"On May 15th, I was in my garden, surrounded by the quietness of the Sicilian countryside, when, lifting my eyes to the sky, I saw an extraordinary halo display," says Pace. "With my camera in hand, I began running along the country road beside my home, searching for an open field that could reveal the entire composition."
The luminous network included a circumzenithal arc, a supralateral arc, a suncave Parry arc, an upper tangent arc, a 22° halo, a parhelic circle and a sundog.
"As I ran, the complex display kept transforming before my eyes," says Pace. "The greatest surprise came when I saw a Parry arc forming above the upper tangent arc--the rarest phenomenon of all!"
Suncave Parry arcs are exceptionally rare because they require sunlight to pass through column-shaped ice crystals suspended in a very specific, improbable, and unstable alignment in the atmosphere. They were first recorded in 1820 by William Edward Parry while icebound off Melville Island in the Canadian Arctic.
"The entire spectacle lasted only twenty minutes," she says. "Then thicker clouds slowly advanced, covering the sun and dissolving one by one all the arcs that had transformed my sky into a mosaic of light and ice."
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