Wednesday, September 23, 2009

Probably not ball lightning

On September 20, 2009, at around 15:36 MDT, I was driving north on I-25, somewhere around the first five miles north of the northernmost Belen exit, in a hard rain in the middle of an electrical storm. My speed was somewhere over 60 mph. I saw what looked like a direct lightning hit on one of the utility poles paralleling the freeway on the east side, a fraction of a mile ahead of me. I was concentrating on the road, since the rain was coming down hard enough that I was using the faster windshield wiper speed, traffic was somewhat heavy, and visibility was not very good.


A very short time after the lightning hit, my attention was attracted to a bright light in the direction of the pole that had just been hit. At first it resembled a reflection of the sun, as when a highway sign is hit by a low-angle sunbeam and reflects it completely. However, that wouldn't explain it; the sky was completely overcast and there were no holes where the sun might have gotten through.


As I approached the impact site, it became apparent that the source of the light was at about the same distance east of the freeway as the utility wires. The light was a brilliant blue-white color, and it didn't seem to be a point source. It looked sort of amoeba-like, although the windshield didn't really give me a clear view. It was not at a pole, but about a third of the distance between the nearest pole and the one just south of it.


As I passed even with the site of the light, it seemed to me that it was not a point source at all, but an irregular blob of brilliant light at least a few feet in diameter, judging the distance by parallax. Its angular size was perhaps half the size of my fist held at arm's length.


Wrenching my attention back to the road, I had a strong afterimage, as when one inadvertently looks at the sun. I was a little concerned that I might have burnt my retina, but the afterimage faded within a minute or so. I checked both my rear-view mirrors as soon as I could spare the attention, but did not see a strong light in either mirror. The duration of the light was at least five seconds, perhaps as much as ten.




Analysis


New Mexico Tech is well-supplied with weather researchers, and I asked some of them about this. I was wondering if it were ball lightning. Here is a reply from Dr. Harald Edens:


I've seen a handful of reports and even a photo from alleged ball lightning in The Netherlands when I still lived there, that were caused by lightning-induced arc-over between tramway or railway overhead power lines that are everywhere in the cities over there. It made me very skeptical of ball lightning reports that have to do with power or phone lines.

As far as I know, many ball-lightning reports that cannot be explained by other means (including my own observation several years ago) are of some phenomenon that is not necessarily attached to anything. It also apparently is not all that bright (about the brightness of a 100W bulb), while plasma arcs on power lines can be blinding. Perhaps the arc looked big and spherical because it was scattering light through microscopic dust on your windshield, or it happened to be larger than the wire separation due to convection of the plasma arc that makes it bend upward into an inverted 'U' shape. I myself find anything that is extremely bright difficult to distinguish in shape, and appears round.

This is only my opinion, and ball lightning or not, I find it an interesting observation of yours!

It seems that based on the surface brightness alone, my observation was of a simple arc and not ball lightning. And there was a lot more than dust on my windshield at the time—it was a heavy, driving rain.

If you are reading this and have any other thoughts on what may have caused it, please leave a comment or send e-mail to john@nmt.edu.

1 comment:

Tony Perreault said...

It was probably ball lightning.

My mother would tell of how ball lightning would frequently play a visit at the home where she grew up. Part of the property had the large metal high voltage transmission lines that were near the house. Every time there was a bad thunderstorm ball lightning would appear in the house. It started at the door to the outside (in the kitchen), float through the kitchen, make a 90 deg. turn to the right into the living room, float through the living room, make another 90 deg. turn to the left and go through the wall. Once would have been freaky enough, but she said that it happened every time there was a thunderstorm over the power lines / near the house. (The power lines were close enough that, when outside, you could hear the 60 Hz hum.)

Tony