Double rainbow seen over parts of Long Island, New York City

Ever hear of a souvlaki rainbow? No? That’s because it’s not a real thing.

But one member of the Cathedral of St. Paul in Hempstead coined the term when a double rainbow appeared over the church’s annual Greek festival.

“Everyone catch the rainbow over the Souvlaki pit? It was even double!” Paul Polichronakis wrote on Facebook, using the hashtag #souvlakirainbow.

At approximately 8 p.m., a double rainbow could be seen from New Jersey to Long Island. After a day of pounding rain, the rainbow stretched across the Manhattan skyline, as seen in photos posted on Twitter, Facebook and Instagram. Some called it “breathtaking” and “incredible.”

“It’s not just a rainbow; it’s a double rainbow,” leedlebug7 wrote on Instagram, using the hashtag #mylifeiscomplete.

“Pictures do not do this justice. The most vivid double rainbow I’ve ever seen in full display. Mother Nature put on a show for us tonight,” Ruby Lau wrote on Instagram.

One Newsday employee was driving along the Long Island Expressway when she noticed the rainbow. Drivers slowed down to admire it and some pulled over to take pictures.

A double rainbow is actually an optical phenomenon caused by a second reflection inside a water droplet, according to nasa.gov. "This 're-reflected' light exits the drop at a different angle. ... This is why the secondary rainbow appears above the primary rainbow," NASA's site explains.

And, it adds, you'll notice that the secondary rainbow will have the order of colors reversed, with red on the bottom and violet on the top.

With Tara Conry