As a first approximation, sunrises and sunsets should look pretty much the same, as they are both visions of the sun through a long piece of atmosphere. Red light is scattered less than blue light, so the sun tends to look red, with the blue that's missing being the blue of the sky for someone else.
That being said, there are some effects which could make a difference. For example, at sunset, the air near you is likely warmer than at sunrise on average, and the cooler air of the morning could increase the odds of clouds or fog which would affect your view.
In addition, if there are effects which kick up dust or other particles during the day, this will contribute to the reddening of the sunset but not to the sunrise, so there will be a difference.
There could also be psychological effects, depending on how you feel in the morning or evening, or what emotions you associate with sunrises and sunsets.
For a sunrise you might still have a chance to see some of the remnants of a star-filled night sky, with your eyes relatively adapted to the dark, but this is likely a subtle effect and could easily be modified by what sorts of light you were looking at before you checked out the sunrise or sunset.
There are also clearly geographical features which are unique to the sunrise and sunset in any given place - the sun rises over the ocean on the East Coast, but not the West Coast.
I don't think one could easily tell from any single photograph whether it was of a sunrise or a sunset, but with some additional information one might be able to hazard a guess, or at least separate a stack of photographs of sunrises and sunsets taken in the same place with some degree of accuracy.
Dr. Knowledge is written by physicists Stephen Reucroft and John Swain, both of Northeastern University. E-mail questions to drknowledge @globe.com or write Dr. Knowledge, c/o The Boston Globe, PO Box 55819, Boston, MA 02205-5819.
