Erupting Volcano Photo Erupting on the Internet

Well, this is just cool. A picture's worth a thousand words, they say. I don't think I can come up with the words. But I have a question: "How did a volcanic eruption generate what looks like lightning in the sky?" Science never was my strong suit, but I did take a couple of meteorology classes. Still, I can't figure it out. Regardless, the photo is awesome and needed to be shared. Enjoy!