Dec 8, 2006
Sequence of photographs showing initial arc and formation of stable fireball.
Texas State University-San Marcos engineering professor Karl Stephan conducted an experiment designed to help decipher the enigmatic nature of ball lightning, research that yielded a publication in the journal Physical Review E.
Stephan's interest in crafting this experiment sparked when he read about researchers in Tel Aviv University who were able to create objects with the same characteristics as ball lightning. He worked in conjunction with University of Texas at Austin professor John A. Pearce, who also directs the Process Energetics Laboratory at UT's Pickle Research Campus.
Ball lightning differs from ordinary lightning in that it takes the form of a glowing ball that ranges in size from a softball to a beach ball and it lasts several seconds or more. This phenomenon of nature is often sighted with thunderstorms and has the ability to hover, float down chimneys, pass through closed windows and either disappear in silence or in a sudden explosion.
Stephan found that he could produce the "fireballs" by touching two tungsten welding rods together and drawing them apart with microwave power applied to the system. When the rods are moved apart, the effect produces a fireball that persists as long as the microwave power is applied and disappears when the energy source is shut off. The importance of this experiment is that it can explore the conditions needed for a ball-lightning object to exist in the air, thus contributing to the understanding of this mysterious phenomenon.
The paper describing Stephan's research was published in the November 2006 issue of Physical Review E and is posted on the American Physical Society's website at http://link.aps.org/abstract/PRE/v74/e055401. Two movies depicting the fireballs can be accessed by clicking on the note in the paper's Reference 11 (http://netserver.aip.org/cgi-bin/epaps?ID=E-PLEEE8-74-R02612) and following instructions. For additional information, contact Karl D. Stephan of the Department of Engineering and Technology at Texas State University-San Marcos