Aaron
Ball lightning
I have never seen it but it is an interesting topic. It is explained in my book "Extreme Weather". Up until 2007, it is a phenomena that has not been videotaped, positively photograped or otherwise recorded scientifically in the natural world.
Attempts at reproducing ball lightning in laboratory simulations have been successful.
Lightning balls range in size from from less than 2.5 cm across to over 1.8 metres in diameter but they average 10 cm to 60 cm range with most reports referring to "basketball size". The duration of the observations ranged from less than one second to over two minutes but average 1 to 4 seconds. The colour has been described as white, red, orange,, yellow, green, blue, violet or a mix of several of these colours. The most common colour reported is white, yellow or orange.
The balls dissipate with an explosive bang or alternatively they may silently fade away. They have been observed to rotate, roll or even bounce off the ground but they usually move slowly and in a horizontal direction. They can penetrate steel screens, glass windows and small holes. Some observations have reported the balls making a hissing, buzzing or fluttering sound and leaving an acrid odour.
The intensity of lightning balls is not great being the brightness of a 60 Watt light bulb. In almost all cases, the balls maintain the same shape, size, colour and motion during their short life time.
Lightning balls have been known to hit people causing a burn or singe mark but there are no known human fatalities.
How they occur:
The balls are almost always observed seconds after a nearby cloud to ground lightning strike of ordinary lightning Theories as to what causes the formation of ball lightning includes one that postulates the balls have an internal energy source, probably particles ejected from the Earth when a normal lightning strike hits then somehow becomes electrified and airborne. A person called Abrahamson and J Dinnis has a theory and suggests that silicon nano particles evaporated from sand by the lightning strike forms a ball and by their oxidation illuminates the ball.
Rakov and Uman (University of Florida has concluded that there may be more than one type of ball lightning and more than one mechanism that creates it. Similar phenomena has been known to occur from high powered electrical appliances in the absence of nearby thunderstorms.
There are very few photographs floating around of ball lightning but there is one which is in my book showing ball lightning close to a power pole taken in Japan. Generally photographs of it is very rare.
Taken from (Extreme Weather - Thunderstorms and hail) Christopher C Burt 2007).
Harley Pearman
