Friday, September 6, 2019

Did Hurricane Dorian turn the sky purple up and down the East Coast?

By John Roach, AccuWeather staff writer




If the Twitterverse is to be believed, the sky over parts of Florida and the East Coast turned purple after Hurricane Dorian cleared out. Twitter was full of users posting purple-sky photos.
Mercedes Garcia wrote, “The storm left us this … a beautiful purple sky.”
Emory Cook posted, “The sky was literally purple tonight, very cool post-hurricane effect.”
And Amy Pope-Latham asked, “Do you think there’s a chance Dorian was a fan of Prince?”
The phenomenon was seen as far north as Maryland on Thursday evening, where Dorian's clouds were reaching at the time.
If indeed the “sky was all purple,” as Prince sang. But some AccuWeather meteorologists who looked at the photos were skeptical.
“It doesn’t look right,” said one meteorologist.
There were questions about whether people were using filters to make the sky look purple. “For what it’s worth, you can kind of see almost a purple tint to things in the pictures, not just sky,” said another. “I will say this, though -- there were a lot of different pictures and they were taken by different people, so not everybody is out there playing around with filters.”
There is some weather science to the purple sky. “It’s the scattering of the light that’s causing the refraction that causes the colors to look that way,” said AccuWeather Senior Hurricane Expert Dan Kottlowski. “I don’t know if that has anything to do with the hurricane.”
Molecules and small particles in the atmosphere change the direction of light rays, causing them to scatter, Steven Ackerman, professor of meteorology at UW-Madison told ScienceDaily.com.
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, he noted. The short-wavelength blue and violet are scattered by molecules in the air much more than other colors of the spectrum. This is why blue and violet light reach our eyes from all directions on a clear day, according to Ackerman, but because we can’t see violet very well, the sky appears blue.
It appears in this case, though, purple reigned. Or did it?
“It’s like the Purple Squirrel,” said another skeptical meteorologist, referring to a Pennsylvania critter that also caused doubts around AccuWeather.
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Seven years ago, there was a story about a Pennsylvania couple who trapped a purple squirrel when they were trying to keep birds at their feeders safe. Connie Emert said she had spotted the squirrel on her property but no one believed her, until it was caught.
“I kept telling my husband I saw a purple one out in the yard. ‘Oh sure you did,’ he kept telling me,” she said. “Well, he checked the trap around noon on Sunday and sure enough, there it was.”
The squirrel was later released into the wild.
As for the purple sky, similar purple skies were seen after Hurricanes Florence and Michael. Maybe Jimi Hendrix wasn’t the only one seeing “Purple haze all around,” after all.

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