Painting the transition from day to night — the twilight and golden hour periods — is one of my favorite subjects because the light does things during these transitions that don't occur at any other time.

Golden hour: the sun is near the horizon and the light path through atmosphere is long, filtering out short wavelengths. The result is strongly warm orange-gold direct light with very long shadows. The shadow color is cool purple-blue (skylight from the remaining blue zenith).

Civil twilight: the sun is just below the horizon. There is no direct sun but the sky is still bright. The light is extremely soft and cool. Shadows have almost no directionality.

Nautical twilight: the sky is dark enough for stars to appear. The horizon has a gradient from orange at the very lowest horizon, through blue-green in the lower sky, to deep blue-purple at the zenith. The orange-to-blue gradient is one of the most beautiful color transitions in nature.

The practical painting lesson: during golden hour, the orange of the direct light and the blue of the sky create the most extreme warm-cool contrast of any natural lighting condition. This contrast makes golden hour paintings read as dramatic without requiring any other compositional intensification.