Bad Astronomy

“Stormscapes”: Mesocyclone Time-Lapse

mesocyclone
What makes this eerie green-blue light emanating from mesocyclones?  

Photo by Nicolaus Wegner, from the video

What, a gorgeously shot series of mesocyclones and other storms recorded forming in a time-lapse video? Yeah, you know I want to show you that.

Those are amazing. They were shot by Nicolaus Wegner in 2013 in Wyoming. Mesocyclones are mesmerizing, and I’ve written about them many times before (and explained how they form). I’m still interested in the deep aquamarine color that sometimes appears, too. It’s not well understood.

Hypotheses abound, including light bouncing off hail, and somehow the red setting Sun contributing to the green color of the sky (presumably by contrast; they way our eyes perceive color depends quite strongly on what other colors are nearby).

I’m not exactly sure how you could figure out what causes it; tests in the field would be difficult given the circumstances. Perhaps a spectrum could be taken, and the various contributing factors teased out. Is the green light strongly polarized or not? That might also be a clue to how the color is generated.

At some point I’d love to dig into this further. It’s an interesting and puzzling problem, and those are the most fun kind.

Tip o’ the umbrella to the Rain Forest Site.