Charge Sheath Vortex: A minature tornado in the laboratory
This tornado is in a sealed plastic petri dish.
With no external sources driving the movement of air or particles inside the container, the vortex forms entirely as the result of the electrical discharge.
The dark areas on the picture are the tape holding the dish in place.
A large Van de Graf generator is connected to terminals (drawing pins) through the top and botton edges of the container.
The dust in the container is standard table salt! (tesco own brand, notiodised)
The sequence was filmed with a hi8 video recorder. These are successive frames, unedited in any way other than conversion to jpg.
Above, tornado starts to form
Below, Note that the elctrical discharge does not flow through the dust tornadobut appears to be repelled by the tornado
Below - dust tornado continues after electrical discharge
Below- but one frame later the tornado has now collapsed.