Light scattering by ice hexagonal tubes calculated within the geometrical optics approximation

Abstract

Among the ice crystals of cirrus clouds, there are crystals of irregular shape. The imperfection of ice crystals can be both internal (e.g. inclusions such as air bubbles or soot particles) and external (e.g. surface roughness). Advanced studies showed that these imperfections have to be taken into account, because they affect significantly on the single-scattering properties of the ice crystal. The paper presents a solution to the problem of light scattering on ice crystal hexagonal tubes. This particle shape is the simplest model of a particle with internal inclusions. The model was based on the most common shape of a crystal observed in cirrus clouds -a hexagonal column with a ratio of base diameter to height of 0.69, in which a through hole was made, with a variable geometry. The solution was obtained within the geometrical optics approximation for the refractive index of ice 1.3116. The optical characteristics of hexagonal tubes are compared with non-convex particles (hollow columns) available in the database.