TAMPA, Fla. (WFLA) – Purple clouds graced the night sky in Florida on Wednesday after Hurricane Dorian moved up the coast, much to the delight of skywatchers.
Floridians shared stunning images of the sky, which appeared to turn an eerie purple after the storm passed through.
“Our little piece of Florida survived Hurricane Dorian and we were rewarded with this GORGEOUS purple sky tonight!!” a St. Augustine resident wrote in a post on Instagram.
As it turns out, there’s a scientific explanation for this phenomenon called “scattering.”
According to experts, scattering happens when hurricane clouds distort light from the sun.
“Scattering affects the color of light coming from the sky, but the details are determined by the wavelength of the light and the size of the particle,” University of Wisconsin-Madison scientists said in research published in Science Daily. “Because the sun is low on the horizon, sunlight passes through more air at sunset and sunrise than during the day, when the sun is higher in the sky. More atmosphere means more molecules to scatter the violet and blue light away from your eyes. If the path is long enough, all of the blue and violet light scatters out of your line of sight. The other colors continue on their way to your eyes. This is why sunsets are often yellow, orange, and red.”
The sky was also purple after Hurricane Michael. The sun had set low in the sky, giving its white sunlight extra space in the atmosphere, therefore more of the light was able to scatter before becoming visible to the eye.
“As sunlight shines down to Earth, most of the colors of the spectrum are able to reach the surface uninterrupted,” First Coast meteorologist Lauren Rautenkranz said an explainer video after Michael. “But the shorter wavelengths, blue and violet, are scattered in every direction. This light bounces from particle to particle until it eventually reaches your eyes.”
Rautenkranz added: “Since violet is the shortest wavelength of the spectrum, our sensitive eyes only detect blue. However, the violet is there and we saw it after Hurricane Michael, but why? In this case the air, was super saturated, we had dew points in the mid- and upper 70s [degrees Fahrenheit,] the sun was setting—so were losing daylight—and the hurricane’s clouds surrounded us, hanging low to the ground.”