A breakup will increase surface area and therefore kinetic energy to shockwave transfer efficiency, still not an explosion.
It would however, be incorrect to claim that the meteor had noting to do with explosions.
PSA: expressing an opinion (incorrect or otherwise) is not actually a public service announcement
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.
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.
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.
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.
The shockwave is traveling at the speed of sound.
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 explode, while others may reach the surface of the Earth intact.
PSA is false.
https://www.nasa.gov/blogs/watch-the-skies/2026/03/26/its-fi...
NASA states: "the fragmentation of the fireball unleashes large amounts of energy, which also generates a pressure wave that can produce a very loud boom, even shaking houses."
Fragmentation of a fireball, whilst not explosive itself (the particles needn't diverge at a supersonic relative velocity) are nonetheless part of a supersonic / hypersonic particle field relative to the atmosphere they are passing through. Expanding the diameter of that particle field will increase the size of the resultant shockwave, whether the particle separation itself is "explosive" or not.
The "explosion" then is of the deceleration (aerobraking) shockwave, not the bolide separation. But the bolide separation increases the intensity of the shockwave, with more (and lighter) particles interacting with the atmosphere over a shorter distance than an intact, small-diameter bolide would.
Some of this depends on what definition of "explosion" one chooses, or whether people are intending an explosion specifically, or an explosive sound (sonic boom). That's confounded by bolide separation, the bright light emitted on entry, and sonic effects, all of which are semantically associated with other explosive events. Language is a consensus phenomenon.
I'd tend to call the event an explosion, though not in the expanding particle field sense.
This is the same like how many kinds of water containing things, e.g. raw meat, eggs, fruits, can explode in a microwave oven if the microwave power is too high.
The meteor bodies belong to several classes of chemical compositions. Some of them contain very little volatiles, and they are made either of iron alloy or of silicate rocks or of a mixture of iron alloy and silicate rocks. These do not explode, at most they fragment into many smaller bodies.
Other classes contain great amounts of volatiles, e.g. water, organic compounds and sulfur compounds, and they frequently explode, depending on their size, shape and trajectory, i.e. if there is enough time for the interior to be heated to high temperatures, causing the phase change of the volatiles to gases.
Meteors and eggs do not normally explode, but under the right circumstances.. Boom!
I didn't state that the shockwave is independent of whether or not the body breaks up, I wrote, emphasised, "Expanding the diameter of that particle field will increase the size of the resultant shockwave, whether the particle separation itself is "explosive" or not."
Which your article (partially read, sorry, incredibly shitty reader) largely substantiates, largely in the itemised list in section 2.2. Pancaking of a bolide through fragmentation increases frontal area, has multiple points of mass interacting with the atmosphere over a larger area and with less mass at each point, and the (undiscussed) light-emission mechanism which itself largely derives from compressive heating and ionisation of the atmosphere (rather than friction against the atmosphere or heating of bolide particles themselves). Increasing the number, and surface areas, of particles increases the region and intensity of this effect.
As your source discusses, most fragmentation is a result of mechanical rather than thermal forcing of the bolide.
"jojobas and NASA's statements aren't contradictory."
jojobas wrote:
"PSA: meteors have nothing to do with explosions."
>You're being excessively argumentative.
You're defending idiocy. The PSA is false. There is science behind it. There is little nuance to salvage in any of it.
Breakup, impact, fly-by? all those could be incorrect if all you know is a space object entered the atmosphere, made a sound, and flashed some light. What do you call that? Especially because you don't automatically know if it impacted the surface. At which point it becomes a meteorite, so even calling it a meteor is not fully correct. Or do you get ultra technical and say that when it made the sound and flash, it had not yet reached the ground, therefore it was a meteor at the time?