[Donald Tulip]

Donald Tulip asked the Naked Scientists:
   
Is there a way to tell the difference, visually, between sunrise and sunset?

What do you think?

[LeeE]

The scattering of light is slightly more pronounced in the evening than in the morning due to the air being warmer, and the increased level of dust due to daytime activity.  The result is that the sky will be tend to be 'redder' in the evening than in the morning, all other things being equal.