The Science of Rainbows: Understanding Spectral Phenomena

Rainbow Formation Explained
Rainbow Formation Explained
Rainbows are optical illusions caused by water droplets. Sunlight refracts within the droplets, then reflects internally and refracts again when exiting, splitting into a spectrum and forming a circular arc.
Colors of the Rainbow
Colors of the Rainbow
A rainbow typically displays seven colors. Red, orange, yellow, green, blue, indigo, and violet are seen due to different wavelengths of light bending at slightly different angles.
Rare Double Rainbows
Rare Double Rainbows
Double rainbows occur when light reflects twice inside water droplets. The secondary rainbow appears above the primary, with colors reversed and less vibrant due to the extra reflection.
Supernumerary Rainbow Bands
Supernumerary Rainbow Bands
Fainter, pastel bands called supernumerary rainbows can appear under a primary rainbow. They're formed by wave interference when sunlight strikes small, uniformly-sized droplets.
Twilight Red Rainbows
Twilight Red Rainbows
Red rainbows, called monochrome rainbows, happen at sunrise or sunset. The shorter blue wavelengths scatter away, leaving red hues dominating the arc.
Rainbows Aren't Just Arcs
Rainbows Aren't Just Arcs
The circular nature of rainbows often goes unnoticed because the ground obscures the lower part. From high vantage points, one can sometimes see the full circle.
Beyond Earthly Skies
Beyond Earthly Skies
Rainbows aren't exclusive to Earth. They potentially occur on any planet with sunlight and reflective moisture, but variations in atmospheric composition can alter their appearance.
Moonbow Mystery
Moonbow Mystery
Moonbows, or lunar rainbows, occur at night, created by moonlight refracting through droplets, appearing fainter and often white due to lower light intensity.
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What causes a rainbow's optical illusion?
Sunlight reflecting off mountains
Light in water droplets, refraction
Moonlight scattering in the rain