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JessM
2005-Sep-13, 01:17 AM
I was wondering, is it possible to see a rainbow in the flash from lightning? There was a big thunderstorm the other night, and I *thought* I might have seen a rainbow out of the corner of my eye... of course the light comes and goes so fast there's no chance for a better look. So, is this possible? How exactly lined up would things have to be to see it? Has a lightning-rainbow ever been photographed? (I'd imagine the amount of chance involved in photographing one would be phenomenal!)

Just wondering.... ^_^;

antoniseb
2005-Sep-13, 01:38 AM
I'm guessing that the fact that lightning gives off light from a distributed area will affect the visibility of a "rainbow", or at least of a refraction pattern of some kind. You'd need to be lucky enough to be facing the other way of course.

Another aspect of this that I'm wondering about is this: What is the spectrum from lightning? is it an emission line spectrum from ionized Nitrogen and Oxygen? How would that affect the rainbow if you could somehow get a small point-source lightning flash?

jkmccrann
2005-Oct-21, 04:51 PM
Were you looking through glass at the time?

Ken G
2005-Oct-21, 07:15 PM
I'm not sure about the spectral-line-emission issue, that does seem interesting, but I agree that angular spread would have to be a problem in making a rainbow with lightning. The bright lightning I've seen was clearly emitted along a long line. Is there a more likely optical illusion kind of explanation?

Enzp
2005-Oct-22, 07:00 AM
Do you wear glasses? If you do, and this was a corner of the eye thing, it could have been a prismatic effect from the edge of the lens. My current glasses have matte finish on the edges of the lenses, but once I had a pair with the sides of the lenses polished, so they let images in through the edge if you looked there. I got all manner of artifacts from that in my peripheral vision. I hated it and refused to have them made that way again.

But I do believe a lightning rainbow is possible.

pghnative
2005-Oct-24, 01:03 PM
My guess is that a rainbow from lightning is not possible because the lightning isn't far enough away to result in parallel light rays. Keep in mind that when you see a rainbow, the red is coming from different water droplets than the yellow, green, etc. It only forms a nice separated bow because each water droplet received light from the same angle (relative to the observer).

ToSeek
2005-Oct-24, 03:10 PM
A primary rainbow would be observed 138 degrees away from the light source. So if you were looking toward the lightning, it's unlikely you would have seen a rainbow produced by that lightning (assuming there even is such a thing).

Eric Vaxxine
2005-Oct-24, 03:17 PM
If there is a rainbow from lightining would the phenomenom of the light outside the rainbow always being darker than the inside, also be relevant?
(or is it the otherway around?)

Ken G
2005-Oct-26, 07:45 PM
My guess is that a rainbow from lightning is not possible because the lightning isn't far enough away to result in parallel light rays. Keep in mind that when you see a rainbow, the red is coming from different water droplets than the yellow, green, etc. It only forms a nice separated bow because each water droplet received light from the same angle (relative to the observer).
That, coupled with the length of a lightning streak, is a confirmed kill on this possibility.

Ricimer
2005-Oct-30, 05:49 AM
however, it doesn't kill the possibility that the lightning created a flash of color. It may not have been a nice pretty curve, but it could still create a flash of color.

Ken G
2005-Oct-30, 05:58 AM
You mean the spectrum of the heated air itself could have a color? I suppose, like the way meteors do sometimes, but that certainly isn't the usual way, we've all seen lightning and it's pretty white. As for internal reflection in water droplets, the different colors will be overlapped to the point of washing out any color, due to the combined effect of the source being both extended and not that much farther away than the water drops doing the reflecting. I think we're looking for an illusion here.

Ricimer
2005-Oct-30, 07:03 AM
What exactly do you mean by an illusion? Something that would make it appear as if there is a streak of color, but there isn't one?

I still don't see anything to rule out a chance streak of color. It's a storm, water is all over the place, and it may not be uniform.

We have a source of light, and a refracting medium. every now and again its possible conditions are right for a flash of color (i.e. they don't all wash out to white again).

Ken G
2005-Oct-30, 07:58 AM
We have a source of light, and a refracting medium. every now and again its possible conditions are right for a flash of color (i.e. they don't all wash out to white again).
Well, we are looking for more than a flash of color in the OP, we are looking for bands of color that are reminiscent of a rainbow. That's what is impossible when you have a linearly extended light source that subtends an incident angular spread that is wider than a rainbow. Under those circumstances, which appear appropriate to this situation, each individual water droplet will yield a spray of colors that must wash out, except for the outermost color in the spray (violet?). Even that is washed out if the water droplets have a depth that is nonneglible compared to the distance of the light source, as I would expect in most cases. So I would agree with Ricimer's assertion that many things are possible, but we can also eliminate most possibilities in real situations. Kind of like UFO explanations, I should imagine. The reality here is, the OP fell victim to either a trick of the eye, or a trick of the imagination.

Ricimer
2005-Oct-30, 02:05 PM
first, out of the corner of his eye, a flash of color could easily be misinterpreted as a full rainbow, so lets not get stuck on that requirement to much.

Second, if the rain was say, only to one side of the lightning strike, and the strike was fairly linear, that could cause a streak of color very much like that observed from a standard discharge tube (where you have an extended source as well).

Third, I'm not saying the cliche, "anything is possible". Merely that we have a light source, and a refracting medium. That it's possible to get a streak of color, even a rainbow (or a multicolored emission spectrum from the very ionized and mixed composition of gas that, under these conditions could easily be mistaken for a full continous spectrum, a.k.a. rainbow). The conditions are just relatively particular, but not out of the range of possibility. So it would be "rare" but not impossible.

Ken G
2005-Oct-30, 02:23 PM
first, out of the corner of his eye, a flash of color could easily be misinterpreted as a full rainbow, so lets not get stuck on that requirement to much
Fair enough, we'll restrict to any color at all.


Second, if the rain was say, only to one side of the lightning strike, and the strike was fairly linear, that could cause a streak of color very much like that observed from a standard discharge tube (where you have an extended source as well).

Exactly, but this relates to the requirement that the droplets be in a sheet or a plane, like a diffraction grating is.


The conditions are just relatively particular, but not out of the range of possibility. So it would be "rare" but not impossible.
Agreed. Indeed, there is value in considering the requirements to get such effects, one learns a lot about why we see rainbows but not other color effects. Still, if we want to theorize about the most likely explanation to the OP, I find the required conditions for a normal internal-reflection generated color flash to be unlikely in practice. But to pursue it, more investigation would be required. We can just agree to leave the matter unsettled instead.

JessM
2005-Nov-03, 01:08 PM
Should have posted back on this earlier... ^_^;

To answer questions: I was looking through a window at the time, but I don't wear glasses.

It's a very interesting discussion. ^_^

publiusr
2005-Nov-03, 06:56 PM
Lightning can even leave shadows. I seem to remember a lightning bolt's shadow left on a volcanic plume behind it in one photograph.

19brigid
2009-Aug-10, 07:12 PM
I have been seeing a lot of these in the last month. I was staying in Ruidoso Downs, NM.
In NM it is the monsoon season. Everyday was sunny and once a day for about 30 minutes a huge thunder/lightening storm would pass by. When the storm got to us, it had just been sunny. Some of the lightening bolts seem to strike right where we were. It either rained or hailed.
I first saw them outside, and they were always a quick flash of multicolored light, usually going diagonally or horizontally - never vertically. It was as if they flew by in a horizontal flash.
Then I was in my van and one shot past me inside the van, doing no harm. I decided then, they must not be lightenng, but rather some fragment of a rainbow.

I have seen perhaps 20 of them. I wear glasses but they are frosted on the edges.

I do not know what they are, however I wanted to contribute that I too have seen many of them.

busygirl
2017-Jun-20, 03:30 AM
So, I know it's years later since you posted this, but I was looking up the phenomenon after just experiencing it. I saw it occur 3 times this evening. Also my boyfriend also saw it the third time. We were looking out the car window and the lightning was very close and they were short bolts like probably cloud hopping low to the ground. There was no rain, just a lot of sheet lightning and other larger lightning bolts far off. There is also a large area about 2 hours drive from here that is completely without power, so I'm also wondering if it might be something closer to aurora borealis/solar flares but it was definitely overcast and now and hour later it's raining lightly. Anyway, not sure if the affect is created by the car window or the closeness to the bolt, but you were definitely not imagining things.

BigDon
2017-Jun-23, 03:22 PM
Do you wear glasses? If you do, and this was a corner of the eye thing, it could have been a prismatic effect from the edge of the lens. My current glasses have matte finish on the edges of the lenses, but once I had a pair with the sides of the lenses polished, so they let images in through the edge if you looked there. I got all manner of artifacts from that in my peripheral vision. I hated it and refused to have them made that way again.But I do believe a lightning rainbow is possible.

So THAT'S what's doing this to me.

Welcome to the boards and thanks for bring this up Busygirl!