Hallo Ingo,
Die Aufklärung geht noch ein wenig weiter!
Hier ein Auszug aus Sky & Telescope (März 1989, p. 255):
Halo PhenomenaThe family of sky halos is enormous, and the most common members may appear dozens of times a year. Most are caused by
hexagonal ice crystals with
flat tops and bottoms reflecting or refracting light, usually in thin cirrus-type clouds. These simple crystals produce a great variety of halo effects, depending on their sizes, shapes, and orientations to the Sun and observer. In some ways the halos' beauty can rival that of the rainbow.
Dimmer and rarer is the 46° halo, but diligent observers can glimpse at least part of it on infrequent occasions. A whole family of phenomena may attend the
22° halo, and to a lesser extent the
46° halo. Most require the Sun to be the source of light; the Moon is too dim. One common feature of the 22° halo is strong color —
red on its sharp inner edge, bluish white on its fuzzy outer edge.
Fred Schaaf (1989) A Field Guide to Atmospheric Optics (Sky & Telescope, March 1989, pp. 254-259).
Herzliche Grüße,
Bernd
