Rainbow formed of the fact that sunlight is refracted in the drops of water (rain or fog), which hover in space. Droplets are differentially deflecting light of the full range of colors (purple is rejected at 139 ° 20 ‘, red – 137 ° 30’).
As a result, white light can be decomposed into a spectrum. Observed this phenomenon seems to be in space in concentric arcs are multicolored glow. This happens only if the source of bright light is behind the person.