Below are photos and details on our attempt to create "Ball Lightning"

Five capacitors were connected in parallel.  Each capacitor had the following capacity:  800 uF,  5000 V,  160 lbs, 10,000 J energy. 

In total, all five capacitors in parallel equaled: 4000 uF, 5000 V, 800 lbs, 50,000 J energy.

A high current / high voltage switch (not shown) was used to connect the capacitors to the load.  The high voltage switch consisted of  spring loaded arm with brass balls as the contacts. 

The ball lightning is created at the electrodes which are in a bucket of water. 

Ground Electrode.   The ground electrode is a copper shaped ring at the bottom of the bucket.   

Positive Electrode.   The positive electrode has bends in such a way that it loops over the edge of the bucket, down into the water and then pokes out at the surface in the center of the bucket.  Only a 1/4" diameter by 1/8" long section of metal pokes out of the surface of the water.  This electrode  is mostly insulated with silicone tape except for the exposed tip at the surface of the water in the center.

The five capacitors were charged up to 3000 Volts (lower than the 5000 V capacity) and the high voltage switch was triggered by pulling on a piece of fishing line.  The following images and videos were captured.  

The water is normal tap water.  During the capacitive discharge, a small mushroom cloud erupts from the surface of the water.  In the photos and in the video with the black background, you can see the mushroom cloud dissolves into a big green afterglow for a split second.  Oxygen emission lines account for the green color.

Click on the photos below for a larger image (photos captured from the video).

Small mushroom cloud created during a capacitive discharge .

Capacitive Discharge giving a "green" afterglow.