When the sun is rising you’re getting indirect, diffuse light which is slowly and steadily increasing, as the sun gets closer to the horizon – going from black to blue. It happens the exact opposite when the sun is setting. Direct light becomes indirect and diffuse, turning from blue to black.
They don’t actually look that different, just mirrored. But that’s enough to make it seem very different. If someone showed you a still picture of dawn twilight and dusk twilight without labels, you wouldn’t be able to tell which was which
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