[Farmer Dean]

Notice the 3 protruding jets at the base of the explosion.What is that?

[Nifster]

Part of the reaction.....charge shaping is critical and was tested a lot. The first one shows it to but after a while.

[Rebelbase]

Rosie O’Donnel’s arm and two legs after feeding at the trough?

[Attention Surplus Disorder]

“Notice the 3 protruding jets at the base of the explosion.What is that?”

Several of those bombs were floated in tethered balloons at modest height. The jets are the steel mooring cables vaporizing, possibly with some secondary effects with streams of particles bombarding the metal vapor.

[ctdonath2]

I’ll second #37.
Some were detonated on towers or balloons for elevation studies. The blast was able to progress down the guy wires faster than thru air, leading to the “spike” effect.

[Steely Tom]

Notice the 3 protruding jets at the base of the explosion.What is that?

Google the words "rope trick" and you'll get complete explanation.

[SpaceBar]

Those downward pointing “jets” are the steel tower legs vaporizing.