The scattering effect
Vivid reddish, orange and violet colours have just appeared in the sky on sunset last night.
The phenomenon is called 'Scattering'. Because the sun is low on the horizon, sunlight passes through more air at sunset and sunrise than during the day. The atmosphere has combined with short-wavelength violet light that were scattered by molecules in the air, making the clouds look these colours to the human eye.
A summer sunset Waitemata Harbour 18th February