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What a beautiful concept! Here are some tricky issues that immediately
spring to mind.

Outdoor pools of warm water and droplet clouds ring alarm bells about
Legionella infection. However, if these clouds are formed purely by
evaporation and condensation then I guess there's not such a problem. The
bugs stay in the pool. But to make a good cloud safely you'd somehow need to
maximise the surface area of the water without any splashing. On a larger
scale, power station cooling towers are designed to do exactly what you
need. They sprinkle the warm water down through warmed, rising air, but they
have to take precautions against Legionella. Do you really want to go there?

My abiding memory of an October visit to New York is the amazing white
clouds billowing up from warm sewers at every street intersection.

I'd only attempt it as a winter feature.

Won't it require a LOT of heat to cause the cloud to rise fast enough? In my
mind's eye, I'm just seeing the cloud hanging there. And if it needs a LOT
of heat, shouldn't it be some form of recycled waste heat, to avoid
environmental criticism? Hey, maybe this should be a mass-produced
sculpture, built into New York sewer covers... (Or a huge version, above a
power-station cooling tower...!)

Indoor tornado exhibits are very sensitive to small draughts and any kind of
turbulence. However well-sheltered, the surrounding structure will need to
be designed quite differently, so that varying winds cause the air inside it
to rotate smoothly. Tricky! Prototyping experiments could be done with a
smoky fire.

If successful, children will certainly interact with it very
enthusiastically and physically. A slotted GLASS structure, you say...

I'd also consider forgetting the vortex and just make it into a very
appealing 'cloud' sculpture instead...

...Or feed the cloud into a giant smoke-ring cannon? Maybe that's a more
practical idea?

[log in to unmask] * http://www.interactives.co.uk
*
Give people facts and you feed their minds for an hour.
Awaken curiosity and they feed their own minds for a lifetime.
*
Ian Russell

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