Twilight Sky. I've been asked "was it really that bright and colourful?" ~ Yes it was!

If the air scatters shorter wavelengths more efficiently than longer ones, why is clear sky not violet rather than blue? It appears so because sunlight does not contain much violet and the eye is not very sensitive to it.

Jan 26th 2003, sun's centre 3° below the horizon.
1/30s f/2.8 100 ISO equiv. 2 images each 35mm efl. Approximate FOV 75°
Photo ©2003 Les Cowley