Topic: Lightning Streamer, reflection or digital internal reflections?

[David C]

Doesn't lightning change colour with the amount of moisture in the air?  I've seen many, may bolts in pink and purple due to being rain wrapped or near the curtain.  Nice bright white strokes seem to be outside the area of precip.  I've also seen purple/blue and pink bolts in intra-cloud stuff - could be a lot of things - illumination from other IC stuff, moonlight and of course the rain! 

Anyway that's another topic .....

Mike

Mike,

Yes it does, but I'm talking about a continuous 'switch like' effect observed with very clear inter (not intra...sorry!) cloud bolts and well away from the precip cores). It was as if someone had two filters and was switching them around for a good few hours!  I doubt there would be much variation in moisture in thos situation (given the spatial and temporal constraints -- slow moving supercell storm and change in colour every few minutes).

[Shaun Galman]

Hi David,
I was going to reference that film image taken by Johnny Autery in 1984. (I hope I catch a shot like that one day!) He says that the artifact coming from the TV antenna was a small bolt, but I would tend more towards it being a streamer, it looks like one coming from the tree top next to the mian strike though it looks more likely to be a cg branch? The roof of the building next to the tree (behind the fence post) looks interesting with a possible small streamer on the facing edge, but not seeing another clear day image I can't be real sure I can only offer that as my opinion? I was sent a recent copy of National Geographic by a friend in Florida with a great feature on lightning. (you may have seen it) It had Johnny's image in it as a full page thats nice and clear, along with a small story from him. They have also included a partial description of streamers, calling them Upward positive leaders, but didn't really go into any detail?

One of the best night time examples of a streamer I saw was video footage from the Brisbane Storm Chasers Site. It was located on the right side of the screen beside a pool in a yard while the main strike was more left/center, if my memory serves me well. It was very bright.

Next time we have a good active cell come by (I think the season may be drawing to a close at the moment) I will set my camera up with half ground and half sky so we can get a nice look at these things eminating from the ground or objects (I may even place a few around in the interests of "backyard" science) with some detail, fingers crossed!

The colouring of lightning has always fascinated me. I remember seeing a documentry a while back on lightning that explained if the cg's were more blueish/white hue, it was more Nitrogen content and a pinkish/red hue was a result of more Hydrogen in the atmosphere? I'll take a neutral stance on that for the moment, interesting thought though.

Cheers guys. Maybe we should've started a "Streamer and related articles" forum lol?
Shauno

[David C]

I'd really like to see the higher res image so I might fish out that NG article Shaun! It is a bit hard to make much else out on the jpeg I can only make out the two obvious streamers. Lightning is so interesting and complex that getting a separate forum might not be a bad idea.

One thing I have noticed it that there is some difference between lightning 'traits' in different areas. Read this extract from Wikipedia: lightning (and pay attention to Oklahoma Jimmy!!!!!!!!!)

"However, it has been observed from experiments that different locations in the US have different potentials (voltages) and currents, in an average lightning strike for that area. For example, Florida, with the largest number of recorded strikes in a given period, has a very sandy ground saturated with salt water, and is surrounded by water. California, on the other hand, has fewer lightning strikes (being dryer). Arizona, which has very dry, sandy soil and a very dry air, has cloud bases as high as 6,000-7,000 feet above ground level, and gets very long, thin, purplish discharges, which crackle; while Oklahoma, with cloud bases about 1,500-2,000 feet above ground level and fairly soft, clay-rich soil, has big, blue-white explosive lightning strikes, that are very hot (high current) and cause sudden, explosive noise when the discharge comes. Potentially, the difference in each case may consist of differences in voltage levels between clouds and ground."

Ok wikipedia might not be entirely reliable but it is getting to be very good and I can tell you, Great Plains Cgs can be like atomic bombs going off!!! I assumed it was the landscape (resulting in a healthy shockwave). What about Gene Rhoden's observation that tornadic supercells often produce smooth channel lightning - it held true on May 12, 2004 I know that - such as this:

 

I jibbering now, but there is so much to learn with lightning. Yep another forum!!

[Jeff Brislane]

Thanks For the Reply Dave C, I've been waiting for ages for someone to actually reply on the orgional subject and at that, taking into account that it was NOT shot with video. Can I say that again? It was not shot with video. So forget the problems associated with video artifacts with this photo please as they have no bearing on SLR cameras. As for luminosity and whether or not a filimant can actually be seen near a major strike, I think the photo Dave C has posted shows that it very well can and quite clearly too. Remember it is about 100m or more away in that classic photo but in mine were talking 5m! Yes only 5m away so there's no doubt a streamer would be visable.

Dave C, the branch in the image went directly overhead and was within 100m of the ground and it came off the actual main cg channel which struck about 50m or less to my rear left out of the image. I heard gunshot style instantaneous thunder from it, so the conditions were ideal for a streamer in my immediate vicinity.

Please everyone note the fact that the rain drops immediately in front of my car have actually been illuminated by the lightning. That suggests exactly how close it is. Please if anyone else has a photo with evidence of such close lightning by all means submit it so I can see another example.

Now I also provided another example of a close cg photographed through a window with no reflections by Nick Moir. Any comments on that? Actually I have another photo of a cg that struck 100m away a few years ago i'll find and post.

[Jeff Brislane]

Here is another close Cg from 2002. It's a good example of a non-branching cg and it struck in the backyard of a house about 100 to 150m away. It was a single strike with no pulsing and no branches at all and even though it's so close it's not overly bright. This example is a good contrast to get an idea of how close is really close to a lightning strike, as you can be 100 to 150m or so meters away and it's very close at the time and you get nearly instant thunder but it's not that close that it lights up the rain around you.

I know it's not the best scan of this photo which was shot with film but in it you can see a reflection of the lightning on the roof of the house that it nearly struck.