DALLAS — Was Anna being invaded by extraterrestrial life this week?
Probably not.
Still, our friends in Anna got quite the shock on Thursday evening when a bright green spot in the sky was spotted ahead of severe weather in the region.
Check it out from multiple angles:
Wild stuff, right?
So... what was it?
Can severe weather cause the sky to turn green? Yes!
My fellow "Twister" fans -- it's the greatest movie of all time, and no objections will be heard-- may remember the part of the move where the late, great Bill Paxton stares off into the distance, analyzes impending severe weather and notes that the sky is "going green."
“Greenage!” the also late and great Philip Seymour Hoffman replies enthusiastically.
During intense thunderstorms like we had on Thursday, the presence of large, and lots of, hail can lead to the mesmerizing phenomenon of green skies -- or "greenage" as Philip Seymour Hoffman's Dusty character calls it.
This peculiar optical effect happens because of the interaction and scattering of sunlight with all of the water and ice that's suspended in the air by the intense updrafts of these supercell thunderstorms. When sunlight passes through the hail, the shorter blue and green wavelengths get scattered more effectively than the longer red wavelengths. As a consequence, the blue and green colors dominate the scattered light, giving rise to the distinct green hue that colors the sky.
This scattering is known as Rayleigh scattering. It’s the same process responsible for the blue color of the sky on a clear day. During severe weather events with hail, however, the presence of big chunks of ice alters the scattering process, leading to an unusual greenish appearance of the sky.
The intensity of the green coloration can vary depending on factors such as the size, volume and density of the hail, the angle of sunlight and the overall composition of the atmosphere. In some cases, the green skies may appear more subtle. In other cases it can be vivid and striking, creating a surreal and captivating visual.
While green skies during severe weather are relatively rare, they are certainly not unheard of.
Alas -- and perhaps unfortunately -- this wasn't that.
The simple answer behind this weird light? A lit-up water tower
As much as I wish that I had an exciting, science-y explanation for you, the honest-to-goodness answer here is a lot simpler.
Ready for it?
The City of Anna has been lighting up its water tower in green this week. The light in the clouds that curious and observant WFAA viewers sent our way was, quite simply, that light reflecting off the base of the clouds.
That's all.
Sorry to be the party pooper.
Here's some photo evidence from the City of Anna themselves of their water tower being all lit up:
Ever heard of Occam's razor? In philosophy, it's the adage that suggests the easiest answer is usually the best one. Which, in this case, worked out!
Why was the sky green in Anna on Thursday? Because humans made it so.
Still, I hope you learned something today! Light refraction -- just as lighting in general, I suppose -- is pretty neat.
