An observation of synthetic ball lightning

Ball lightning has been extensively researched for many centuries. Here, in this paper, we present one form of ball lightning where plasma spheres several centimeters in diameter were produced in atmospheric pressure air. These spheres persisted for up to a half second after the power supply was turned off. A mathematical theory was derived that predicts the observed lifetime. The theory predicts that the sphere lifetime should scale as the sphere radius squared, which means that large spheres should persist for many seconds.