Can you create lightening with water, plastic, and metal? That's exactly what Bram Van Cleave, Erik Maddocks, and Jennifer Brown did by constructing Kelvin's Thunderstorm for a class project (PH431, Electricity & Magnetism). The Thunderstorm uses water to build an excess of equal but opposite charges on two nearby spheres. When the potential difference between the spheres is large enough, a spark will form to eliminate the excess positive and negative charges.
Erik Maddocks discusses why the Kelvin Thunderstorm's geometry is important.
Jennifer Brown discusses the dissociation of H2O molecules into ions.
Bram, Jen, and Erik successfully constructed the Kelvin Thunderstorm as a class project.
Retired medical doctor Frank Hieber (who sat in on PH431) examines the lower portion of the Kelvin apparatus (the upper portion is not shown in the photo).
Look closely at the two spheres - you will see a lightning bolt!
Here is a closer view... See it?! As you can imagine, the experiment works especially well in the dark.