A “lunar halo” spotted in Villeneuve-les-Avignon
Congratulations to Adrian Four! Geographer and student in M2 Management of Disasters and Natural Risks, the Gardois alerted France Bleu Gard Lozère of a surprising weather phenomenon this weekend. He also managed to photograph this moment and capture a “lunar halo” in the sky of Villeneuve-les-Avignon. The phenomenon occurs when the Moon is quite low on the horizon and the atmosphere is laden with ice crystals present in high-altitude clouds called cirrus or cirrostratus, according to the “Sky Misunderstandings” website:Crystals naturally forming in clouds follow a hexagonal symmetry, taking the shape of an elongated prism, or alternatively a flattened hexagon or six-pointed star. During their fall, these particles, which have angles all equal to 60° or 120°, can spontaneously orient themselves horizontally and form a network of prisms which reflect and refract sunlight. When the light passes through crystals between faces forming an angle of 60° between them, the minimum deviation is 22°, conditioning the apparent dimension of the main halo, or small halo.”