Photograph by Carlos Gutierrez, UPI Photo/Landov
Olive Heffernan in San Francisco for National Geographic
Published December 10, 2013
In May 2008, Chile's Chaiten volcano violently erupted, spewing out clouds of dirty ash and illuminating the dark sky with a most unusual kind of lightning.
Photographer Carlos Gutierrez captured the dramatic nighttime display—in which green lightning emerged from the ash cloud—in the striking image above. (See also "PHOTOS: Chile Volcano Erupts With Ash and Lightning.")
The origin of the bright green lightning bolts remained a mystery until atmospheric scientist Arthur Few, of Rice University in Houston, became curious about the phenomenon. "I thought, 'That's funny; why don't we see this in lightning storms?'" said Few at the meeting of the American Geophysical Union (AGU) in San Francisco on Monday.
Although green lightning seems unusual, Few now suspects it occurs during all thunderstorms but is concealed inside clouds.
The concealment results from the structure of storm clouds. On the inside, the clouds contain ice crystals that are either positively or negatively charged. Surges of electricity occur between positively and negatively charged regions within the cloud—lightning—but they remain inside, unseen by even the most committed storm chasers.
In contrast, volcanic ash clouds carry their electrical charges on the outside, where they are sparked by fragments of rock forcefully ejected into the air during an eruption.
Few thinks that the bright green bolts seen at the Chaiten volcano are simply "positive streamers," or a current-transferring electrical surge from a positively to a negatively charged region on the outside of the cloud.
If only we could see inside thunderclouds, he suggests, we would see green lightning more often.
Green Color Explained
But why green? The green hue is given off by electrically excited oxygen atoms, says Few. He thinks the same process paints the sky green during the vivid light shows of the aurora borealis that can dominate northern skies in winter.
This phenomenon may have also colored the tail of Comet Lovejoy as it passed overhead in November.
For the time being, however, Chaiten in Chile is the only volcano where green lightning has been photographed.
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The first time I've seen this in photo and it is very amazing site that everyone should take care not to get closer.
As a meteorologist and photographer who took atmospheric physics and optics as part of my degree, I couldn't help but chuckling after reading this! Let's please practice safe science.
" He thinks the same process paints the sky green during the vivid light shows of the aurora borealis that can dominate northern skies in winter."
This is the only FACTUAL part of this article. The common green and red hues of the Aurora *ARE* due to electron excitation of oxygen atoms at the upper levels of the atmosphere (about 150 miles up). Rarer blues and purple are from Nitrogen.
As for lightning.
First, the well-published photograph above has been well documented. Clearly, Mr. Few didn't do his homework. The green "bolt" coming from the pyrocumulus doesn't really even exist. It's a camera lens issue due to a lens reflection. An inverse mirror image matches with the actual white cloud-to-ground stroke on the left!
Secondly, lightning and Aurora are two completely different things. All lightning is white. Period. There is no discussion to be had. Unlike the Aurora, the visible light you see in lightning is NOT due to electron excitement of atoms by the solar wind, but rather pure heat. The temperature of that bolt averages about 50,000 degrees Fahrenheit, producing brilliant white light. That's why you hear thunder! It's the rapid expansion and contraction of air molecules in the lightning channel caused by the immense heat produced.
Thirdly, so why do we see yellow and reddish hues with lightning in the distance? This is simply optical scattering at work. The farther away the storm is, the more air molecules, rain and/or haze/dust exists between you and the lightning bolt. The composition of our atmosphere (mostly nitrogen, oxygen and argon) causes shorter wavelengths of light to be scattered at a 3-4 times the rate of longer wavelengths. The more air between you and the object, the more that shorter wavelengths of light are scattered -- leaving us with long (yellow to red) wavelengths to see. The same yellow or reddish lightning bolt in the far distance would appear bright white if you were up close. This the same reason why the moon appears yellow or sometimes even reddish on the horizon, but becomes bright white as it rises. At horizon level that white light is being scattered by your view through dense air molecules, dust, haze, etc... As the moon rises, you're looking up through fewer and fewer scatterers.
Using these principles and thinking about the composition of our atmosphere, you can now deduce why the sky is blue. It's NOT due to reflection of sunlight off the earth's oceans. It's scattering.
Check with Wiki "Scattering"
: Rayleigh scattering (small particle compared to wavelength of light)
: Mie scattering (particle about the same size as wavelength of light)
: Geometric scattering (particle much larger than wavelength of light)
Learn to understand reflection, refraction, diffraction & interference, aberration uam simply the optics.
Colors of clouds and the sky are based on Rayleigh-Scattering.
Rainbows, spectral colors are based on reflections and refractions.
Tyndall-Effect, Zodiac Light, White Rainbow uam are based on Mie-Scattering.
Daylight in your room is based on geometrical scattering.
Light-flares are light phenomena within a lens-system. (reflections, refractions and others)
Please, informe yourself with Prof. Walter Leewin at MIT "For The Love Of Physics" via You Tube.
I wish you a lot of pleasure. Crigs
I don't agree with this simplest of explanation because 20% of our atmosphere exists out of oxygen, so all lighting would be green if this was true. A better hypothesis for green lighting in volcanoes (as some already mentioned) are probably certain elements in the dust clouds (like copper, mercury) that emits green light when the electrons from such elements fall from an excited (High energy) positions back to normal (lowest energy). Also metals in the dust cloud will conduct electricity much better and in this process become that hot that the electrons in these atoms come in an excited state (high energy state) thus emitting the light according to the Pauli exclusion principle. There are also many gasses in our atmosphere that have their typical colors (spectrum) when in an excited state like neon and argon. normal lighting light seems to be white but we should not forget that white light is an combination of all colors in the spectrum. You can see this when sunlight (white) is diffracted by fine water droplets in the air (during or after rain) when making a rainbow. Volcanic dust has so many different elements and probably the metals (copper, mercury, Iron) will a be part in this process of colored lightning.
Common guys, wake up, this is just a lens relfection. And this was already obvious when the picture was posted back then.
I traced a line over the green lightning, copied it on top of the regular one, flipped it horizontally and vertically and... what do you know, perfect match. I guess I solved the mystery of the green lightning too!
I saw several cloud-to-ground bolts of brilliant green lightning during Hurricane Andrew. I was near downtown Miami, looking west. I can say with absolute certainty that the phenomena of green lightning is not limited to a vicinity of volcanic activity.
I think the explanation on such green flash given in this article is more or less dissapointing. If the oxygen is the answer, the lightnings occurring outside of the ash cloud should be green, or at least, such green flashes should be not rare.
I think Mie theory on scattering can say a better answer.
The reason why we see red sky when sunsetting is because of Reyleigh scattering of the atmospheric molecules. During the sunset, extremely small particles like molecules let all of the blue light component and most of the green component scattered out from the incident almost white sunlight so that we see the red light: this is Reyleigh scattering.
However, if particles are larger than 1/10 of the incident light's wavelength (i.e. larger than several tens of nanometer), Mie scattering should be considered. Mie scattering caused by large particles (like mist, clouds, ashes, smokes and something like that) makes little influence on the incident wavelength so that we see white clouds at daytime (not blue- or yellow-colored clouds)
Mie scattering caused by "small particles" is very interesting since this is located in somewhere between Reyleigh scattering (Red-shifted resultant light) and Large-particle Mie scattering (resultant light with untouched wavelength). This mechanism can make any color between red and blue. The color we see is determined by the shape and the size of the ash particles in the clouds.
This is why I think Small-particle Mie scattering is the answer.
Last night , while coming back from the Grand Canyon, a meteor came streaking down at about a 45 degree angle in the eastern sky traveling north to south, in bright green. It was slow enough to watch for 3-4 seconds. It was as green as the green in traffic lights.
As a child I lived on the border between California and Arizona(1966 or so). During one of the rare desert storms over the Quartsite hills.we saw green lightning.
although we saw little of the bolts the reflection of the lightning in the clouds was incredible.
Used a camcorder camera pic,. lightning is very fast, hard to take picture, as soon as it flashes, you click & disappear instantly
Mike Hall is absolutely right - this is just sensor / lens reflection. Just copy the portion with the green lightning, rotate 180 degree and paste it onto the real one (with transparency turned on). It matches 100 percent, it is indeed the same lightning bolt. Funny (or embarrassing?) that it takes an actual scientist to come up with a theory about it. And then get NG to publish it!
It's cleared but only for the volcanoes, how about the normal cloud 'cause on a stormy night i've seen many green lightnings though there isn't any voalcanoes here (Antananarivo - Madagascar)
Okay. So some say it's a mirror image caused by a filter on the lens. Very possible. No-one has said that the color of the bolt at a volcano could be caused by the minerals in the air that the current followed. Could this have been copper in the ash that the lightning ignited?
As a professional outdoor photographer and storm chaser lightning is my favorite subject. In this case I honestly do not see the mirror effect that Mike Hall notes. I do see a similarity but no mirror.
I have never seen in the thousands of images I have taken a green bolt. I have gotten white and brighter white depending on how close they were to me.
I've not had the opportunity to photograph a volcano but life is not over yet. Perhaps if I do I'll see one or more green bolt then.
It would be interesting to have the scientists speculate here on the mineral in the cloud aspect I propose.
The article turned up serendipitously in time to explain what a friend and myself observed from our hostel window in Pune, India, just a week ago. It was quite a thunderstorm that evening and all of a sudden a flash of brilliant green blazed at one end in the sky. At that time it was obviously quite a shocker.
If you take the green bolt on the right & rotate it 180 degrees, it matches the features of the main bolt on the left like a fingerprint. This is an inverse reflection, possibly caused by having a filter on the end of the lens. I have at least 2 lightning photos where this has happened to me. pic.twitter.com/KNSVH21N5Y
This explination does not persuades me.
I suggest, that it is a phenomen of the Rayleigh-Scattering. Check it out !
Look out and you can see other colors as well. So .....
Prof. Walter Lewin expalins you more about on You Tube with his last lecture at MIT "For The Love Of Physics".
Thank you very much for your observation. I checked it out and: You are right !
It is actually a lens-flare.
Crigs from Berne, Switzerland
@Mario Chong Thank you!!!
@Andy Killgore A link to a post that better illustrates the reflection. https://www.facebook.com/photo.php?fbid=715465238464862&set=a.101654619845930.3971.100000041764285&type=1&theater¬if_t=like
@stephen salazar It was most likely a power transformer blowing. They can light the sky quite brilliantly.
@Mike Hall I like how you figured out a simple explanation for this while this scientist spent way too long forming hypotheses, and even had an article written. But what causes the reflection?
I wholeheartedly think so. the article's explanation is really disappointing. :(
In my opinion, Mie scattering mechanism can say a better answer. I think those volcanic ash particles are too large to make a good Rayleigh scattering. I heard that Mie scattering occurs when the particle is larger than 1/10 of the wavelength of the incident light. Just the size of ash particles~!
@Kevin Kang If it had not happened to some of my own lightning photos, I would've probably missed it. Lightning is my number 1 favorite subject to photograph.
It is actually a lens-flare.
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