Tiny mushroom cloud?

[PeterCrisp]

This may be a stupid question and if so sorry but how small in yield can a nuclear weapon be and still have a classic mushroom cloud? Would it be feasible for a nuke to be built so I could have a nice mushroom cloud rising from my desk if I scatter a handful of dust on it. I don't mean a huge cloud reaching to the ceiling just a small cloud maybe a few times bigger than a mug?
Something to make a dull day a bit less dull.

 

[Belesari]

This may be a stupid question and if so sorry but how small in yield can a nuclear weapon be and still have a classic mushroom cloud? Would it be feasible for a nuke to be built so I could have a nice mushroom cloud rising from my desk if I scatter a handful of dust on it. I don't mean a huge cloud reaching to the ceiling just a small cloud maybe a few times bigger than a mug?
Something to make a dull day a bit less dull.

LOL i dont know. I do know that there have been many trying to make nukes as small as even a gernade:rotfl

 

[Kilo 2-3]

Mushroom clouds are not limited to nuclear explosions. Volcanoes, large conventional bombs, industrial accidents have all triggered similar clouds. Tests of small nuclear weapons like the infamous 10-20t "nuclear bazooka" have yielded mushroom clouds, so somewhere in that range seems like threshold for mushroom cloud formation. Weather conditions would also play a factor.

 

[kato]

Basically, all you need is a fireball raising upwards into the air above some dust or earth. The problem is that the fireball has to be internally fuelled and maintained for a bit, which outrules conventional explosives and limits it effectively to fuel-air explosives, nukes etc. Gas fires for example may produce a similar effect for a very limited time, although not exactly the same.

You don't need a 10t nuclear explosive for a mushroom cloud though. 5 tons are easily enough, see Daisy Cutters.

 

[PeterCrisp]

So an executive toy nuke is a possibility? That would certainly grab attention at meetings .

 

[EXSSBN2005]

just scale it down a bit and like they say dont try it at home (try it outside first with a smaller version and nothing overhead) [nomedia="http://www.youtube.com/watch?v=yRw4ZRqmxOc"]YouTube - Mythbusters - Creamer Cannon[/nomedia]

also I believe the 10-20kt range they were refering to were the Davey Crocket recoiless rockets with the nuclear warheads in the range of 10-20 kt not 10 - ton weight of the actual device.

This video shows it in a smaller scale
[nomedia="http://www.youtube.com/watch?v=21o5zkbmYtA"]YouTube - Coffee Creamer Cannon[/nomedia]

As far as how small you can make it and still have the desired effect for say a boardroom if would be interesting to see it done, while this is not exactly a defence related topic I wonder if there is an active defence vs this type of improvised explosives as it can be made with flour iirc and large qantities of flour are not tracked to my knowledge, the setting of which could be disguised as installing sewer pipes. It pays to be observant, this is not ment to show novel explosives but it is not really practicle due to the time required for set up.

 

[My2Cents]

Basically, all you need is a fireball raising upwards into the air above some dust or earth. The problem is that the fireball has to be internally fuelled and maintained for a bit, which outrules conventional explosives and limits it effectively to fuel-air explosives, nukes etc. Gas fires for example may produce a similar effect for a very limited time, although not exactly the same.

You don't need a 10t nuclear explosive for a mushroom cloud though. 5 tons are easily enough, see Daisy Cutters.

Actually convention explosives work fine. Having an internally fueled cloud just guarantees that it will be visible for a while.

All you need is a large enough spherical volume of very hot gas (the cloud) near the ground. Physics dictates that the volume of hot gasses will rise and that air will be pulled in from the surrounding area to replace it, which picks up dust and debris, and is sucked up after the cloud. This debris is what makes the cloud of hot gases visible when it cools. The size and temperature of the cloud of gases is the key here, if the velocity of the inflow is not fast enough, or there is insufficient materials that can picked up, then the cloud will not be visible.

As the cloud rises a toroidal shaped internal circulating currents forms due to shear forces with the surrounding air and thermally generated flows. At the same time the cloud the rising gases are dissipating energy to rise and expanding due to lower pressure, both these processes cause the cloud to cool until it reaches equilibrium with its surroundings, stops rising, and spreads laterally to form the cap.

 

[kato]

also I believe the 10-20kt range they were refering to were the Davey Crocket recoiless rockets with the nuclear warheads in the range of 10-20 kt not 10 - ton weight of the actual device.

Actually the W54 warhead design, depending on version, could be set to 10 tons, 20 tons, 250 tons, 600 tons or 1 kt. Tests Little Feller I and Little Feller II detonated at 18 and 22 tons yield respectively, both set to the 20-ton yield.
Other sub-kiloton devices aside from the W54 were some units used in Plowshare with about 370 tons actual yield as well as the W48 155mm artillery warhead at 72 tons yield (per design). Supposedly the nuclear ammunition for the 2S7 could also be dialed down to about 100 tons.

Actually convention explosives work fine. Having an internally fueled cloud just guarantees that it will be visible for a while.

Yeah, but if we're talking visibility instead of a simple "puff" of smoke non-self-fueling superheated gas clouds won't last long...

 

[My2Cents]

Yeah, but if we're talking visibility instead of a simple "puff" of smoke non-self-fueling superheated gas clouds won't last long...

No, they just need to be big enough to pick up the material to remain visible. They did some test with multi-kiloton piles of ANFO for nuclear simulations that generated perfect mushroom clouds.

And the self fueling ones disappear quickly as soon as the fuel runs out.