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Meteor Explodes over Massachusetts

nbcboston.com

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Re: Meteor Explodes over Massachusetts

#101

Post by jojobas »

margalabargala wrote: post #98
jojobas wrote: post #37

Earlier quoted context omitted.

No, it's a misnomer as with any other meteor. If you were to witness the breakup from the bolide's reference frame and without all the rushing air you'd never call it an explosion.

> and without all the rushing air That's the exploding bit though. You don't need containment, you just need the the airburst. A hyper-heated pocket of air that then expands rapidly is itself an explosion.

>then expands rapidly

Except it doesn't. The breakup has roughly the same dynamics as dirt spreading as it gets out of a tip truck. The shockwave is not produced by the outward motion, it barely has any speed.

Re: Meteor Explodes over Massachusetts

#102

Post by jojobas »

bmelton wrote: post #57
jojobas wrote: post #8

Earlier quoted context omitted.

No? There is no violent expansion or bursting, even if the sound is similar. It is as much an explosion as a supersonic jet passing by, and that is not much. The term makes people think atmospheric heating causes an actual steam explosion and that's the source of shockwave, which can't be further from truth.

Meteor Chelyabinsk suffered catastrophic fragmentation, a rapid, violent release of energy accompanied by a pressure wave with debris, which would satisfy the definition of an explosion (an in fact the energy released was equivalent to 400-500 kilotons of TNT.)

If you could look at this catastrophic fragmentation you'd find it's about the same pace as dirt spreading on the ground as it gets tipped off a dump truck. The fragments outward speed is negligible compared with their forwards speed, and it's the forward speed that produces the shockwave, fragmented or not.

Re: Meteor Explodes over Massachusetts

#103

Post by jojobas »

adrian_b wrote: post #54
jojobas wrote: post #14

Earlier quoted context omitted.

The speed scale for disassembly is nowhere near the forward speed; you never get anywhere close to 45 degree debris divergence angle. It's also, again, not the disassembly that causes it to be bright, hot and loud. Wikipedians can also be wrong.

Some meteors do explode. The meteors made only of iron alloy and/or silicate rocks do not explode, but they may fragment into many smaller bodies. The meteors that contain great amounts of volatile substances (water, carbon compounds and sulfur compounds) may explode if the interior becomes hot enough to convert the volatiles into gases. When such a meteor rich in volatiles fragments, some of the fragments may explod…

This fragmentation is not violent and it's not what produces the shockwave, the term "break up" is more appropriate.

Re: Meteor Explodes over Massachusetts

#104

Post by margalabargala »

jojobas wrote: post #101
margalabargala wrote: post #98

Earlier quoted context omitted.

> and without all the rushing air That's the exploding bit though. You don't need containment, you just need the the airburst. A hyper-heated pocket of air that then expands rapidly is itself an explosion.

>then expands rapidly Except it doesn't. The breakup has roughly the same dynamics as dirt spreading as it gets out of a tip truck. The shockwave is not produced by the outward motion, it barely has any speed.

You're conflating the outward motion of the rock with the outward motion of the air.

The shockwave is traveling at the speed of sound.

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