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First - the footage of the explosion in question:

http://www.discovery.com/tv-shows/mythbusters/videos/homemade-diamond-high-speed/

More specifically, about 5 seconds in,

enter image description here

I'm speaking of the flash of light above the explosion.

The explosion was described as "a 20 foot high wooden tube packed with 5,000 pounds of high explosives."

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  • $\begingroup$ At a guess, some of the top part of the explosive was boosted as a rocket from the mass bellow and is exploding in air. The cone must be gas material from ejection $\endgroup$
    – anna v
    Feb 23, 2015 at 5:21

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It's internal reflection in the camera. It's an inverted image of the actual exploding material.

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  • $\begingroup$ I think so too - explosion is extremely bright with high contrast. You sometimes see this with sun, but usually conditions are not so extreme and it's less visible. It's sometimes called flare or lens flare en.wikipedia.org/wiki/Lens_flare $\endgroup$
    – Jarosław Komar
    Feb 23, 2015 at 5:27
  • $\begingroup$ you are wrong. If you watch the video frame frame, the ball and cone fall @JarosławKomar. It is a flaming ball with its gass exhaust. $\endgroup$
    – anna v
    Feb 23, 2015 at 5:28
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    $\begingroup$ It's a reflection of the exploding material. As the material is rising in the frame, the reflection is moving down. $\endgroup$
    – BowlOfRed
    Feb 23, 2015 at 5:32
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    $\begingroup$ And this is not necessarily wholly internal. Probably they've put some protective glass shield (just like you would use UV filter which does nothing to photo if you are below say 4000 m a.s.l. but protects lens mechanically) in front of camera. More likely than not this is back reflection from lens reflected back from this protective glass. $\endgroup$
    – Jarosław Komar
    Feb 23, 2015 at 5:43
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    $\begingroup$ The reflected image will always be (much) lower intensity. That means that in cases where the primary is very overexposed, the reflected image can actually appear sharper. $\endgroup$
    – BowlOfRed
    Feb 23, 2015 at 6:46
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Watching the video frame frame one sees that an incandescent ball is falling and a tail of gasses follows. The ball must have been ejected from the tube by the rest of the explosion, like a rocket, and falling, generates a tail of incandescent gasses.

My argument against a reflection is that the ball ( falling in my view) and its cone/fan tail are too symmetric to be a reflection of the total mess on the ground.

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  • $\begingroup$ It is pretty, much nicer than the lower part. That's because it's enough dimmer that you can't see the reflected "mess". Also, if you step through the frames, you'll see that the upper image appears simultaneously with the lower. This cannot be an ejected ball, since at those speeds it would not possibly have reached its peak height in a few milliseconds - you'd see it rising. Also, note the bright rectangle at the top of the lower cone- clearly a lens artifact since it is stationary. $\endgroup$
    – WhatRoughBeast
    May 2, 2015 at 4:29

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