Yesterday I took this wonderfully colourful spectrum of the direct bright sunlight and the less colourful one of the diffuse sunlight. Today after coming home from work I wondered how sunset would affect the spectrum. So here is the bright sun from yesterday:
And here is the situation tonight at 7:23 p.m. Sun is almost behind horizon. The yellow is gone and the red is only a shadow of its former self:
7:39 p.m. - 16 minutes later. The sun is below the horizon. Only diffuse light left. Some white clouds, some blue sky. My eyes still recognise a lot of colours outside but in my spectrum only blues and greens persist. If you look closely you might see a tiny little bit red:
7:45 p.m. - its getting darker. Reds are gone. in the photograph you see that the lines of the "waterfall" picture are getting unsteady. Flickering. Overall light intensity is under 15%.
7:49 p.m. - last picture. The greens and blues will be the last ones to disappear. These are the "colours of the shadows". And yes, when it gets dark, I think I often still can see and distinguish the green colours from leafs when all the other colours have faded to grey. But now I know its not only my eyes that can detect them in the dark, but the spectrograph as well.
I also managed to find a fluorescent lamp for calibration. So you can compare the images and the wavelengths.