This seems like a naive question that I ought to know the answer to, but autumn is upon us and it seems like a good time to ask. The sun sets much earlier in autumn than in the height of summer, and it follows a higher or lower angle (shortening dusk) to the horizon, resulting in a change in the duration of dusk. But ultimately at any given minute of the day, it is simply a matter of geometry wrt the height of the sun above the horizon. Let's say that today's 5:30 sun is at 20 degrees high in the sky - same as as the summer's of, say, 8:30. So why does everything look so different now? I'm coming home at 5:30 today and the sun is glaring so much I can barely drive, its angle so low the shadows are dramatically long. Yet, last time I headed west in the summer at 8:30 it didn't seem nearly so stark. What else is making this so obviously uniquely an autumnal sunset distinct from a summer sunset?