Is it Dusk or Dawn?

Okay, this question has bugged me for while.

If someone were to show you two pictures, one taken just after dawn and one just before dusk (ie with the sun at the same distance from the horizon), is there any way to tell which is which?

This assumes that the location is completely unknown, ie no indication of East and West.


Depends what else was in the pictures, but it sounds like you’re talking about nothing more than the sun as an orange disc and the horizon as a silhouette, in which case it would be hard.

However, since we view a sunset through air that has been warmed during the day, I think I’d be right in saying that the sun would look less distorted at sunrise than it would at sunset, but even this is going to be highly variable.

If there was some identifiable flora in the picture foreground, it might be possible to work it out from which flowers were open etc…

After a full day being warmed by Mr. Sun and thoroughly mixed by the accompanying winds, the atmosphere at sunset is a miasma of dust and smog. After a relatively calm night with fewer winds, the particulates will largely have settled out, yielding a much cleaner-looking atmosphere by sunrise.

You know that huge, bulbous, often slightly aspherical sun you sometimes see sitting low on the horizon? The kind that’s so filtered and dimmed by the roiled, hazy atmosphere that you can look right at it? That’s a dusk sun.

You know that seemingly much smaller but searingly bright ball slightly above the horizon that leaves you blinking reverse-image spots? The kind that seems so crystal clear in the instant before you’re temporarily blinded that you’d swear you could see a solar flare or two? That’s a dawn sun.

[ul]:smiley: [sup]If it is overcast there is no difference.[/sup][/ul]