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
 
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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.
 
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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!
 
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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.
 
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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
 
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.
 
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.
 
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, 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!
 
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.

bigone.jpg


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.
 
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.
 
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. :confused:




chassorages1.jpg
 
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.
 
Don't think its camera movement....the photographer cannot possibly move the camera that fast!

This type of photograph has been taken before, although this is certainly the best I've seen. In Uman's book "The Lightning Discharge" (1987), there are two pictures of these strange upward leaders next to the return stroke (pp 103, 105). These pictures are a dead ringer as to what is here. Uman labels them as 'unconnected upward leaders'...and are very rare to capture.

If I had to guess (no expert here), as the stepped leader process is coming down towards the ground, it could be that there are several 'points of interest' that gets energized on the ground, and form 'upward leaders', and only one is selected, thus the return stroke goes when the stepped leader comes near the surface.

Awesome picture...I get as excited about lightning as I do tornadoes!

Tim
 
WOW! that has got to be one of, if not the, greatest lightning photos of all time.

Pat
 
hello Christophe (how are you since friday in Geneva?), you speak very well english and spanish!!! not me! (sniff)

Just my opinion for this wonderfull strike of Sandro FEDRIGO (Geneva)
To my point of view isn't a movement! it's really 3 ascendant tracers... Why?:
if it's an only ascendant traceur with 3 impression by moving, so the descending tracer must be 3 impressions also!!!! but Now isn't the case ;)

Just a spécial greeting and congratulation to Tim Samaras and Mike Hollingshead (my favorite US stormchasers with Jeff Piotrowski ;) )

See you soon
Fryz
 
interesting photo. The first one Ive seen yet. Almost an errie view. Wonder what it would have looked like without the camera moving during the exposure. Very interesting....

-gerrit
 
Conclusion: 3 separate streamers are real

I generally agree with Jeff, Dan and Mike.

1. If camera shake caused this, if there would be just 1 upward catching streamer it would appeared smeared like in those Boys camera photos. We don't see this. Why would such a streamer pulse?

3. The 4 do indeed not take the same path as each other.

4. The camera shake must be very fast at the exact moment of the strike (starting actually just before). This would seem impossible to do, so it appears that the movement was either before or after the flash, or both, but not all during the exact moment of the flash. The motion of the many lights in the distance was wiggly and also in vertical direction which would have displaced the leader over maximally the same angular distance. This may match horizontally indeed, but not vertically! Rather, the return stroke highlights the water surface, which is at equal level with the leaders. If the camera motion had any effect on the lightning this would have been impossible. So, the motion of the camera was too slow to cause an effect on the lightning itself.

5. Also the *downward* leader would have to be similarly displaced like in a Boys camera streak photograph. One cannot see it (the diffuse effect is coming from internal reflections in the lens). So again, the motion of the camera was too slow to cause an effect on the lightning itself.

Conclusion: The camera shake had too slow speed to separate the lightning processes: the 3 streamers are real and unique from each other.
It would have been perfect if the camera remained steady so that nobody would need a whole discussion to believe it.....

Oscar
 
My Opinion: Three Separate Streamers

I generally agree with Jeff, Dan and Mike.

1. If camera shake caused this, if there would be just 1 upward catching streamer it would appeared smeared like in those Boys camera photos. We don't see this. Why would such a streamer pulse?

3. The 4 do indeed not take the same path as each other.

4. The camera shake must be very fast at the exact moment of the strike (starting actually just before). This would seem impossible to do, so it appears that the movement was either before or after the flash, or both, but not all during the exact moment of the flash. The motion of the many lights in the distance was wiggly and also in vertical direction which would have displaced the leader over maximally the same angular distance. This may match horizontally indeed, but not vertically! Rather, the return stroke highlights the water surface, which is at equal level with the leaders. If the camera motion had any effect on the lightning this would have been impossible. So, the motion of the camera was too slow to cause an effect on the lightning itself.

5. Also the *downward* leader would have to be similarly displaced like in a Boys camera streak photograph. One cannot see it (the diffuse effect is coming from internal reflections in the lens). So again, the motion of the camera was too slow to cause an effect on the lightning itself.

Conclusion: The camera shake had too slow speed to separate the lightning processes: the 3 streamers are real and unique from each other.
It would have been perfect if the camera remained steady so that nobody would need a whole discussion to believe it.....

Oscar

Sorry for coming into the discussion so tardily!

I believe that this excellent photo shows three separate streamers (upward moving unconnected leaders, to quote the Uman/Rakov book).

In addition to the points cited by Oscar van der Velde, I should like to point out that the buoy is clear evidence of three streamers. If the image was of a single electrical discharge which was separated in time by camera motion, then the buoy would appear four times: once for each pulse represented in the frame. Each pulse is bright enough to illuminate the buoy, so the only conclusion I can draw from the single buoy is that the image depicts four discharges around a single buoy.

I'd also like to comment that this is only the third image I have seen which depicts any branching on a streamer, and it is certainly the clearest of the three (the others being lightning on a NJ beach and Autery's excellent tree image).

Finally, this is the only image I have seen in which more than two streamers are visible in close proximity to the main lightning flash.

Dan also mentioned the small projection which appears attached to the buoy. While I have nothing to support my opinion, I suspect that this is some non-electrical artifact. This hunch is based mostly on its magnitude of illumination, and the "L" shape just above the buoy. It just looks different than the others in a way that makes me think it is not related.

I hope this helps the discussion!

Ken
 
...If the image was of a single electrical discharge which was separated in time by camera motion, then the buoy would appear four times: once for each pulse represented in the frame. Each pulse is bright enough to illuminate the buoy, so the only conclusion I can draw from the single buoy is that the image depicts four discharges around a single buoy.Ken

Exactly what I was thinking. The camera shake depicted by the lights along the shore looks to me to be either a bump at the end of the exposure with the lens traveling down and toward the right, or more likely, the camera quickly settling into its still position immediately after the shutter release (lens shifting up and to the left). This is difficult to avoid without the use of some type of remote release. Even on a tripod, pressure from a finger on the release can position the camera out of its angle of rest.

It also appears that the closest non-discharged leader has attracted a branch from the main channel of the discharge. In two dimensions it's impossible to be sure. It would appear, though, that the "choice" was very "difficult". That's the only way I could think of to put it. :)

Marvelous and extremely fortunate catch!
 
Well, I have a similar photo to post that actually depicts lightning streamers or a returns strokes. Have a good look at the streamers rising upwards from the tree tops in close proximity to the actual bolt. I think it is very similar situation to the lighting leaders over Léman Lake posted some time ago. Just a note, it was taken this July in Czech republic.
Oops, the uploaded picture is too small to see details, so follow this link:
http://ukazy.astro.cz/gal/20070720MarekPecka-lightning-strike_blesk2a.jpg
 

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Wow, Tomas!

Another marvelous catch! I don't think there's any question there.
 
Awesome shot, Tomas! Looks like FIVE definate leaders there - wow. It looks like you can see a little bit of the lightning channel traveling down a tree near the ground, showing through the trees.

There are only a handful of stills in existence showing CG-associated upward leaders, so this (and the original photo posted in this thread) are very remarkable.
 
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