Built on Facts

Conspiracies and Clouds

There’s a continuum of crazy in the world of conspiracy theories. On one end are the at least somewhat plausible ideas like that Oswald didn’t act alone in the JFK assassination. On the other end are the downright schizophrenically crazed theories, say that the world is actually run by evil reptilian aliens in disguise.

I’d put the chemtrail folks down toward that crazier end. They are of the opinion that the trails left by jet aircraft are in fact government chemicals of unknown but certainly nefarious purpose.

As Carl Brannen notes, if they haven’t put a conspiracy interpretation behind this they’re missing out:

i-5a3bd6fbf52153d10ee977e38fa03a29-plane.png

Roughly it’s akin to the phenomenon of breathing out on a cold day and the vapor-saturated air condenses into droplets when it cools. The mechanism is entirely different in this case, but the general concept is not so far removed – the air was able to support a level of water vapor, and now it can’t. Bam, visible water.

In the case of this F-22 and the other circumstances in which it’s observed (it’s not a new phenomenon at all) the thing that’s changing is pressure. As the shock wave passes the pressure drops, the water condenses. Once the shock wave has passed by, the droplets return to vapor almost instantly. More or less anything with a big shock wave can do this, not just aircraft. Here’s the Castle Bravo thermonuclear test, with the upper portion of the mushroom cloud formed by the same effect:

i-e06bb70a0113ecf101fbbb6ab20866e0-boom.png

Yet another variant of the effect was used in early particle physics. Subatomic particles move through supersaturated vapor in air and leave cloud tracks behind them. That technology is obsolete today, but it was instrumental in many early discoveries.

But even if it were only good for snazzy photos of airplanes, it would still be interesting.

Comments

  1. #1 D. C. Sessions
    July 8, 2009

    One of the few benefits to having a window seat on an airplane is watching the condensation forming in low-pressure areas over the wings. That, and in the tip vortices when landing in high humidity.

  2. #2 Quiet Desperation
    July 8, 2009

    Pfft! Everyone knows that the evil reptilian aliens killed JFK. Sheesh! Kids these days…

  3. #3 Uncle Al
    July 8, 2009

    http://wilk4.com/misc/f18.jpg
    http://img210.imageshack.us/img210/2653/herejy8.jpg
    Prandtl-Glauert condensation cloud
    http://www.yugatech.com/blog/wp-content/uploads/2006/09/cloud.jpg
    subsonic flow lines. 3-D wings are lofted by vortex shedding.

  4. #4 Rick Pikul
    July 8, 2009

    You left a bit out:

    It’s “evil kitten eating reptilian aliens”.

  5. #5 Colin
    July 8, 2009

    Crab people.

  6. #6 Thomas
    July 8, 2009

    Quiet Desperation, JFK killed JFK. Watch Red Dwarf to find out how and why.

  7. #7 Brando
    July 8, 2009

    Actually, to be a nuke test nitpicker, I suspect that’s Ivy Mike, not Castle Bravo.

  8. #8 Art
    July 8, 2009

    Some of the common claims from the chemtrails crowd are that aircraft must be spraying some unknown compounds because contrails are not continuous. They assume this is evidence that the spray is being turned off and on. When in fact it is easily shown to be a result of aircraft flying through different layers of atmosphere that have different temperatures and humidity.

    Another common claim is that jets over the last few decades produce denser and longer lasting contrails. This is a result of more modern and efficient high bypass engine designs being introduced. These denser contrails also last longer.

    The third claim is denser contrails formed by military jets demonstrates a government spraying campaign. What this really shows is that military jet engines are exempted from the more rigorous commercial pollution standards. Military aircraft are allowed, for obvious reasons, to release more particulates. These fine particulates form the nucleus around which water droplets condense. More and more efficient condensation means denser contrails.

  9. #9 CCPhysicist
    July 8, 2009

    Brando@6: Matt is correct. I linked the relevant resource for Castle Bravo in my blog today that points to this amusing article, as well as the conspiracy theory subject Matt should take up next: Michael Jackson’s ghost.

    http://jezebel.com/5308704/youtube-commenters-weigh-in-on-michael-jacksons-ghost

    I hereby thank a commenter on FSP’s blog for that one!

  10. #10 Bob Hawkins
    July 9, 2009

    Yep, the F-22 picture has already been incorporated into the conspiracy. I saw a claim that the F-22 was built so chemtrails could be spread faster. It’s sort of the fast response team of chemtrails.

  11. #11 Thurston
    July 9, 2009

    A process, similar to the visible shock wave around the pictured F-22, can easily be reproduced at your favorite bar/pub/saloon. Take your beer bottle and tap its’ bottom down on to the top of your friend’s beer bottle. Your friend’s bottle will foam-up. As the medium in which the process occurs, beer, is a liquid the process is called cavitation. I can’t explain why the neck-tapped bottle is always the bottle that foams up. Are the evil reptilian Illuminati overlords messing with my beer?

  12. #12 Anonymous
    December 15, 2009

    Matt, you’re an idiot. If you’d come out of your stinking dormitory hole every now and look up then you’d notice.

  13. #13 Anonymous
    December 15, 2009

    Correction, that should be, “Matt, you’re an idiot. If you’d come out of your stinking dormitory hole every now and then and look up, you’d notice.”