Discover published sets by community

A rainbow is a meteorological phenomenon caused by reflection, refraction, and dispersion of light in water droplets resulting in a spectrum of light appearing in the sky. It takes the form of a multicoloured circular arc. Rainbows caused by sunlight always appear in the section of sky directly opposite the sun. The conditions required are the presence of water droplets and sunshine.

A halo is an optical phenomenon produced by ice crystals creating colored or white arcs and spots in the sky. Most halos appear as bright white or red rings around the sun or moon, but the most common are the 22° halos. Halos form when sunlight or moonlight is refracted in millions of hexagonal ice crystals suspended in the atmosphere.

A mirage is an optical illusion caused by the refraction of light that can make distant objects appear distorted, closer, or further away, or it can make it seem like there are pools of water on the ground. Mirage is typically observed on hot days when the ground is very warm. The warm air close to the surface is less dense than the layers of air above it, causing the refractive bending of light rays.

The Green Flash is a rare optical phenomenon that occurs briefly before sunrise or after sunset when a green spot is visible, usually for no more than a second or two, above the sun. The flash is caused by the refraction of light in the atmosphere: sunlight is dispersed into its spectral colors, and green is momentarily seen due to its position in the middle of the spectrum. The atmospheric conditions required include a clear, well-defined horizon and a stable atmosphere.