Cause of ball lightning
Ball lightning is one of the few phenomena that are widely accepted
in the popular and scientific community as being real, although none
of the many theories can fully explain all reports of people who
observed ball lightning.
The more 'successful' theories explain ball lightning as being
caused either by glowing carbon fibres, 'maser' of the air
(microwave amplification), gas discharges and such. Probably
there are several different kinds of ball lightning that can be
caused by different mechanisms. Whatever its cause, ball
lightning is quite rare and very exciting to witness, if you are
interested in lightning and thunderstorms.
Ball lightning is mostly witnessed as being a spherical glowing
ball usually a few centimeters or inches in diameter, similar in
brightness to a 100-Watt light bulb. It may exist several seconds,
drift through the air, drift through glass panes or be connected
to a metal structure, and it may end silently or explosively.
Ball lightning is said to occur mostly during active thunderstorms,
and many reports seem to come from relatively flat areas (not
mountainous). Almost every storm may produce ball lightning but
they are rarely seen.
Photographing ball lightning
I have never seen a photograph that clearly shows ball lightning.
Many if not most photos I have seen either show streaked photos
from artificial light sources or powerline failures (sparks or
fireballs originating from powerline transformers and such). Other
photos possibly show ball lightning but very far away.
The best tactic to have any chance to document ball lightning is
to have a digital camera ready to use at all times during a
thunderstorm. That camera must have a lens attached and be turned
on. But even that tactic may not work. The only possible ball
lightning I have seen existed so shortly that I didn't even have
time to grab my camera, even though it was ready to take pictures.
A photo that shows a streaked light purportedly
being ball lightning often turns out to be fake. There is even more
reason to be suspicious when the photographer didn't see anything unusual during the exposure.
Some possible causes for fake ball lightning photos
As said above, most photos that purportedly show ball lightning
are either faked or accidentally show something else. Some
possibilities for misidentification of ball lightning are:
- powerline faults, usually in the form of sparks or plasma arcs
at transformers ('pole pigs' as they are called in the USA).
- photos of lightning while the tripod-mounted camera was bumped
during the time exposure. Even though the lightning may not be
blurred, because the bumping of the camera could have occurred before
or after the flash, any foreground light such as a streetlight will
show curious tracks along the photo with a bright ball of light at
one end (the location where the streetlight appeared during most of
the time exposure).
- fireflies that fly through the camera view; since they light
up only briefly, they will show a short track of light in the frame.
- fireworks and flares.
- glowing sparks that jump away from the contact point of lightning with ground the instant