glory

An atmospheric optical phenomenon consisting of one or more series of iridescent rings that an observer can see around their own shadow, when it is projected onto a cloud composed exclusively of tiny water droplets. Occasionally, it can also be observed on snow and dew. It is the result of a backward scattering of the incident light on the droplets, in which reflection, refraction, and diffraction of the light combine. The angular diameter of the glory - much smaller than that of a rainbow - is inversely proportional to that of the droplets. The greater or lesser uniformity of the droplet sizes determines whether we see a single series of rings or several. The interference phenomena that occur as light diffracts around the edges of the object producing the shadow are responsible for the appearance of separate luminous bands. One of the situations in which we can observe a glory is when traveling by plane, when it flies over a sea of clouds. If the aircraft casts its shadow on that cloud layer, we will have a good chance of seeing the glory around it. The phenomenon is also known as the ring, circle, corona, or halo of Ulloa, in honor of the Spanish sailor Antonio de Ulloa (1716-1795), who was the first to carry out a scientific description of it. Since it is centered on the antisolar point, it is likewise called an anthelion.