Photographers and Cinematographers sometimes use the term “magic hour” to refer to times of day when natural daylight takes on special qualities that beautify nearly any setting and imbue it with drama and grandeur. Unfortunately the phrase is used inconsistently to refer to times just before or just after sunup or sundown. I prefer the terms “golden hour” for those times when the sun is just above the horizon, and “blue hour” for the time of twilight, when the sun is below the horizon but the sky carries a hint of its glow. Of course, “hour” is also imprecise, as the duration of the times of magical light depends on season and latitude. The tropics may have warm weather all year round, but there the setting of the sun is abrupt. In St. Petersburg or in Patagonia, on the other hand, the sky can be numinously luminous all day long.
At the golden hour, the sun comes nearly sideways through the atmosphere, passing through significantly more air than when it comes from overhead. This softens and diffuses the light, and absorbs many of the short (blue) wavelengths, giving it a warm golden or reddish tone. The landscape is illuminated laterally, with raking shadows revealing the texture of surfaces and things.
Side lighting is particularly flattering to human subjects. In stage lighting, illumination from the sides is usual for dance, as it emphasizes the shapes of the body. The warm tone of late afternoon or early morning light has its own glamorizing effect, reducing harshness and making blemishes and wrinkles less visible. The softer light doesn’t make people squint as harsh midday light does, nor does it cast dark shadows under their eyebrows and noses.
When the light comes from behind through translucent things like leaves, grass, or hair, those objects glow with transmitted light, overpowering the ordinary reflected light by which we see opaque things.
When low in the sky, the sun casts shadows laterally, sometimes outlining the shapes of trees and people and things upright on walls, rather than beneath them on the ground or floor.
Direct lateral sunlight exposes textural contours in a reddish light, while the overhead blue light diffused through the sky provides a second, softer source of light. At a particular time these two light sources, red from the side and blue from overhead, may be almost perfectly balanced.
A golden glint and long shadows turn the plainest structures into glittering metallic facets.
Buildings are shadowed by other buildings, and the red glow of the setting or rising sun selectively ignites the gridlike structures.
Just as the sun drops below the horizon, the level of daylight comes into balance with the level of artificial lights. Buildings are illuminated both from without and from within.
At certain times, from certain angles of view, reflected light is more powerful than any direct light, outlining softly illuminated subjects against a sharp antipodal sheen.
Once the sun drops below the horizon, the sky retains a diffuse ultramarine glow for some time before darkness completely overtakes the celestial vault. Artificial lights are now dominant, but the twilight glow pervades the shadows. Now it is is the blue hour.
The remaining light in the sky gives every unlit thing a blue glow, while interiors and places with artificial lighting shine in warmer tones.
The sky is blue, sodium vapor streetlamps are reddish, incandescent bulbs yellowish, fluorescent lights greenish.
The photo below is taken while there was a twilight blue glow in the sky. Fifteen minutes later, and the women would have been silhouettes against the artificially lit background.
Wet streets reflect the sky, so the blue glow comes from below as well as above.
As night descends, the overarching dome of light that is the sky gives way to the many separate sources of light that rule the urban night – headlights, streetlights, working lights, signal lights, display lights.
When the level of the long wavelength street lighting matches the level of the short wavelength twilight sky, red runs through blue like rivulets of blood in icy water.
Through reflection, the golden light of incandescence penetrates the deep blue of the gloaming.
The last phase of twilight is an indigo glow that barely rises above black, a memory of light, a faint resonance, a lingering echo.