Note injury on 3rd finger. Bright area to right is arcing and can be ignored. The blue light around the fingertips is a photograph of the electrical discharges due to the conductivity of high voltage, high frequency electricity, by living things. Metals and semi-conductors also produce discharges. A non-conducting, dry object, such as a piece of cardboard will not produce any discharge.
Humans are sort of a walking semi-conductor.
We are full of electrolytes that travel specific paths in our bodies, and because of this, the corona naturally discharges from the terminating points of those paths. A good example of this is a leaf. When you oberve a discharge from a leaf, the corona eminates from the veins of the leaf, the bulk of which can be seen emerging from the ends of those veins around the edge of the leaf. I will soon be displaying leaf and other specimens subjected to coronal discharge . I have heard of people who claim to be able to diagnose ilnesses using coronal discharge observations.