If you are caught on a golf course during a storm and are afraid of lightning, hold up a 1-iron. Not even God can hit a 1-iron.

Lee Trevino, golfer who actually has been struck by lightning.

Today’s astronomy picture of the day is absolutely gorgeous.

Of course, this is the Icelandic volcano, Eyjafjallajökull, erupting and spewing up volcanic ash. But, of course, the most interesting part of this picture is the lightning, which looks like it both originates and ends in the Volcanic ash itself!

Image credit for both images above: Marco Fulle, via helicopter.

First off, I’d like to be concrete about this. The way it looks — that the lightning originates in the volcanic ash — is exactly the way it is! This isn’t some “lucky shot” by a photographer, either. Check out this picture of Eyjafjallajökull from April 17th.

Image credit: Snaevarr Gudmundsson, through Universe Today.

Is it just this volcano? Eyjafjallajökull, it turns out, is not remarkable at all for having volcanic lightning. If we look at some other major recent eruptions, we can see volcanic lightning in the ash there as well. Here’s Chile’s Chaitin volcano, from its 2008 eruption.

Image courtesy of National Geographic.

And here’s another one: Sakurajima, from its eruption in 1991.

Image credit: Sakurajima Volcananological Observatory.

All told, there have been more than 150 different eruptions over the past couple of centuries where volcanic lightning has been recorded. In fact, I’ve managed to dig up some photographs of volcanic lightning from before I was born! Here’s Mount Vesuvius — and the accompanying volcanic lightning — from 1944!

Courtesy of an old tripod.com website.

Okay, so now you’re convinced that lightning happens in volcanic ash all the time. Yes, it makes for a spectacular picture, but how do you get this in the first place?

Well, what is lightning? You create a big enough electric potential difference between two places, and you can get all of these excess charges to “jump down” to the lower potential. In air, it takes a voltage of about 33,000 Volts (!) to get a spark to jump even one centimeter! Lightning that goes from a high cloud down to the ground can have a voltage difference in excess of a billion Volts!

You can do this because you can get a huge amount of charge separation. For example, in a big lightning strike, you separate out about 1020 electrons! But ash and rocks — even molten rock — are electrically neutral, right? So how to we get a big voltage from neutral matter?

Thankfully, the ash that comes out is hot enough so that not every particle is neutral: many are positively charged ions and many are negatively charged ions.

If you can make something push the positive ions differently than it pushes the negative ones, you can create a charge separation! If you get enough charges separated, you can make a large enough voltage to give you lightning!

This should be easy, because when you get charged particles moving around, you make electric and magnetic fields, which is exactly the ingredient you need to separate these charges. As long as these fields are here, differently charged ions are doomed to separate away from one another! And as soon as you get a large enough charge accumulated in different parts of the sky, that’s the tipping point, and then you get lightning!

And for those of you who like details with your pretty pictures and explanations, there is some uncertainty as to the exact mechanism that gives you this separation of charge. (Some ideas are here, and some research into the topic is available here.) But this really is lightning from within the volcanic ash! It certainly makes for quite a show, so enjoy it, but enjoy it from a safe distance!

Update: This page has been translated into Romanian!


  1. #1 waynerobinson4
    April 20, 2010

    Good article. It explains something that had perplexed me; why the 3 people who died of a lightning strike during the eruption of the Paricutin volcano in Mexico (the only volcano whose entire life history has been documented by eyewitnesses) were ascribed to the eruption and not a co-incidental storm.

  2. #2 teraafirma
    April 20, 2010

    ……..and i believe this ash has benefits too?

  3. #3 Todd Tomlinson
    April 20, 2010

    I was near the base of Mt. St. Helens the morning of May 18th when it erupted. It was an incredible site to be that close and to be able to see the lightening in the ash cloud. Great pictures!

  4. #4 Tim Kirk
    April 20, 2010

    Interestingly the BBC report about a plane that lost all 4 engines a decade or so ago flying through a volcanic plume, and is one reason why all the flights are stopped over much of northern Europe, mentioned the spectacular show of St Elmo’s fire set off by flying through the cloud. (The engines did eventually restart after the plane had lost 3/4trs of its initial altitude and everyone landed safely).

  5. #5 Mani Karna
    April 20, 2010

    Thanks for explaining the thing out. On first view i was thinking this could be another one of those spooky government activities.

  6. #6 ICP CLOWN
    April 20, 2010

    Fark scientists, you’re motherfarking liars.

    EXPLAIN MAGNETS. You can’t.

  7. #7 Munir
    April 20, 2010

    Nature is amazing, and studying it always makes it more interesting.
    Thanks for sharing such a nice info

  8. #8 zeke
    April 20, 2010


    While some of the most fertile soils can be found around volcanoes, this stuff from Eyja isn’t so great. It has lots of fluoride salts which is toxic to vegetation and animal life. Icelandic volcanoes also emit lots of hydrogen fluoride which is an extremely corrosive acid.


  9. #9 anon4
    April 20, 2010

    Any Hi-Res (1940×1600) images I can use for wallpaper?

  10. #10 Keith Harwood
    April 21, 2010

    If I remember correctly, Pliny described lightening at the 79AD eruption of Vesuvius.

  11. #11 travc
    April 21, 2010

    There is an episode of the TV show “Air Emergency” (NatGeo channel) about the incident with BA009 in 1984 unwittingly flying through an ash cloud. Amazing stuff. The plane was enveloped by a sort of Saint Elmo’s fire and was basically sandblasted. May be some clips online.

    Icelandic volcanoes generate HF?!? “Extremely corrosive” doesn’t even come close to conveying how scary that stuff is.

  12. #12 tret
    April 21, 2010

    @11 (@8)
    “Corrosiveness” as a measure of acidity has actual, literal, extremes. The “most corrosive” acid would be at that extreme, 0 pH. You can’t go beyond the extreme here, like you could at the edge of a cliff.

  13. #13 daedalus2u
    April 21, 2010

    Tret #12, corrosiveness is not just determined by pH, the ability to form complex ions is perhaps a little more important than the pH. HF is corrosive because it forms lots of fluoride complexes with metals and can attack oxides. HF does attack glass, not because of pH but because it forms H2SiF6. Low pH doesn’t attack glass because SiO2 isn’t attacked by it. A useful way of making chemical glassware more chemically resistant is to leach them with HCl. That leaches out the cations from the glass, leaving a layer of pure SiO2. If you then rinse and dry the glassware at a high temperature that porous layer collapses into a pure SiO2 layer that is more resistant to leaching in acid.

    Citric acid is a good complexing agent and so if you mix citric acid with just about anything else it becomes more corrosive. Salt water is corrosive because of the complexing ability of the chloride ion, not because of the pH.

  14. #14 Ros
    April 22, 2010

    Thank you so much for this – explains it in a way I can use in my classroom of primary school pupils. I really appreciate it.

  15. #15 Mary Davis
    April 22, 2010

    Indeed very interesting, thanx for sharing!

  16. #16 Marco
    April 22, 2010

    Notable artículo

    muy buena explicación sobre los rayos y la separación de las cargas atómicas

  17. #17 Sphere Coupler
    April 22, 2010

    It is odd how something so blatant like lightning can not be understood by Academia due to political correctness, when the common man has understood for many years.

    It’s probably a good thing for evolution that the individual only last for 100 years, so that petty rivalries can be forgotten!

    I think the powers that be, are scared that the public can not handle the truth, maybe true…but still sad.

    Or just maybe this is one of those unspoken truths that each individual will have to discover on their own.

    And when Academia does figure it out, I seriously doubt that the proper credit will be attributed.

    The knowledge is there…it’s just obscured.

    *in a cynical mood tonight*

  18. #18 Rob Mills
    April 23, 2010

    LOL @ ICP CLOWN!! Thank-you so much for making me laugh my ass off for a long time. Also I posted your comment on my facebook so all my friends could laugh at you as well.. Your absolute STUPIDITY has made my day!!. Thank-you so much, moron! Please don’t ever change.

  19. #19 Paul Metting
    April 23, 2010

    I like your explanation, thank you for sharing it. I witnessed Mount Pinatubo erupting, from 8 miles away. I stood on my back porch and observed orange lightning in the roiling ash.

  20. #20 rijkswaanvijand
    April 24, 2010

    Eyjafjallajökull is a glacier, not a volcano!

  21. #21 Anthony
    April 25, 2010

    Great explanation; I never knew that!

    Have a great day

  22. #22 hanzel
    April 27, 2010

    Nice collection! The 3rd image the lightning over the volcano is so amazing but at the same time is so scary…

  23. #23 Johann
    May 18, 2010

    In your article you wrote:
    You create a big enough electric potential difference between two places, and you can get all of these excess charges to “jump down” to the lower potential.

    To be theoretically correct, shouldn’t this read: “you can get all of these excess charges to “jump up” to the higher potential” as the excess charges jumping are electrons (minus charges)?

    The graphic series “charge separation form in ash cloud” supports my question 🙂

  24. #24 Robert
    May 20, 2010

    To Rob Mills: the poster listed as “ICP Clown” managed to hoax you a bit. Elsewhere on the internet, the phrase “f**king magnets, how do they work?” is rather well known. Two rappers known as Insane Clown Posse created a video for their latest release, “Miracles”, and at about 1:52 in the video one of the rappers relates that he does not understand how magnets work, but he won’t ask a scientist, because scientists are reknowned liars. See more here: http://knowyourmeme.com/memes/f-cking-magnets-how-do-they-work

    I laughed for different reasons at ICP Clown’s post; a rather well constructed proliferation of a meme.

  25. #25 alejandro
    August 19, 2010

    holy craps those pix are so tight

  26. #26 mimi
    September 1, 2010

    thats so cool i never knew lightning came out of volcanoes
    totaly awsome!!!

  27. #27 dev
    November 18, 2010

    super gorgeous images. the shot of Eyjafjallajökull is super magic. thank you for posting these

  28. #28 andrei
    November 26, 2010

    people has a good conduktor,why is one people has nakurentihan and the 2 to 3 people hold the 1 people the bulb wiil light why?

  29. #29 Kristen Gallig
    December 9, 2010

    I think that these pictures r very reasuring, that our volcano ejall, is a awesome volcano

  30. #30 science
    January 30, 2011

    Eyjafjallajökull is stunning

    and scary

  31. #31 TeslaCoilGirl
    January 30, 2011

    😛 I knew abt this but these are nice shots! I thought it was 10Kv to a centimeter (according tot mythbusters)

  32. #32 steven
    February 18, 2011

    f!ck thats gay

  33. #33 cnocspeireag
    March 14, 2011

    Nice explanation Daedalus2U. I always hated using HF as it’s so toxic and horrible.
    You might also mention that it is possible to have negative pH,or ‘stronger’ acid than zero even in aqueous solution, but this isn’t demonstrable using glass electrodes.

  34. #34 ok
    May 14, 2011

    I want to have sex with one of you guys

  35. #35 josh
    May 18, 2011

    hey man you got some really cool stuff on here its really interesting. good job

  36. #36 Li Ray
    June 12, 2011

    Who ever wrote this article please beware God can hit a needle’s eye with lighting and also strike remorse in your heart!

  37. #37 Ron
    August 1, 2011

    How can I get a copy of one of these pictures

  38. #38 ambisinistrous
    August 25, 2011

    Li Ray – I believe in god as well but I think this is one of those times you should hold your comment. Seriously. If god is dropping the bolts of lightning that descend from the sky, then who is shooting lightning out of volcanoes? Satan? Grow up. Religion and science can coexist.

    Oh yeah, and by the by, I was once struck with remorse in my heart….. it was a chemical reaction between Taco Bell and a 12 pack of Natty Light. Evil science.

  39. #39 fdhsja
    December 1, 2011

    Sexy wolveriene pic broski

  40. #40 Amitava Manna
    October 22, 2012

    I burned off interest in science as I am growing old. But nevertheless I enjoyed the article.

  41. #41 Robert
    United States
    October 29, 2012

    Hey I’m having a science fair soon, I was hoping to “re-create” the lighting that comes from the ashed by air pumping the ash/dust up in a plastic to and try to get a read of how many volts it makes, is this possible or is it a bad idea some what? please help.

  42. #42 Hanieh
    February 14, 2013

    very good…thank you

  43. #43 Nicole
    United Kingdom
    May 10, 2013

    I have found one of your pictures of lightning on Google and I would love to use one of them in my GCSE course work for school . I would like your permission to use it. If you would like to contact me please use my email address; nicoletattersall@hotmail.co.uk. Thank you.

  44. #44 bob
    May 19, 2015

    @20, technically it is both the name of a glacier and the volcano, but Eyjajokullfjalla is completely cover by an ice cap.
    @13, good explaination.

  45. #45 bob
    May 19, 2015


  46. #46 Marion den Boer
    Dordrecht, Netherland
    September 30, 2015

    I am writing a book about my husband who had a brainstroke on a ship. I looked for a picture whith lightning on water and I found one on your site.Can I please have your permission to use your picture on the cover of my book?

  47. #47 Mary Ellen Allison
    NJ, USA
    February 19, 2016

    I love the picture of the blue lighting (labeled Lightning 1). I am directing a college production of MACBETH and would love to use it on our poster. Please email me at mallison@ramapo.edu.

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