Probleme der kosmischen Physik

THOSE who are interested in the optical phenomena of the earth's atmosphere have reason to be grateful to the editors of this valuable series of monographs, for, at no long interval after “Die Dammerungserscheinungen”, has appeared this volume dealing with the luminous rings, arcs, and patches, always beautiful and sometimes remarkably impressive, which are due to refraction and reflection of light by ice crystals suspended in the atmosphere. That these phenomena, which usually receive the general designation of halo, were due to ice crystals was suggested more than two centuries ago, and though the classical memoir by Bravais in 1847 admirably surveyed the knowledge of the time and, for certain phenomena, elaborated explanations which have required no essential modification, there are a number of matters which remain obscure at the present day. The halo of 22° and the associated parhelia (mock suns or sundogs) are the most frequently observed of halo phenomena and are well known to even the casual observer; but there are several other less common manifestations, the occurrence or form of some of which depends on the altitude of the sun (or moon), and there is as yet no unanimity of opinion as to the precise mode of origin of certain forms. On the other hand, the general theory of haloes indicates the possibility of other and as yet unrecorded forms. Probleme der kosmischen Physik . Prof. Dr. Christian Jensen Prof. Dr. Arnold Schwassman. Band 12: Die Haloerscheinungen . Von Prof. Dr. Rudolf Meyer. Pp. viii + 168 + 2 Tafeln. (Hamburg: Henri Grand, 1929.) 11 gold marks.