Evolving Thoughts


Tuesday, March 21, 2006

Making ball lightning

When I was a kid, I used to go lie in the rain on the roof and watch the lightning. Hey, it was better than fireworks, free, and delivered to your door. What can I say?

One night I saw the most amazing thing - I was about 11 or 12. A glowing ball of light about 50 feet up (this was before they allowed meters into Australia) which was about half a meter across (OK, I give in) moved slowly through the air, silently, and leaving a trail behind it that faded rapidly. "Cool!" I thought, and wondered if I could essay this as a UFO experience to my friends. UFOs were so the rage back then...

It was, of course, ball lightning, although at that time physicists denied such a thing could exist. Now they don't, but it's a hard thing to explain. Which is why this research is so interesting.

A team at Tel Aviv have created ball lightning in the lab.
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.

It's pretty cool, but not a spot on my ball lightning. Still, interesting stuff going on with this lightning research, what with "sprites" and "elves" and "jets" and wotnot. It seems there's more to it than Ben Franklin knew...