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‘Upside-down rainbow’ spotted in central Taiwan

Taichung resident shares photo after being mesmerized by rare optical phenomenon in sky

Rare optical phenomenon observed in Taichung Jan. 6. (Facebook photo)

Rare optical phenomenon observed in Taichung Jan. 6. (Facebook photo)

TAIPEI (Taiwan News) — A Taiwanese citizen surnamed Chen (陳) captured a photograph of an upside-down rainbow in the Taichung sky Monday morning (Jan. 6) and decided to share the rare sight with the public.

According to Chen, he came across the unusual rainbow in Dongshi District while on his way to work. He said that this was the first time he had observed such a phenomenon and that he was amused by the "smile in the sky."

The Central Weather Bureau's (CWB) Taichung Weather Station said that the "upside-down rainbow" is known as a circumzenithal arc, and despite being similar in appearance to a rainbow, it is actually produced by the sun interacting with ice crystals suspended in the atmosphere rather than by light refracting through raindrops, reported Liberty Times.

The weather station explained that the optical phenomenon seldom occurs in Taiwan due to the island's warm climate, but it is very common in countries and regions at high latitudes, such as Canada and the U.S. state of Alaska. Its solar halo appears visibly lighter than that of rainbows and is parallel to the horizon at the altitude of the sun.