Atomic bombs make mushroom. It's well-known and we've seen many images of atomic experiments around the world. My question is, what causes the mushroom shape? Do conventional explosives like TNT and grenades also make mini-mushrooms? Is it a physical attribute of the explosion, or something specific to nuclear energy?
[Physics] Why do nuclear bombs make a mushroom
atmospheric scienceexplosionsfluid dynamicsnuclear-engineeringnuclear-physics
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The comment on this page
http://chemistry.about.com/od/photogalleries/ig/Nuclear-Tests-Photo-Gallery/Operation-Teapot-Test.htm
http://chemistry.about.com/b/2011/04/19/nuclear-explosion-lines-spikes.htm
says:
Sounding rockets or smoke flares may be launched just before a device explodes so that their vapor trails may be used to record the passage of the otherwise invisible shock wave.
To learn about every detail of these tests, contact your nearest FBI agent.
Never underestimate the power of googling.
I googled "high speed nuclear explosion photos" and got a large number of them. Here is one:
This image captures two common elements: the spikes (called "rope tricks") and an uneven surface shape
The duration of the exposure is typically 10 nanoseconds
At this stage of the detonation the surface of the fireball has a temperature of 20,000 degrees, three times hotter than the sun's surface. At such temperatures the amount of thermal radiation (light) given off is so enormous anything it touches is vaporized ahead of the expanding fireball. The three spikes in this image result from the guide wires supporting the tower on which the bomb was located absorbing enough heat to turn into light emitting plasma. Because thermal radiation travels faster than the fireball, the spikes extend out ahead of it.
p.s. I should have remembered one frame cameras, since I had been using "gun cameras" from WWII to get images of cosmic rays in spark chambers by triggering, back in 1967.
Best Answer
It's due to the Wikipedia: Rayleigh–Taylor instability: an instability of an interface between two fluids of different densities, which occurs when the lighter fluid is pushing the heavier fluid.
Hot air rises and colder goes down.
A mushroom cloud is formed by hot wet air:
Search for images or videos of 'Rayleigh–Taylor'.