(meteorobs) Ist Light...and it's hot!

[Chris Peterson]

Hi Larry-

This fireball is probably large enough that ram pressure is responsible for 
its heating, but that isn't always the case. For a mass smaller than a few 
millimeters (which can still produce a significant fireball), it isn't ram 
pressure that produces heating but collisions with air molecules. This is a 
direct consequence of the small size of the object with respect to the 
rather large mean free path at high altitudes. Below a certain size, an 
object can't maintain a volume of compressed air in front of it.

In any case, there's no "molten mass" here. At any point along the path, the 
average temperature of the mass is barely above what it was before it 
encountered the atmosphere, most likely below freezing.

It's a nice fireball, about what an allsky camera should record once every 
week or two.

Chris

*****************************************
Chris L Peterson
Cloudbait Observatory
http://www.cloudbait.com


----- Original Message ----- 
From: "stange" <stange34 at sbcglobal.net>
To: "Global Meteor Observing Forum" <meteorobs at meteorobs.org>
Sent: Tuesday, July 08, 2008 3:56 PM
Subject: Re: (meteorobs) Ist Light...and it's hot!


> An effect of ram-air pressure heating the surface and interior of a mass
> however small, in a high velocity approach from outer space into the 
> earths
> upper atmosphere.
>
> A VERY nice first capture shown as a composite image of meteor ablation
> which is bright enough to be described as a fireball.
>
> Wish it had been my capture. -YCS