Glory (optical phenomenon)

A glory is an optical phenomenon, resembling an iconic saint's halo around the shadow of the observer's head, caused by sunlight or (more rarely) moonlight interacting with the tiny water droplets that comprise mist or clouds.

"[1][4] Like a rainbow, outdoor glories are centred on the antisolar (or, in case of the moon, antilunar) point, which coincides with the shadow of the observer's head.

Before the first reports of the phenomenon in Europe, two members of the French Geodesic Mission to the Equator, Antonio de Ulloa and Pierre Bouguer, reported that while walking near the summit of the Pambamarca mountain, in the Ecuadorian Andes, they saw their shadows projected on a lower-lying cloud, with a circular "halo or glory" around the shadow of the observer's head.

[8] Ulloa reported that the glories were surrounded by a larger ring of white light, which would today be called a fog bow.

On other occasions, he observed arches of white light formed by reflected moonlight, whose explanation is unknown but which may have been related to ice-crystal halos.

[10][11] A summary of rainbowlike phenomena was provided in Scientific American in 1977, and states: It is gratifying to discover in the elegant but seemingly abstract theory of complex angular momentum an explanation for these two natural phenomena [Glories and 10th order Rainbows], and to find there an unexpected link between them.Most 20th century work on the phenomenon of rainbows and glories has focused on determining the correct intensity of light at each point in the phenomenon, which does require quantum theories.

Inspired by the impressive sight, he decided to build a device for creating clouds in the laboratory, so that he could make a synthetic, small-scale glory.

His work led directly to the cloud chamber, a device for detecting ionizing radiation for which he and Arthur Compton received the Nobel Prize for Physics in 1927.

Glory around the shadow of a plane. The position of the glory's centre shows that the observer was in front of the wings.
A solar glory and Brocken spectre
Illustration from Jorge Juan 's and Antonio de Ulloa 's, Voyage to South America (1748), depicting three separate scenes: (1) on the left, an erupting volcano; (2) on the upper right, optical glories surrounded by a fog bow ; and (3) on the lower right, arcs of white light near a mountaintop
A solar glory and Brocken spectre from Crib Goch in 2008