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

[stange]

Just a few of many sources and opinions on it all. Even read references 
before on surface melting in IMO somewhere and in AMS and NASA etc.,

Can't locate the original formal document that described & a great 
illustration of the ram-pressure boundry with the small boundry zone of the 
slower frontal surface gas flow causing a state of melted material ablation 
which can occur in fireballs and meteors. These are only a few that mention 
the types of melt conditions that can occur. Its all theoretical.....

http://www.springerlink.com/content/c53q37752640673w/fulltext.html

http://adsabs.harvard.edu/full/1952ApJ...116..203T

http://ntrs.nasa.gov/search.jsp?R=382817&id=5&qs=N%3D4294937611

YCS

--- Original Message ----- 

From: "stange" <stange34 at sbcglobal.net>
To: "Global Meteor Observing Forum" <meteorobs at meteorobs.org>
Sent: 2008/07/08 17:00
Subject: Re: (meteorobs) Ist Light...and it's hot!


> Hello Chris,
>
> Interesting, the two types of ablation yielding light & heat. I have not
> taken the time to read the collision theory. I suppose it is the raising 
> of
> K & L shell electrons to a higher state of energy, (K shell can total 2) 
> (L
> shell can total 6) since it is primarily Hydrogen(H1 & N7) involved which
> upon return to their lower state emminate energy in the form of heat & 
> light
> for the collision types.
>
> My understanding of the ram-pressure ablation is that there is a thin zone
> between the ram pressure heating zone and the meteoritic material  which 
> is
> of a (much slower velocity), removing the heated (molten) meteoritic
> material layer by layer.similar to a flow of hot gasses streaming around 
> and
> off the frontal area of the meteor during its flight. The inside 
> temperature
> is unknown to me, and I accept (your) cool interior because of the 
> enormous
> velocity of the object and the short period of flight.
>
> Then, jumping ahead a bit,  I suppose after ram-pressure & ablation of the
> larger mass, has made a progressively smaller mass, it would perform a
> transition to a collision phase of light & heat?
>
> Larry
> YCS
>
> ----- Original Message ----- 
> From: "Chris Peterson" <clp at alumni.caltech.edu>
> To: "Global Meteor Observing Forum" <meteorobs at meteorobs.org>
> Sent: 2008/07/08 15:47
> Subject: Re: (meteorobs) Ist Light...and it's hot!
>
>
>> 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
>>
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