Imaged by András Pintér at Mihályi, Hungary. A faint outer secondary bow is also visible. ©András Pintér
|Sunset and sunrise are special times for rainbows. With the proper spread of rain opposite the sun a complete semi-circular bow shows high in the sky.
Highly reddened sunset light suffuses the landscape and casts a narrow red hued rainbow with only traces of other colours.
The reddening is from scattering of sunlight by small dust particles and the air molecules themselves. The air scattering that gives us blue skies has its complement in sunset hues. Blues and greens are preferentially scattered from the long atmosperic path sunset rays to leave reddened light.