Document Type

Article

Publication Date

1-20-2003

Publication Title

Applied Optics

Abstract

Coronas are simulated in color by use of the Mie scattering theory of light by small droplets through clouds of finite optical thickness embedded in a Rayleigh scattering atmosphere. The primary factors that affect color, visibility, and number of rings of coronas are droplet size, width of the size distribution, and cloud optical thickness. The color sequence of coronas and iridescence varies when the droplet radius is smaller than similar to6-mum. As radius increases to approximately 3.5 mum, new color bands appear at the center of the corona and fade as they move outward. As the radius continues to increase to similar to6 mum, successively more inner rings become fixed in the manner described by classical diffraction theory, while outer rings continue their outward migration. Wave clouds or rippled cloud segments produce the brightest and most vivid multiple ringed coronas and iridescence because their integrated drop size distributions along sunbeams are much narrower than in convective or stratiform clouds. The visibility of coronas and the appearance of the background sky vary with cloud optical depth tau. First the corona becomes visible as a white aureole in a blue sky when tau similar to 0.001. Color purity then rapidly increases to an almost flat maximum in the range 0.05less than or equal totauless than or equal to0.5 and then decreases, so coronas are almost completely washed out by a bright gray background when tau greater than or equal to 4. (C) 2003 Optical Society of America.

Original Citation

Gedzelman, Stanley D. and James A. Lock. "Simulating Coronas in Color." Applied Optics 42 (2003): 497-504.

DOI

10.1364/AO.42.000497

Version

Publisher's PDF

Volume

42

Issue

3

Included in

Physics Commons

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