Member

    That's OK but the rocket contrail photo was probably taken some time after the rocket had passed.
    That contrail section may just be a persisting section of a longer contrail whose other parts dissipated by the time the photo was taken.
    We don't know because it's not on video.
  15. solrey

    solrey Senior Member

    That's just one example of radiosonde data I happened to look into recently and if you bothered to look at the data you'd also see that RH went from 77% to 20% in a little over 300 feet. 300 feet is just a bit longer than the length of a typical airliner. Often the transition from humid to dry air covers even less distance than that, even shorter than the length of the plane itself!

    For an observer on the ground, the width of an average thumb held at arms length more than covers a space of 300 - 1,000 feet at typical cruising altitudes of >30,000 feet.
    • Like Like x 1
  16. TEEJ

    TEEJ Senior Member

  17. RyanBiv

    RyanBiv New Member

    • Agree Agree x 1
  18. skephu

    skephu Senior Member

    Wow! That's quite possible. It looks like Indian Air Force had an exercise in the UK from July 2-12, 2007, just a few days after this video was shot.

    If those are really the SU-30s with the "party trick" in the video then I would bet that my explanation #3 is the right one.
  19. WeedWhacker

    WeedWhacker Senior Member

    A fuel jettison ignited on purpose by a military fighter is very different from a condensation trail, of course. And, not possible (to be ignited) on a large commercial airliner. (Barring some mechanical problem, of course). Igniting the fuel, this I have no knowledge of (in military airplanes). Airshow display smoke is produced from oil injected into the hot exhaust region.

    An actual fuel dump (or, Jettison System) for large airplanes includes ONE nozzle per wing (for symmetry in weight distribution laterally) and
    the nozzle locations are designed to be well away from the engines, specifically to preclude any fire dangers:

    ATC Audio link to the above (edited only to remove unnecessary gaps):
    • Like Like x 1
  20. skephu

    skephu Senior Member

    No, no, we are not talking about fuel dump but this special system used in the SU-30s, described here:
  21. WeedWhacker

    WeedWhacker Senior Member

    Could be, but I am noting from the link that the SU-30 is a twin engine fighter (copied from the USA's F-14, likely).

    But, the original posted video is difficult to discern. However, a closer look shows a very "tight" location, of two tandem engines, with the inherent spreading into two distinct contrails just behind. This would comport with the arrangement of a military fighter twin-jet.

    So on a better look at the video, potentially a fuel ignition display, or simply regular contrails.
  22. TEEJ

    TEEJ Senior Member

    It does seem a bit of a coincidence and fits in nicely with the staggered formations of the two groups of 3 Su-30s? I have sent an e-mail to the Indian Air Force Public Relations Officer to see if the Su-30s did indeed perform their party trick while heading for RAF Waddington on the 28th June, 2007.

    Pluto and Titan formations were comprised of 3x Su-30s

    The following snippet from the media article has the names of the pilots and I have passed this onto the Indian Public Relations Officer.

    Group Captain Gerard Galway
    Public Relations Officer (PRO) Indian Air Force
    Directorate of Public Relations


    This following video appears to be the original? This is the link that I have sent to the Public Relations Officer.

  23. skephu

    skephu Senior Member

    Hey TEEJ! Have you ever gotten a response?
  24. TEEJ

    TEEJ Senior Member

    Hi Skephu,

    I have received no response.
  25. Efftup

    Efftup Senior Member

    Not quite sure why you think it needs to be copied from the USA's F14.
    The F15 looks a lot like the MiG 25 which first flew 8 years before the F15, so you could say it was a copy of the Russian but it was more likely just the prevailing science ended up with similar looking planes.
    The F14, F15, Tornado, MiG25 family, MiG29 family and Sukhoi 27 family all have the same shape air intakes as the earlier RA5 Vigilante of course.
    The F14 has a variable geometry wing like the Sukhoi 24 and MiG 23 that flew first and the Tornado that flew later.

    in 1947, you had the MiG15 and F86 that flew within months of each other but rather than one copying the other, it's just more likely that the prevailing design/science wisdom said swept back wings and stick the engine into the fuselage.

    it's actually amazing just how similar looking the Su27 and MiG 29 are. I had a hard time telling the difference a few years ago.
  26. MikeC

    MikeC Closed Account

    Looks a lot like edge of a bunch of clouds outside at the moment - they are quite "well defined" - although not at "contrail altitude".

    To paraphrase chemmies - "look up" and you will often se clouds with "sharp" edges because that is how different the atmosphere can be.
  27. DaveC426913

    DaveC426913 New Member

    I was referred to this thread from another science forum where I've been discussing this video.

    After much dialogue, I had enough information to draw up a diagram, which I hope explains what is happening in the video. Though I'd contribute it here.

  28. Hama Neggs

    Hama Neggs Senior Member

    I don't know if it's accurate to say that no condensation nuclei are present until a plane comes along.
  29. Mick West

    Mick West Administrator Staff Member

    It's not. While the condensation nuclei in the exhaust are involved in contrail formation, they are not required. There's usually plenty of nuclei in the air all them time (hence we get clouds)
  30. mazoola

    mazoola Member

    Strictly speaking, he says "in clear air" -- which sort of makes him right, in a tautological way. (If the air held nuclei, it wouldn't be clear, would it?) Of course, I'm not sure how real a thing truly clear air might be; my understanding was there is always some level of micro-particulate load....
  31. DaveC426913

    DaveC426913 New Member

    Yeah. It's a tricky balance of humidity, temperature and particulate thresholds. I'm not sure how to describe that in just a sentence or two. I want to get the gist, without writing a novel.

    Would welcome suggestions.
  32. Mick West

    Mick West Administrator Staff Member

    Then don't mention nuclei. It's pretty much irrelevant to the argument.
  33. Dan Page

    Dan Page Active Member

    The two jets making the trails appear to be at the same altitude, while a third one may be higher. To me, this looks like two military jets having a race. At the start of the trails they both went to full throttle and as they approached mach 1 they throttled back, one throttled way back, while the other one only throttled back just enough to stay below mach 1 for another couple miles, then he too throttled way back. The higher one may have been observing to see who won the race. If this was the case, it's unlikely you will get any official word on what they were doing. I have to agree with skephu, the start and stop of the trails just seem to be too abrupt. Anyway, that's my $.02 worth.
  34. skephu

    skephu Senior Member

    I thought we already concluded that what this video shows is probably a "party trick" fuel dump into the engine exhaust for show.
  35. skephu

    skephu Senior Member

    There are two kinds of nuclei: cloud condensation nuclei (CCN) and ice nuclei (IN). CCN are needed for water vapor to condense to liquid water; IN are needed for ice formation. There are plenty of CCN in the atmosphere at all times, but IN are rare. Supersaturation can occur because of the lack of IN. When an airplane comes along, its exhaust contains particles, mostly CCN, also some IN. But IN are not needed for contrail formation, as contrail formation occurs through a liquid phase: the exhaust condenses to liquid first which then freezes, and freezing occurs without IN below about -37 °C. So basically contrail formation does not require the particles emitted by the airplane. The particles make the contrail thicker and denser, but a contrail would form without the emitted particles.

    Also, contrail formation does not require supersaturated air. Supersaturation is only required for the persistence of contrails. Contrails can form in zero humidity air if the temperature is low enough. But the higher the ambient humidity the higher the maximum temperature where a contrail can form.
  36. Balance

    Balance Senior Member

    FWIW, I see three contrails at first, then the middle aircraft stops creating his, while the other two continue.
  37. Mick West

    Mick West Administrator Staff Member

    That seems the most likely. But it's not entirely case closed. Variable humidity (regional or altitude based) or engine settings are possible alternative. Without much more information it's hard to say exact how likely any particular explanation is.

    Of course the absence of a 100% winner does not then mean the 0.0001% probability is more likely. If we don't know exactly which of several possible methods were used to build the Pyramids, then that does not imply aliens built them.
  38. Hama Neggs

    Hama Neggs Senior Member

    Yeah. CTs seem to believe that there should be zero stuff in the atmosphere if it isn't put there artificially. Been trying to explain atmospheric dust and moisture to somebody who thinks sun rays are proof of geoengineering. :rolleyes: