The filaments at the red pointer. Is that the result of shockwave?
i've often wondered the same thing regard that pic (or one very similar to it).
maybe it's blackbirds being toasted midflight.
Offhand, I believe those are smoke streamers deliberately deployed to observe air movement.
[ EDIT: http://en.wikipedia.org/wiki/Mushroom_cloud#Physics" ]
"...the streaks of smoke ... are vertical smoke flares which are used to observe the shockwave..."
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