Abstract

Using a Monte Carlo method, we traced many paths of sun rays through a population of ice crystals. The sun rays are scattered diffractively (in Fraunhofer approximation) or refractively without internal reflections (in geometrical optics approximation). In this way we produce point plots representing the intensity of diffraction structures around the sun, the 22° - parhelia, and the the 22°-halo for specified populations of ice crystals. By simulation of two halo displays with cross-like and disk-like diffraction structures around the sun, we obtain a mean diameter of 40 µm for well oriented ice crystals, and 10 µm for randomly oriented ice crystals.

© 1990 Optical Society of America