Circumhorizon Arc Captured over Samosir Island, Indonesia

Photographer: Epifania Di GabrieleSummary Author: Epifania Di GabrieleThe photo above showing a colorful strip in the sky over Samosir Island and Toba Lake, Sumatra was captured at approximately 12:50 p.m. local time on July 7, 2024. This eye-catching optical phenomenon is called a cicumhorizon arc. These arcs can be observed anywhere that the Sun attains an elevation of at least 58 degrees. In the mid latitudes, this means they can only be detected a month or so on either side of the summer solstice but even then, only near the noon hour. They form when sunlight is refracted and dispersed through hexagonal plate ice crystals, found in cirrus type clouds -- sunlight enters one of the horizontally oriented side faces of these crystals and exits through the bottom plate.

 

Samosir Island, Toba Lake, Sumatra, Indonesia Coordinates: 2.68, 98.88

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