Phenomenon in which an arc of colours of the spectrum results from the double reflection and refraction of the Sun's rays by water droplets in the atmosphere. A primary bow is seen at a limiting angle of 42° to the observer's shadow. A secondary bow, at 51°, may occur; as can multiple bows due to some light being reflected within the raindrops before refraction. The colour separation in the primary bow produces a spectrum (violet, indigo, blue, green, yellow, orange, and red) with red on the outer edge. The colours are reversed in the secondary (outer) bow. The colour and intensity vary with the size of raindrops, large drops producing bright colours dominated by red.
Subjects: Meteorology and Climatology.