By Ker Than
LiveScience Staff Writer
posted: 23 February 2006
08:56 am ET
Artificial ball light
Ball lightning is one of the most mysterious phenomena in nature. Now scientists have created a laboratory version of the eerie floating orbs using technology taken from a common microwave oven.
The work could help scientists figure out how the lightning forms in nature and lead to practical applications that harness its power.
In the wild, the little bundles of energy are typically only a few centimeters across, although some have been reported to be the size of beach balls or larger. They are closely associated with regular lightning and thunderstorms and have been seen in many different colors.
Witnesses report hissing sounds and an acrid ozone odor when the lightning balls appear. The vivid apparitions normally hover or float around for only a few seconds before vanishing suddenly, either silently or with an explosive bang.
Although people have known about ball lightning for centuries, scientists have yet to come up with an explanation that accounts for all of the strange properties.
Eli Jerby and Vladimir Dikhtyar from the University of Tel Aviv in Israel created a laboratory version of ball lightning using a "microwave drill." The device consists of a 600-watt magnetron taken from a domestic microwave oven and uses a powerful microwave beam to bore through solid objects.
The researchers aimed the beam through a pointed rod and into a solid object made from glass, silicon and other materials.
The energy from the drill created a molten hot spot in the solid object; when the drill was pulled away, it dragged some of the superheated material along with it, creating a fire column [video] that then collapsed into a bright fireball that floated and bounced [video] across the ceiling of the metal enclosure.
"The fireball [looked] like a hot jellyfish, quivering and buoyant in the air," Jerby said.
The glowing object measured just slightly over an inch across and lasted only about 10 milliseconds. The work was detailed earlier this month in the journal Physical Review Letters.
The composition of the laboratory lightning ball still needs to be verified, but it appeared to resemble those found in nature.
"Our experiment confirms to some extent the theory that ball lightning originates from hot spots in the ground created by normal lightning," Jerby told LiveScience.
According to one popular theory, ball lightning forms when lightning strikes the ground and vaporizes mineral grains in the soil. The vaporized nanoparticles could then link together into chains and form a fluffy ball of silicon that floats on the wind. The particles react with oxygen in the air and release light as they burn.
Jerby thinks that his laboratory lightning balls could one day find practical uses in industry.
"My imagination leads me to speculate on applications like 'bulb-less' light sources, coating and deposition or energy production," he said.