A Sun Halo Over Cambodia

Have you ever seen a halo around the Sun? This fairly common sight occurs when high thin clouds containing millions of tiny ice crystals cover much of the sky. Each ice crystal acts like a miniature lens . Because most of the crystals have a similar elongated hexagonal shape, light entering one crystal face and exiting through the opposing face refracts 22 degrees , which corresponds to the radius of the Sun halo . A similar Moon halo may be visible during the night. Pictured above , a nearly complete sun halo was photographed high above the ancient Bayon temple in Angkor , Cambodia . Exactly how ice-crystals form in clouds remains under investigation .