Let's just make this clear from the get go: we know little to nothing about this phenomenon. In fact, for many years ball lightning was thought to be something made-up or misinterpreted by eye witnesses. Through the rapid increase in photographic and video technology, we've added many more cameras to the world and through these observations scientists have begun to acknowledge that ball lightning exists... but now the real questions arise: what is it, and how does it form?
So we'll start with the basics. Regular lightning itself is still quite an enigma to researchers, but at least we feel we're beginning to grasp the foundations of how it's created. It's generally accepted that as a thunderstorm begins to form from a rapidly rising current of air (updraft), the water droplets eventually reach the freezing level where ice begins to form. Scientists now believe it's the interaction between ice and water in a thunderstorm where electrical charges are exchanged and eventually dispersed into the cloud. In the most basic sense, most storms gather a positive charge at the top of the cloud while a negative charge forms at the base. Knowing that opposite charges are attracted to each other, the negative charge at the bottom of the storm induces the ground below it into a positive charge. If the storm eventually builds up enough of a charge, the energy is released as a lightning bolt from the cloud to the ground. Remember how we just talked about the negative and positive charge in the cloud itself? This difference can also create a lightning bolt within the cloud. In fact, most lightning bolts are intracloud lightning roughly 75%-80% of the lightning a cloud produces.Lightning strike panorama over Bucharest, Romania on June 26th, 2007 by Catalin.Fatu at en.wikipedia Lightning captured by Raul Heinrich striking the CN Tower in Toronto July, 23rd 2008
That's basically how lightning forms, so what about "ball lightning"?
Since the dawn of man, people have given many descriptions of ball lightning. Most accounts talk about the sight of a glowing ball of light (about the brightness of a 100 watt bulb) anywhere from the size of a tennis ball, to the size of a beach ball. Almost all accounts talk about seeing some sort of glowing ball in the air. Sometimes reports have the ball dropping towards the ground and moving around very quickly and erratically. Some people say the ball travelled from outside to inside a house or building through and open door or window, sometimes scorching the floors and walls on its way before it vanishes. Other stories tell tales of the lightning balls fusing metal together, disrupting electrical wiring and/or equipment, and even scorching or killing people! Ball lightning accounts range from people experiencing highly electrical thunderstorms, to others saying the ball burst out of "thin air" from a gentle rain on a cloudy/cool day.
The leading theories around ball lightning all eventually point to the formation of something called "plasma". Plasma is something thrown around in all sorts of science-fiction books and films, but it is a real thing - most recently associated with flat screen televisions. Plasma (as defined by dictionary.com) is "a highly ionized gas containing an approximately equal number of positive ions and electrons."
Let's look at something you're probably a bit more familiar. You've seen one of these, right?Photo courtesy: Luc Viatour / www.Lucnix.be
I like to sum up the notion of plasma as electrified gas/air that acts more like a fluid. Now imagine taking the "electrical strands" you see in the toy plasma lamp, scrunch them up into a ball and that's pretty much what experts believe to be ball lightning.
So imagine that you're just minding your business, when all of a sudden you see a bright flash, hear a tremendous boom, then see a glowing ball in the air! I find ball lightning so interesting because it's seems to be a phenomenon that people rarely even think about, and when it does occur it's a complete surprise!
Ball lightning stories even have a local flavor. Our own chief meteorologist Doug Hill has a family account of witnessing a ball lightning event! According to his mother and her brothers and sisters, when living just right off the Inner Harbor in Baltimore a lightning ball came right through a wooden framed screen door in the front of the narrow, shotgun style home, travelled down the wooden floor leaving scorch marks in its wake, before exiting through the back screen door!
Through researching this topic, I found a great website that has an extensive log of personal ball lightning accounts: http://amasci.com/weird/unusual/bl.html There also happens to be a really cool case study that was performed on a ball lightning account in Queensland, Australia back in 2002. Here's a link to their page:
Lucky for us, a photographer caught the event! Here aresome of his photos:Courtesy of: ERN Mainka Courtesy of: ERN Mainka Courtesy of: ERN Mainka