[meteorite-list] Huge Daylight Fireball Video?

[Chris Peterson]

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" <eric at meteoritesusa.com>
To: "Chris Peterson" <clp at alumni.caltech.edu>; 
<meteorite-list at meteoritecentral.com>
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