An optical phenomenon that appears as an arc of the colours of the spectrum across the sky when falling water droplets are illuminated by sunlight from behind the observer. The colours are produced by the refraction and internal reflection of the sunlight by the water drops. Two bows may be visible, the inner ring being known as the primary bow and the outer, in which the colours are reversed, as the secondary bow.
Rainbow.
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.
- civil wars, French
- civil wars, Roman
- civil year
- CIX
- Cixi (1834–1908)
- Cixous, Hélène (1937–)
- CJD
- CKD
- CL20
- cladding
- clade
- cladism
- cladistic analysis
- cladistics
- cladode
- cladogenesis
- cladogram
- cladophyll
- Cladoselache
- Cladoselachiformes
- claimant
- Clairaut, Alexis Claude
- Clairaut, Alexis Claude (1713–65)
- clairvoyance
- Claisen condensation