Lightning leaders over Léman Lake (CH)

[Christophe Suarez]

Good evening,

The 10th of september, during the evening, there's been a nice thunderstorm over Geneva. Several storm chasers were shooting in the area. One of them , Sandro Fedrigo, took by chance a rare photo. I would suspect the camera shifted a bit during the exposure and made possible the following photo: http://membres.lycos.fr/joose/chassorages1.jpg

The complete story is visible here: http://foudre.chasseurs-orages.com/viewtopic.php?t=704 . It's French speaking but the photos are self-explanatory I think.

I would appreciate your comments on this phenomenon.

Chris

 

[Dan Robinson]

Very cool. I don't think I've ever seen such extensive upward branching documented on upward-moving leaders associated with cloud-to-ground flashes.

I'm curious though if there are three separate leaders, or just one leader separated in time on the exposure due to the movement of the camera. The reason I suspect this is that the stepped leader becomes brightly luminous in each of its discrete steps as it propagates, separated by weakly luminous or non-luminous intervals. The associated upward leader should mirror the luminosity of the descending stepped leader, which might explain the gaps in the exposure should this turn out to be only one leader.

 

[Jeff Snyder]

Interesting photo, but the upward-directed leaders are a little puzzling. On one hand, it may have been one single leader, with slight 'shaking' of the camera yielding what appeared to be 3 discrete leaders. However, given that the timescale involved is likely on the order of one or two milliseconds, I wonder if we'd see discrete leaders if this really was the case. In other words, why wouldn't the streamer just appear to be "smeared" as it extended upward to meet the stepped-leader coming down from the cloud? I'm not sure why the camera would see discrete leaders in the miniscule amount of time involved here (I think the time-scale of most streamers is on the order of 1ms). In addition, it would seem odd the the camera would 'shake' noticeably before the streamer met the leader, but not shake after they meet (and the return stroke occurs). I suppose that most return strokes occur on the order of several microseconds -- much faster than streamers (subsequent return strokes from dart leaders along the same ionized path can lead to the 'flickering' that we sometimes see with lightning). On the other hand, if these were seperate, distinct streamers, I'd be surprised that they occurred in such close proximity to each other.


What are the orange 'lights'-looking things on the right of the photo (right above the water)? That appearance looks like a familiar 'blur' caused by camera shake. However, the distance separating those appears to be less than the distance seperating the streamers, which seems odd if the camera was 'shaking' at some interval (in which case, wouldn't the distance seperating the streamer illuminations and the distance seperating the orange-thing illuminations be the same?). In addition, if they are lights, they appear to blur to the lower-right, before a discrete jump occurs back to the right. Of course, they may have been a bank of lights that 'blurred' to the 'down and right' direction, but then we'd expect to see the same blur pattern with the streamers. If the orange lighting is 'stringy' like that, and the discrete right-ward jumps are caused by camera shake, then that'd make a little more sense to me. The distance between the discrete 'jumps' with the orange things still appears to be less than the discrete jumps with the streamer(s), however.

Interesting photo regardless of what happened!

 

[Chris Vagasky]

And is that a person between the second and third streamers?

 

[Mike Hollingshead]

Everything about the bolts look legit to me. I'd assume any of that movement came at the end or the beginning of their shot since for the most part the objects are in focus. The leader/bolt spacing makes me think of Hank's awesome image from this year of the very close lightning strike. But anyway, the movement appears to have happened before or after the bolt.

Out of curiousity, what is the time-scale of a stacato bolt? I'm guessing pretty short and those can blow out a wide open aperture with ease.

 

[Christophe Suarez]

But anyway, the movement appears to have happened before or after the bolt.

Joose says the camera moved because of the strong explosion after the strike. I always thought there's been a shake just before, the base of the lightning shows the movement, symetrically with the light shifting on the right.

To me, the question was: are the leaders on the left a different portion of the same channel at different times, or do we have here several leaders ?
Jeff, can't we imagine that the small leaders are coming in pulses, very short ones, that would be short enough to be sharp on a slightly shaked exposure ?

Also Joose asked about this strange orange form on the right. Nobody could really answer on the French forum.

Chris

 

[Dan Robinson]

Upon closer inspection it does appear that these are three separate leaders, as their channel paths do not match one another.

There appears to be a fourth leader rising from the object (a bouy?) floating on the water between the second and third leader.

The ghostly orange form to the right of the main lightning channel looks like the exposure of raindrops on the lens from the ambient city lights prior to the lightning.

 

[Mike Hollingshead]

Joose says the camera moved because of the strong explosion after the strike. I always thought there's been a shake just before, the base of the lightning shows the movement, symetrically with the light shifting on the right.

To me, the question was: are the leaders on the left a different portion of the same channel at different times, or do we have here several leaders ?
Jeff, can't we imagine that the small leaders are coming in pulses, very short ones, that would be short enough to be sharp on a slightly shaked exposure ?

Also Joose asked about this strange orange form on the right. Nobody could really answer on the French forum.

Chris

I don't think there was any real movement during the strike.

What is this about the base of the lightning showing the movement symetrically with the light shifting on the right? I guess I don't see that.

The smears of light almost look like what you might expect if someone was to grab ahold of the camera and then quickly move it before the shutter was closed. Notice the clustered area is a bit brighter in a moved area before it quickly trails off. Someone could do that with a night shot and have it look just like that, with the building in the background in focus as well as the lightning strike. The only thing that would blur would be what was still illuminated when the camera moved. No matter what happened there I'd assume camera shake has no effect on this, especially considering the sharpness of the bolts.

I'd be willing to bet that orange line of lights came from some portion of the shoreline, not right behind where it looks, but perhaps well off to the side. I bet that long area and the other one to the left line up down the shoreline some. If you abrubtly bumped the camera after the strike it could jump to a much different location and get that look from lights on the shore somewhere.

 

[Christophe Suarez]

By the way, Mike, here is the initial comment of Sandro Fedrigo:
> le (gros) bougé est dû à l'onde de choc donc après l'éclair.
The (big) shake is due to the shock wave after the strike

That would explain the photo. But... the last part of the lightning channel seems to show a movement from left to right, do you see the channel becoming larger 5m or so above the water ? This is where and when I suspect a small shake. Of course this is just an idea that might be totally wrong. The photo is already travelling around the world, I'll try to compile the information and let you know.

Chris

 

[Jeff Snyder]

Jeff, can't we imagine that the small leaders are coming in pulses, very short ones, that would be short enough to be sharp on a slightly shaked exposure ?
Chris

That'd work, but I didn't think streamers "pulsed" like that. I'm no expert on lightning, but I haven't heard of pulsed streamers. So, that would lead me to believe that they are 3 discrete, seperate streamers in very close proximity. I think movement would have lead to a 'smeared' appearance unless the camera smoved-stopped-moved-stopped-moved-stopped in the course of a millisecond or two. It's certainly not common to catch streamers, so that's quite a shot!

 

[Mike Hollingshead]

By the way, Mike, here is the initial comment of Sandro Fedrigo:
> le (gros) bougé est dû à l'onde de choc donc après l'éclair.
The (big) shake is due to the shock wave after the strike

Chris

That seems like quite the shake to have been caused by a lightning bolt at that distance. I suppose it is possible, but it just seems a bit much.

I mean sure I'd expect a person to feel it(I've been about that close at least once, but never caught it on a still!) but I guess I don't recall anything able to move a camera around like that.

 

[Dan Robinson]

The shock wave (supersonic wavefront) from a lightning strike only propagates a maximum of about 25-30 feet at the high end. After that, its a sound wave that wouldn't be capable of exerting force enough to move a camera. Loud low-frequency thunder can rattle objects, but probably not to the degree as is seen in the photo.

I know from experience that it is hard to not be at least a little startled when a close strike hits like that, which can easily account for the camera movement when the photographer jumps in reaction.

 

[Susan Strom]

Stunning, awesome!

 

[Christophe Suarez]

Hi Susan, nice to hear from you through the forum...

I've also seen a clever explanation of the photo made by a scientist on a spanish forum. Of course it's in spanish. If some of you can understand the Cervantes language, here's the link... http://www.cazatormentas.net/foro/index.php?topic=8694.msg149391#msg149391

>Ese movimiento, adecuado o inadecuado, parece haber captado la guía >de conexión o descarga que aparece como respuesta por simpatia e >inducida a la guía escalonada
This movement, adequate or inadequate, seems to have picked-up the leader or discharge, appearing after and induced by the streamer... (I hope my translation is correct).

It would confirm the fact that the phenomenon is visible thanks to the movement of the camera. But... do we see here several streamers or the same one being displaced during the exposure ? Hmmm... the streamer is supposed to be a very short phenomenon (micro-seconds).

But it seems that the distance between each streamer is the same, that's a bit strange isn't it ?

Maybe it is just more simple than that: we just see here several streamers. But the fact that the camera moved a bit during the exposure is however evident (lights). Of course it did not affect the rest of the photo except the lights, as it possibly happened at the end of the exposure, maybe after the previous lightning which was already close enough to give a scare to the photograph.

One last thing, there's a bit of perspective here, and the main discharge seems closer than the first very small streamer, they look to be displacing like the lights.

Since the beginning my opinion is that we can see here 4 different phases of the same lightning.

 

[Dan Robinson]

It doesn't look like they are the same leader as the main return stroke channel. For that to be the case they would all three (four) need to be the same shape at the bottom, where they would have a common path on the exposure. In the photo it looks like they are all shaped differently at the bottom.