That makes sense... I didn't realize that contrails dissipated so
quickly in dryer air. But it makes sense if the air is more humid that
the contrail would persist longer. The optical aberration seems logical
enough too and could explain the seemingly larger leading edge.
Combination of bad optics, dry air, hazy day, and setting sun equals
fireballs that last more than 4 minutes.... No wonder it looks like a
fireball.
Regards,
Eric
Chris Peterson wrote:
In fairly still air, contrails persist until they evaporate. How long
that takes depends on the humidity and water content of the air. I use
contrail patterns during the day as a tool to assess probable
astronomical seeing conditions that night. I'm looking for still, dry
air. I know that's what we've got when airplanes leave no contrails,
or leave contrails that only persist for a very short distance behind
the plane- like what the video shows. Here over the central Rockies,
such short contrails are very common.
Contrails normally form off the trailing surface of the wings, and
spread out with distance. In still air, they may spread very little,
and appear to taper away again at the far end. But what you usually
see then is a small start, some broadening, and then the taper begins.
This thing in the video seems too large at the start, which is why I
speculated that something was being vented.
That said, it's also possible the problem is optical. The camera
optics don't seem very good, and the image doesn't seem well focused.
So the apparent blob of material at the head might just be an optical
aberration of some sort.
Chris
*****************************************
Chris L Peterson
Cloudbait Observatory
http://www.cloudbait.com
----- Original Message ----- From: "Meteorites USA"
<[email protected]>
To: "Chris Peterson" <[email protected]>;
<[email protected]>
Sent: Monday, May 18, 2009 9:38 AM
Subject: Re: [meteorite-list] Huge Daylight Fireball Video?
Yeah, I though it odd.... Hence the ? mark.
I did notice the sun setting (or rising) and thought this could
possibly explain the orange glow of the "fireball" if it is contrails
reflecting the orange glow from beyond the horizon.
Still though, if it were a contrail from an airplane wouldn't it
persist in the air longer than it does? The "tail" of this fireball
seems to stay the same length through out the video and not stretch
out across all the way across the sky like a contrail would. Why is
that?
Don't contrails from planes tend to get larger further from the
aircraft as the trail expands and dissipates in the air? This video
shows a tapering of the short "contrail" seemingly getting smaller
the further away from the object. What would cause that?
Or is it only seeming to taper off because of the haze in the air
explaining why the longer "contrail" is not visible as well?
Regards,
Eric
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Regards,
Eric Wichman
Meteorites USA
http://www.meteoritesusa.com
904-236-5394
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