Noncircular glories and their relationship to cloud droplet size

Abstract

The atmospheric glory caused by backscattering of sunlight from clouds usually has circular colored rings. However, glories with noncircular rings are frequently observed, especially along the edges of clouds. Noting that the angular radius of the rings of glories is a sensitive indicator of the size of the water droplets in clouds, several images of glories have been examined in an attempt to explain the formation of noncircular glories.

Simultaneous observation of a glory and in-situ microphysical cloud properties

“…Appearing as colored concentric rings surrounding the shadow of the observer, it is caused by backscattering of sunlight from clouds. This phenomenon has been the subject of intense interest and study for several decades through laboratory experiments, field observations [1][2][3] and numerical simulations [4][5][6][7][8]. For theoretical considerations and various hypotheses about the formation of glories, readers are referred to [9][10][11][12][13][14][15][16][17].…”

Deriving cloud microphysics from radiometric measurements in the Amazon Basin

“…The angular position of the bows can be accurately described by the Mie theory given basic properties such as droplet size, refractive index, and wavelength, although a full account of the physics behind the phenomenon has been accomplished only recently (Nussenzveig, , ). From Mie scattering simulations of glory bows it has been possible to retrieve droplet effective radii ( r eff ) in naturally occurring warm clouds (Laven, , ) and the standard deviation in their distribution (Mayer et al , ).…”

“…Consistently, when the observer is above a uniform cloud, glory bows are circular and the droplets have retrieved sizes with narrow distributions (Mayer et al , ). On the other hand, when the cloud is observed obliquely, one can have r eff values varying from cloud base to top, or a superposition of parts of different clouds, resulting in distorted glory bows (Laven, ). Non‐circular bows can be analyzed to infer r eff as discussed by Laven ().…”

“…On the other hand, when the cloud is observed obliquely, one can have r eff values varying from cloud base to top, or a superposition of parts of different clouds, resulting in distorted glory bows (Laven, ). Non‐circular bows can be analyzed to infer r eff as discussed by Laven (). Thus, while non‐uniform droplet size distributions may require extra calculation steps, they do not prevent accurate glory retrievals.…”