Sheet 19820112

Type: Negative, Digital

Color: Black & White

Country: Switzerland

Region: Zürich

Date: Feb 2, 1982

$Image of sheet 19820112 photo 13: Lichtkreis um Mond Halo 'Dampfring' Weinbergstrasse 84 Zürich 1982 √ Halo (Singular der Halo; Plural Halos oder Halogone) ist ein Sammelbegriff für Lichteffekte der atmosphärischen Optik, die durch Reflexion und Brechung von Licht an Eiskristallen entstehen. A 22° halo is a halo, one type of optical phenomenon, forming a circle 22° around the sun, or occasionally the moon. It forms as sunlight is refracted in hexagonal ice crystals suspended in the atmosphere. As the light beam passes through two sides of the prism forming a 60° angle, the angle of minimum deviation is almost 22° (namely, 21.84° on average; 21.54° for red and 22.37° for blue). This wavelength-dependent variation in refraction causes the inner edge of the circle to be reddish while the outer edge is bluish. A 22° halo may be visible on as many as 100 days per year. copyright by Olivia Heussler$