(meteorobs) Superbolide energy vs. meteorite drop

[Roberto G.]

>From: "Jure Atanackov"
>
> With regard to large fireballs and superbolides - I've been studying and
> reading a lot about superbolides and meteorite impacts lately and it seems
> to me that most of the recent significant meteorite falls come from (as
> far as superbolides go) rather unspectacular events with <0.1 kt energy,
> for example the Mbale, St. Robert and Villalbeto de la Pena. Park
> Forrest (~0.5 kt) and Tagish Lake (>1.5 kt), probably also the recent
> Carancas event seem to be about the most energetic events associated
> with recorded meteor drops.
>
> Is there a certain mechanism that prevents larger objects measuring in
> tens of  kilotons, such as the Mediterranean event of June 6th, 2002
> or the Marshall islands fireball of February 1st, 1994 up to prehaps
> Tunguska size to produce substantial meteorite drops or do such events
> produce proportionally larger meteorite drops measuring in tons and
> tens of tons, but are just very very rare?
>
> Clear skies!
> Jure

Sorry for the bad English.

You not remember or known that there are two type of events:
for a speed of 20-30 Km/sec a body has around 60 its pound
in TNT energy and a body that enter in the Earth atmosphere can do, for the
ablation effect, only a meteorite of 1-5 Kg, then for this meteorite you
have in general a bolid as the Full Moon (-12,7a) and only 0.006 kt
in power, but there are two severe guardians for to have a meteorite,
the first that the speed must not exced 30 km/sec or the body shall be
completly burn, the second it's that the body must to have imperatively
a enter angle in the atmosfere between 2° and 4° toward down, out
of this little way the body shall burn entirely: naturally this it's valid
only for body under 1,000 Tn, for an asteroid the Earth atmosphere
not exist!
There is too an other factor: the type of material, if this it's of cometary
origin as near all meteors, the Earth atmophere shall break in dust
when it's around 10 Km in hight from the surface, and you must remember
too that half comets have retrograd orbits, then with 42 Km/sec or more, in 
this
way you can understand that a big meteoroid body for exemple of
1,000 Tn can to be destroied by atmosphere but a bis stone of 100 Kg
can to do a meteorite of 5 Kg (break in many pieces).
If a cometary body enter in the Earth atmosphere with the good
angolation and speed it shall go certainly until the ground and
certainly shall origin meteorites and craters.
Then when we see a big meteoritical phaenomenon we must remember
tha the end of it come from its origin, asteroidal o cometary, and
its speek, newly asteroidal or comeraty.
Best greetings.
Roberto Gorelli