PureInsight | January 6, 2001
IGHTNING MAY BE THOUGHT OF as a huge, sudden spark of electricity generated by the difference in electricity between particles of matter ¡ªfor example, between opposite charges within two clouds. The discharge follows the line of least resistance, which often forms a forked pattern. In addition to
normal fork lightning, however, thousands of people in the United States and Europe claim to have seen luminous spheres moving through the air during or after thunderstorms ¡ª so-called ball lightning.
Ball lightning may be white, orange, blue, or red, and is said to vary enormously in size, from grape to basketball. Such lightning is often accompanied by a loud.
hissing sound. Some eyewitnesses claim that ball lightning is capable of passing through walls and moving against the wind. According to some accounts, it can cause damage by burning or melting various materials; others maintain that it is quite harmless. It reportedly dies out suddenly, eithersilently or explosively, a few seconds after it first appears.
Unlike normal lightning, ball lightning appears to occur without any apparent contact between oppositely charged particles, thus defying ordinary physical principles. Its occurrence is therefore much more difficult to explain. Many scientists used to dismiss ball lightning as an illusion. For example, in 1839 the British physicist Michael Faraday (1791¡ª 1867), whose experiments form much of the foundation for our understanding of the forces of electricity and magnetism,
theorized that ball lightning might simply be an after-image formed by the human eye following initial exposure to the flash of ordinary fork lightning.
But the Soviet scientist Pyotr Kapitsa, winner of the Nobel Prize for physics in 1978, disagreed. He suggested that ball lightning was indeed a true, physical phenomenon. He proposed that the luminous globes consisted of plasma matter composed of electrically charged atomic particles stimulated by natural radio waves to generate light. Recent experiments by two Japanese physicists appear to support this view. Some experts, however, are still not convinced and maintain that the precise nature of ball lightning remains unexplained.
The Japanese experiments
In 1989, Yoshi-hiko Ohtsuki of Waseda University and H. Ofuruton of Tokyo Metropolitan College of Aeronautical Engineering reported that they had created ball lightning in the laboratory. Using a magnetron (a generator of microwave radiation) connected by a special guide wire to a copper cavity, they were able to create small regions of concentrated energy within the cavity. The experiments yielded different types of balls of varying colors. One type of ball occurred only rarely throughout the experiments; the scientists suggested that this might be a plasma vortex.
Following the revelations of the Japanese scientists, Dr. Stanley Singer, chairman of the International Committee for Ball Lightning Research, announced that their experiments ¡°were a considerable advance over any previous studies.¡± However, if ball lightning does consist of plasma, as many scientists now believe, further work is needed to identify the forces that hold it in a sphere.