title: Intensity distribution of the parhelic circle and embedded parhelia at zero solar elevation: theory and experiments.
abstract: We describe the individual contributions to the intensity distribution of the parhelic circle for plate-oriented hexagonal crystals at exactly zero solar elevation using geometrical optics. An experimental as well as theoretical study of in-plane ray paths provides details on the mechanism for several halos, including the parhelia, the 120° and 90° parhelia, a blue edge, and the Liljequist parhelia. Azimuthal coordinates for associated characteristic features in the intensity distribution are compared with experimental data obtained using a spinning hexagonal glass prism.
authors.forename: Sarah
authors.initials: S
authors.lastname: Borchardt
authors.forename: Markus
authors.initials: M
authors.lastname: Selmke