[meteorite-list] Meteorites 101-Bolide

[MEM]

We differ some Mark, in that a bolide is not just a fireball showing  
framentation-- such as we saw in the Peekskill fireball.  IMO, historically and 
by traditional use: a bolide is not just a simple fragmentation but an explosive 
rupture which occurs at the practical end of incandescent flight--Like an upside 
down bottle rocket.  Perhaps, it is somewhat subjective, and while it may occur 
out of ear shod, the explosive expansion part has a distinct sound/report 
different from a sonic boom.  The term was adapted possibly from a discussion of 
military rocketry into early descriptions of meteor fireballs which exploded.

Perhaps it is just me but I subscribe to these characteristics of a bolide 
because it describes a specific combination of conditions. The audible report 
component is most always associated with the early literature accounts 
describing a fireball as a bolide.  In my bolide theory I believe there is an 
envelope of stress/shear as the meteoroid is undergoing, being dramatically 
slowed by the atmosphere. If the envelope is not violated the meator may 
fragment but it does not do so explosively.  Around 5 miles above sea level the 
meteoroid encounters the boundary of that momentum /shear envelope which 
reflects maximum aerodynamic pressure at which the meteoroid can retain 
integrity.   This transition is so abrupt for the meteoroid, that it literally 
shears along molecular bonds releasing a fair amount of heat and possibly rapid 
oxidation of iron particles, etc. 


Elton



----- Original Message ----
> From: Mark Bowling <minador at yahoo.com>
> To: meteorite-list at meteoritecentral.com
> Sent: Sun, January 16, 2011 12:11:03 PM
> Subject: Re: [meteorite-list] Meteorites 101-Bolide
> 
> Hi all,
> I have understood from my study that a bolide refers to a meteor that  breaks 
>up 
>
> - not requiring the detection of an audible report because, if  observed from a 
>
> distance, the sound may not be heard.  It is not a bright  meteor or fireball 
>or 
>
> large impactor, but simply a meteor that breaks up.   Right or wrong, that's 
>the 
>
> way I've been using the term when I report seeing  one on the list.  Has 
>anybody 
>
> else been using it that way?  I've been lucky  to have seen several dozen over 

> the years (often colorful), but none up  close like Elton (yet!).
> 
> I would agree that the IAU should come up with a  definition because the 
>term has 
>
> come to mean too many things and its use  is not going to go away any time 
>soon.  
>
> In fact with the current explosion  of public interest (no pun intended), more 

> people are going to find the term  and grab onto it.
> 
> See you all soon!
> Mark B.
> Vail,  AZ