Ball lightning over the water surface

Numerous reports of ball lightning (over the past three centuries, more than 2,000 reports have been received) are contradictory: observations describe mainly balls of yellowish to reddish color with a diameter of up to 20 centimeters. Their appearance is often associated with a lightning strike during a thunderstorm. They last from seconds to minutes and disappear quietly or with a bang. They move slowly, sometimes noiselessly, sometimes with a hiss, but also stop and supposedly penetrate the walls.


There is no direct data, and available photos may also show comets, meteors, or fireworks. Attempts to explain assign a key role to electric and magnetic fields or chemical energy. There has also been talk of magnetic stimulation of the brain or retina. In 2014, Chinese scientists engaged in the study of lightning during thunderstorms accidentally observed a phenomenon resembling descriptions of ball lightning.

Attempts to explain assign a key role to electric and magnetic fields or chemical energy. There has also been talk of magnetic stimulation of the brain or retina. Laboratory studies all over the world point, for example, to microwave discharges, electric arcs or electric discharges in water as causes.

Ball Lightning experiment in IFP

At the Institute of Plasma Physics named after Max Planck in Garching and Greifswald spherical objects called plasmoids are created above the water surface by an electric discharge. The experiment is based on the Russian concept, which received a scientific continuation in the former Berlin laboratory of the IPP, where plasma diagnostic methods were used. At the end of 2009, the installation was moved to IPP Garching and redesigned. Currently, research is focused on plasmochemical processes, which probably serve as a source of energy for the plasmoid and, thus, determine its lifetime.

The experimental setup consists of an acrylic glass bucket filled with water, in which two electrodes are installed: a copper electrode at the bottom and a thick wire — the central electrode — on the surface of the water. A ceramic sleeve around the central electrode separates a small water tank from the rest of the water. Using a switch between the electrodes, a high voltage of up to 4.8 kV can be applied. The voltage comes from a capacitor bank, which is charged from a high voltage source.

When the switch is activated, a strong electric current from 50 to 130 amperes passes through the water for about 150 milliseconds: a glowing plasma ball rises above the central electrode from the surface of the water, which exists for about 0.5 seconds. 

A more thorough analysis shows that out of 10 liters of water in a bucket, about 10 milligrams evaporates and ionizes. The plasmid carries an energy of about 4 kJ. The lifetime is highly dependent on the amount of energy.

Observation using a high-speed camera shows the initial formation of a surface discharge with filamentous structures before the plasmoid acquires its spherical shape. Due to the plasma temperature of about 4000 kelvin, it turns into a mushroom-like structure typical of an ascending hot gas. The temperature is also sufficient to produce an intense glow, exciting the atoms and molecules of water and the minerals contained in it. Therefore, the color and intensity of the glow can be changed by adding various salts to the water.

Around the hot ball, the colder edge area forms the skin. Thus, a piece of paper placed in the path of plasmoids is not affected. The plasmoid deforms and goes out, but does not penetrate the paper — unlike what is reported about ball lightning.