Sunsets tend to be warmer than sunrises, with gold and orange tones proliferating due to the particles in the warmer air reflecting sunlight to create this color shift. In the morning, at sunrise, the air isn’t so warm and humid and tends to be clearer, producing more pink and blue cool tones, typically, than at the end of the day.
When the sun is visible above the horizon, whether after sunrise or before sunset, it will produce stronger, warmer, low-angle directional light than it will when it’s below the horizon. When hidden there, the sun is indirectly illuminating your scene by bouncing off the roof of the sky. If that’s the right look for your subject, use this to determine whether you want to shoot at sunrise or sunset. A west-facing building, for instance, will need to be shot before sunset to capitalize on this warm, direct light on the façade and prevent you from shooting directly into a strong light source. An east-facing façade, however, will need to be shot at sunrise. (Remember, too, that shooting the sunrise requires setting up in the dark. So plan ahead for this added challenge.)
Once the sun dips below the horizon at sunset (or before it crests the horizon at sunrise) that is called “twilight.” At this time of day, the light will be softer and non-directional, which provides more options for which direction you point your camera. If you’d like the bright glow in the sky to illuminate the face of your subject, it will need to be at your back—meaning you’ll need to be facing west when shooting in morning twilight or facing east when shooting post-sunset twilight. But if you want that glow visible in the scene, you’ll need to reverse your position. It all depends on the nature of the subject and what you want to see in the frame. If you’re photographing a building with a lot of glass and steel (i.e. reflective surfaces) consider putting that glow at your back. If, however, the subject is a brick façade, a portrait or a landscape, including the beauty of the twilight glow in the background of the scene might require shooting at the other end of the day.
Not all parts of the magic hour are the same, but by considering the differences in the quality of the light and its direction at sunrise and sunset, with the sun visible in the sky or during twilight, you can actively choose the ideal time of day to create the precise look you’re going for.