The golden hour
February 12, 2016 7:18 AM   Subscribe

Can we tell the difference between sunrise and sunset by sight alone?

I feel like if I am shown a photo of a sunrise or sunset, I can tell which part of the day it is (without any other obvious clues present). Is there something inherent in a sunrise/sunset that makes it easy to distinguish one from the other or am I potentially basing my judgement on something else that I'm not realizing?
posted by triggerfinger to Science & Nature (9 answers total) 10 users marked this as a favorite
optically, all i can think of is that the atmosphere is likely warmer during sunset than sunrise, which might make things appear slightly different (eg more shimmering). but i imagine it's a tiny effect and only noticeable comparing the two (because a sunset in winter would have cooler atmosphere than a sunrise in summer, for example).

otherwise, things seem like they would be pretty symmetric. the green flash, for example, should be visible in either case.
posted by andrewcooke at 7:30 AM on February 12, 2016

Best answer: The answer, from some atmospheric physicists.
posted by pipeski at 7:42 AM on February 12, 2016 [15 favorites]

The colors are different.

Sunrise is more yellow, sunset is more red.

I base this solely on personal observation.
posted by Ms Vegetable at 7:42 AM on February 12, 2016

Best answer: Previously, including some discussion of video
posted by Nonsteroidal Anti-Inflammatory Drug at 8:21 AM on February 12, 2016

I can tell which part of the day it is (without any other obvious clues present).

You may be grabbing onto clues even in a photo which don't seem obvious but are:

*Mist rising from the ground is usually sunrise as the dew begins to evaporate
*Boats heading *out* to the sea usually means sunrise, whereas boats heading in means sunset.

I'me sure there are more things...
posted by vacapinta at 8:27 AM on February 12, 2016

If you've always lived, say, on the East coast of the US, then you may subconsciously associate the sun over the water with sunrise, or some more subtle clues dependent on things like weather formations etc.

Another possibility is that the photographers make different choices for sunrise and sen set pictures because they have different associations, or maybe because the photographer's eyes aren't adapted to light early in the morning.

I can't think of any physical reason why they'd look different, so I guess the difference is in your perception somewhere.
posted by Ned G at 10:28 AM on February 12, 2016

If you're comparing images of known locations, you can figure out whether the camera that took the photo is facing east or west.

Depending on where you are, there may be perceptual differences. The color of sunlight at different times of day is radically different in all of the places I've lived, but in general, the sunrise is usually whiter/bluer than the sunset, which is yellower/pinker. Still images of a sunset low in the sky always seem redder than a sunrise, to me.
posted by blnkfrnk at 12:29 PM on February 12, 2016

the sunrise is usually whiter/bluer than the sunset, which is yellower/pinker

This may correspond to the level of atmospheric pollution, which tends to be a lot lower in the early morning than in the evening.
posted by pipeski at 2:26 PM on February 12, 2016

I don't really have a good answer, but relevant experience. I commute east in the morning and west in the evening. At sunrise, the sun is literally, blindingly glaring. I don't have the same problem at sunset. I have no idea why.
posted by kamikazegopher at 7:21 AM on February 13, 2016

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