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The arc of fog with the Brocken spectrum is an unusual meteorological phenomenon, difficult to photograph and much more so in the summer, but it has been seen in Vilanova de Sau, as can be seen in this report in Las Fotos de los Lectores de La Vanguard.
The Brocken spectrum has the colors of the rainbow but inverted, while the arc of fog is white or with very weak colors and can form, as on this occasion, around the spectrum.
When the fog disperses and with the sun behind us, this arc is sometimes formed. It's like a rainbow but white. It is not usual for it to occur in summer, since it is more favorable for it to form at other times of the year, such as autumn.
The reason why it is called the Brocken spectrum can be found in Germany, where, as in the Catalan region of Osona, frequent fog occurs on the Brocken, a peak of the Harz mountains.
The Brocken specter was observed and described by Johann Silberschlag in 1780. Since then, it has often been recorded in German literature when talking about, for example, the devil and witches.
