What optical phenomenon causes the luminous ring known as a lunar halo?
Answer
Refraction of moonlight through microscopic ice crystals
A lunar halo is fundamentally an optical demonstration of physics rooted in refraction. This occurs when moonlight interacts with microscopic ice crystals suspended in the atmosphere, typically found in high-level clouds. Unlike rainbows, which are produced by light scattering off water droplets, the halo requires light to enter one face of a six-sided crystal and exit another, causing the light to be bent, or refracted, consistently at a specific angle. This precise and uniform bending across countless crystals projects the distinct circular ring visible from the ground.
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Related Questions
What optical phenomenon causes the luminous ring known as a lunar halo?What precise minimum angle reflects light refraction by common hexagonal ice crystals in a lunar halo?Which specific types of high-level clouds produce the ice crystals necessary for a lunar halo?Approximately how many times the Moon's diameter must be stacked to span the $22^ ext{o}$ circle outward to the ring?What inherent geometric property of ice dictates the $22^ ext{o}$ minimum deviation angle for the halo?In mid-latitude areas, what weather condition often follows the appearance of a high-level lunar halo?For the $22^ ext{o}$ halo to form, what specific angle must the exit face be relative to the entry face of the hexagonal ice crystal?What observation suggests turbulence within the high cloud layer when viewing a lunar halo?Besides the $22^ ext{o}$ halo, what other, larger halo is sometimes produced by moonlight interacting with ice crystals?What angular span, measured by a fully stretched hand at arm's length, can help an observer estimate the $22^ ext{o}$ halo?