A vague glory display was photographed over central Utah from an airplane beginning its descent through a cirrus cloud layer with an estimated cloud top temperature of -45 and -55 °C. Photographic analysis reveals a single reddish-brown ring of 2.5–3.0° radius around the antisolar point, although a second ring appeared visually to have been present over the brief observation period. Mie and approximate nonspherical theory scattering simulations predict a population of particles with modal diameters between 9 and 15 μm. Although it is concluded that multiple-ringed glories can be accounted for only through the backscattering of light from particles that are strictly spherical in shape, the poor glory colorization in this case could imply the presence of slightly aspherical ice particles. The location of this display over mountainous terrain suggests that it was generated by an orographic wave cloud, which we speculate produced numerous frozen cloud droplets that only gradually took on crystalline characteristics during growth.
© 1998 Optical Society of America
Kenneth Sassen, W. Patrick Arnott, Jennifer M. Barnett, and Steve Aulenbach, "Can Cirrus Clouds Produce Glories?," Appl. Opt. 37, 1427-1433 (1998)