Re: Unusual short lasting 'contrail' seen over Canberra, Australia

From: Fred Valcho (
Date: Mon Jan 18 2010 - 03:47:40 UTC

  • Next message: Fred Valcho: "Re: Unusual short lasting 'contrail' seen over Canberra, Australia"

    I agree with Brent, the aircraft was likely gaining altitude. The "swirling" motion (they look like miniature whirlpools) of the contrail is the shift between two opposing atmospheric layers, there is a very small eddy that can occur, or there could be very strong winds causing the trails to fly vertically in some cases. Contrails always disperse, your PIC is of water vapor, (versus some chemical as is source, which are known to fan out over time). It appears that yours was not high enough or cold enough to cause the vapor trail to freeze into droplets, just condensation, tus it did not stay. Check the local weather for temp, dew point and relative humidity. These are all clues to the days conditions.
    On another note, I have witnessed the "soap-on-a-rope? contrail over the top of the Sierra's. They seem to have come from a proto-type jet that turns the engine on and off to propel it to very high sonic speeds, perhaps mach 10 or greater. As far as I know, they were unmanned aircraft. Their base is in the Mohave desert.
    I'm moving to Spokane next week. Lenticulars are very popular around Mt. Rainer 24 hrs prior to a storm. They forecast the on-coming rain. I've seen some here in the San Jose, CA area, but nothing spectacular.
    ----- Original Message ----
    From: Brent Gordon <>
    Sent: Sun, January 17, 2010 11:09:21 AM
    Subject: Re: Unusual short lasting 'contrail' seen over Canberra, Australia
    My best guess is that your contrail was caused by a plane passing 
    through a layer of humid air while the plane was climbing to cruising 
    altitude.  A thin layer of humid air (say a few thousand feet thick) 
    between two layers of dry air would give a short contrail that would 
    dissipate quickly.
    As for the cloud picture on your blog, those are lenticular clouds.  See 
    On 1/16/2010 11:42 PM, Paul Floyd wrote:
    > Just wondering if anyone can help with the following.
    > At about 5.05 pm Australian Eastern Summer Time today, I have looked
    > up and seen a very short (maybe 10 degrees long) 'contrail'. I watched
    > it for a couple of minutes and it rapidly dissipated over that time.
    > It dissipated in a swirling manner.
    > I am wondering if there have been either any reports of either a small
    > air burst of a minor planet or a satellite entering the atmosphere
    > above Canberra?
    > I figure I would ask and look silly for asking rather than not asking.
    > My reason for doing so is the rapid dispersion of the trail and it's
    > shortness. The contrail was orientated approximately North South. This
    > is also approximately where a major flight path is over Canberra for
    > high flying jet aircraft - so that is the most logical explanation.
    > I will post an image on my blog at
    > later.
    > Regards,
    > Paul Floyd.
    > -------------------------------------------------------------------------
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