Thursday, January 11, 2007

Dancing Ball Lightnings in the Lab

Ball lightnings are mysterious things: Small, bright balls of fire suddenly appear during a thunderstorm, swirl around, make sometimes funny noises, and leave behind a smell of ozone. My grandmother has often told me how she once has witnessed one when she was a little girl.


The sudden appearance of a ball lightning can be quite frightening. (Hergé: The Seven Crystal Balls)


In the Tintin adventure The Seven Crystal Balls, a ball lightning destroys the mummy of an ancient Inca King which was brought to Europe by seven explorers, all of whom succumb to a mysterious spell and fall into a deep sleep interrupted only by cruel nightmares.

Since ball lightnings are not only spooky, but also very elusive, there has been a lot of speculation how to understand and explain them in a scientific way: People have suggested that it may be some ionised balls of plasma held together by their own magnetic fields, or even such exotic things as mini black holes leftover from the big bang...

A more "down to Earth" explanation was proposed in a 1999 Letter to Nature: John Abrahamson and James Dinniss conjectured that a ball lightning may be caused by the burning of small particles created when a normal lightning strikes on soil. The stroke of the lightning would vaporise and reduce silica in the soil into pure silicon vapour. As this vapour cools, they suggested, the silicon condenses into a floating aerosol bound by electric charges on its surface and forming some kind of bubble. Like the magnesium in the flashlight of an old-fashioned photographer, the pure silicon immediately burns in the oxygen of the surrounding air. This then creates the bright light and the smell of the ball lightning phenomenon, which then would be not an electric discharge, but a chemical reaction.

The explanation proposed by Abrahamson and Dinniss has now been tested by by a group of chemists and physicists of the Universidade Federal de Pernambuco in Recife, Brazil, as reported in the New Scientist. The paper Production of ball-lightning-like luminous balls by electrical discharges in silicon by Gerson Silva Paiva, Antonio Carlos Pavao, Elder Alpes de Vasconcelos, Jr. Mendes Odim, and Jr. Felisberto da Silver Eronides has been accepted for publication in PRL in January 2007. In their experiment, the Brazilian scientists vaporised parts of silicon wafers by the application of high currents of up to 140 Ampere. In the electrical arc of this discharge, similar to a lightning hitting soil, small glowing fragments of silicon could be created, and, sometimes, Ping-Pong ball sized blobs persisting for several seconds!


Small balls of burning silicon vapour dancing on the floor (Espacociencia, Olinda, Brazil, mpg file)


There is a small movie available which shows little balls of light, burning silicon vapour dancing on the floor of the laboratory (unfortunately, the movie does not seem to work with Mac...). These small little things probably wouldn't frighten good old Captain Haddock, but they are quite impressive, nevertheless.

Even if it's not completely clear yet if the riddle of the ball lightning is solved, as claims a headline in the German news magazine Spiegel - this Brazilian experiment may bring us closer to 'home made' ball lightnings as a fancy show effect for the next cocktail party!



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15 comments:

Bee said...

The movie didn't work with IE either, I had to download it and save it on the desktop. After this, realplayer and the Windows media player worked fine. Great post btw, I love the Hergé comics, esp. Captain Haddock, he's so eloquent ;-)

Arun said...

Fellow Tintin fans!

:)

Re: ball lightning, I suppose the report of ball lightning floating down the aisle of a plane must be a mistaken one.

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CarlBrannen said...

arun,

The chemistry of aluminum and silicon might similar enough that the same effect could occur...

But there are a bunch of other observations that I think are incompatible with this.

QUASAR9 said...

Interesting, what got you thinking about this topic? synchro-ni-city
We still don't know exactly how lightning volts are 'formed'
and speculation on ball lightning continues ...

Common Bee, you can do it
There's gotta be room there for neutrinos to make a 'guest' appearance

Bee said...

Hey Superfake,

The meme reached us shortly before Christmas, the post is here. I was tagged by Clifford from Asymptotia. I left a comment on your blog as well... sorry, I don't speak Italian! Best,

B.

Bee said...

Hi Arun,

the report of ball lightning floating down the aisle of a plane must be a mistaken one.

They really should work on the quality of in-flight meals...


Hi Carl,

But there are a bunch of other observations that I think are incompatible with this.

Yeah, that's what I thought as well. But then, I kind of suspect that all what people have called 'ball lightnings' might actually have been very different phenomena, ranging from LSD afterglows, over aliens levitating in the air to dancing silicon...

Best,

B.

Bee said...

Hi Quasar,

speculation on ball lightning continues ...

Common Bee, you can do it
There's gotta be room there for neutrinos to make a 'guest' appearance


Sorry to disappoint you, but for me there's too little data for educated guesses. I actually find the myths around ball lightnings far more interesting, they tell a lot about the 'modern' civilization's capacity to cope with the unexplained.

Best,

B.

Charles T said...

Well this week's New Scientist sounds a good deal more credible than last week's New Scientist where they published an article about ball lightning being created by primordial black holes (which don't evaporate by Hawking radiation after all).

Rae Ann said...

I've never seen ball lightning, but it sounds pretty cool. But if they can create it in a lab, won't it soon be turned into some kind of weapon?

funny word ver.: uygunm

stefan said...

Hi Charles T,

indeed, I was a bit cautious when I read "New Scientist writes that Ball Lightning was created in the Lab", with all the sensationalist and often outright cranky stuff they report lately. OK, but then, I checked that this really some research with a paper accepted at the PRL, so I thought that the story probably should be taken serious ;-)


Dear Bee,

what people have called 'ball lightnings' might actually have been very different phenomena

oh, that's a very good point... may be right...



Dear RaeAnn,

won't it soon be turned into some kind of weapon?

hm, it has been turned in a waepon - at least in the Tintin adventure ;-)

The problem (or good thing, in this case) is that most probably, you won't have haardly any influence as to where this ball is moving... As in the movie, where all the small lightning balls zip around completely erraticly...

Nice Weekend to all,

Stefan

CarlBrannen said...

Stefan, I was not impressed with the video I saw. They were heavier than air. I've seen quite similar things while arc welding and especially while cutting with an oxygen torch.

Bee said...

Hi Carl,

I too wasn't impressed by the video. It reminds me of the liquid oxygen that we used to fool around with. It behaves quite similar if you drop it to the ground. It begins to boil immediately, and fuzzes around randomly, much like a drop of water on a hot plate. Best,

B.

Wizard Bill said...

This is clearly NOT ball lightning; it is much heavier than air and is obviously has burning solid at the core. The theory cannot be correct as BL forms frequently far from the ground, cannot be contained by electrostatic fields, and high energy BL is many orders of magnitude too energetic. Plus low energy BL can go through glass. I am doing BL research at NCSU, you may see my work at billrobinsonmusic.com.

Bee said...

Dear Wizard,

This is clearly NOT ball lightning

Well, you might have missed what I wrote above. The question is what do people actually mean with 'ball lightening'? As far as I can see it's a ball and its somewhat bright, so its something like a lightning ball. All the points that you have mentioned seem to indicate you have a more precise characterization in mind. What is it based on. Actual observations? Told stories? I couldn't find more info on your website. Best,

B.