Ball Lightning

[ramsrc]

I realise the topic of lightning strikes on aircraft has been covered before but I have a more specific question.

Whilst listening to the local news on the radio this morning, I heard an interview with a passenger who was on a Lufthansa flight yesterday, flying over the Vogelsberg mountains. Unfortunately, although the flight number was mentioned I was not awake enough to remember it!

Apparantly, the aircraft was struck by lightning. (Not surprising given the number of thunderstorms around here yesterday.) The entire cabin was illuminated with a blue glow from outside, and a large ball of bluish light rolled down the aisle of the aircraft before dissipating towards the back and leaving a faint haze of smoke.

Which brings me onto my question. I realise that ball lightning is rare and there is very little known about what causes it, but has anybody seen this phenomena?

[5150]

Never seen it myself, but a friend has when flying in close proximity to a thunderstorm. It's apparently caused by the increased build up in static electricity approaching a TS as well as the speed and friction of the aircraft as it cuts through the air.

Otherwise known as St.Elmo's Fire, it's not dissimilar to those lightning-type ball's they still sell in gadget shops, where you can track the lightning across the glass with the tip of your finger......

That's about as technical as my understanding goes......!

[Capt. Crosswind]

I believe Qantas had a similar incident in the 1960's.
In this case the "ball" drifted down the aisle & contacted a steward giving him an electric shock.
Acft was a B707. Perhaps a Qantas Pruner can dig up the details?
I understand the phenomena of ball lightning is still not fully undrestood.

[McD]

Here's some more info on Ball Lightning, St. Elmo's Fire, and the differences between the two (separate but likely related) phenomena:

Excerpts From Scientific American: (see this link (http://www.sciam.com/askexpert_question.cfm?articleID=000CB330-61BF-1C71-9EB7809EC588F2D7&catID=3&topicID=13) for complete articles)

"St. Elmo's fire is sometimes mistaken for ball lightning...St. Elmo's fire is an example of a continuous corona discharge. It is not a form of lightning."

Apparently, St. Elmo's fire must remain attached to a conductor, while Ball Lightning is unattached. For instance, on an aircraft, St. Elmo's fire will be seen emerging from a point or points on the nose and racing up the windscreen, while ball lightning might be seen floating from the front to the back of the aircraft.

Another difference (based on anecdotal evidence) seems to be that ball lightning witnessed on aircraft occurs after a strong static discharge or lightning strike. St. Elmo's fire may occur simply when flying through heavily-charged skies (i.e. in an area where thunderstorms are nearby, but not necessarily close enough to be struck by lightning).

You can click here (http://www.sciam.com/askexpert_question.cfm?articleID=000CC3F9-66E4-1C71-9EB7809EC588F2D7&catID=3&topicID=13) for another article (from the same publication) regarding Ball Lightning.

[canberra]

i remember my parents telling me about the lightning they saw dancing down the street(that was how they described it)! it was from a lightning conductor on the church opposite, they reckoned it was one of the greatest things theyve ever seen. apparently it went on for about 10 minutes.

[ramsrc]

Thanks very much, everyone.


Scientific American articles in particular very interesting.

[Big Tudor]

I can well remember the first and only time I ever witnessed this phenomena. As a young, green behind the ears servant in HM forces, I was lucky enough to scrounge a fam flight on a Nimrod. Somewhere north of the Shetlands, I was summoned to the flight deck to witness a 2 foot diameter ball of light on the end of the refuelling probe. To say I was mesmarised would be an understatement. I regretted the fact that I did not have a camera with me but, with hindsight, I realise now that no picture would have done the sight justice. It really does make one feel very small and humble in the face of Mother Nature.

[Flap 5]

It is very common to get St Elmos fire on the windscreen as the heating elements make it a good conductor.

The most I have ever been stuck by lightning is in an A330, with no ill effects. A bit of a worry in an electric aeroplane! On one occasion the nose wheel doors opened and closed suddenly but fortunately we were descending below 10,000feet and so our speed was below 250kts, or they would have been ripped off!

[snichols]

There have been various research programmes into ball lightning, mostly in the US. One theory is that it is a ball of plasma - an extremely hot collection of electrons and protons with so much energy that the atoms remain ripped apart. This would give it the characteristic blue colour, but doesn't really explain how it hangs together or why it floats around for ages.

Another theory (US-based Robert Golka) is that ball lightning is caused when a massive electrical discharge to earth melts small pieces of metal and superheats them to incredibly high temperatures. The outgassing would cause them to dance around until they cool sufficiently. I have seen a video of someone who has tried to recreate i but it wasn't convincing.

Another company has tried to recreate ball lightning in microwave ovens with some success, but these operate on high frequency. The thought is that this is something to do with vapourised/ionised carbon. These could be causes after a lightning strike to a tree or carbon fibre.

I think the jury is still out!