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Sunrise and Sunset - Is there a difference?

  1. Jan 1, 2006 #1
    Short version:
    Is there any physical reason why a sunset should look different than a sunrise? The only differences between the two situations that I can think of is that the atmosphere should be cooler during a sunrise than a sunset. There's also the accumulated smog consideration if you're near a city, i.e. there will be very little smog at sunrise vs quite a bit at sunset.

    Long version:
    I was just looking at a nice coastline picture and trying to figure out whether it was a sunset on an easterly facing coast or sunrise on a westernly facing coast when it occured to me that the two situations should be roughly symmetric and so you shouldn't be able to tell the difference. I commented on this to a friend of mine, intending to get a chuckle out of sharing the experience, when he said that you can tell the difference by the colors in the sky.

    Now my friend isn't a physicist (or a meteorologist, for that matter), but he does do a lot of backpacking and has seen his fair share of sunrises and sunsets so there's a good chance he knows what he's talking about. I haven't been able to convince myself that there would be any real difference between the two though.
  2. jcsd
  3. Jan 1, 2006 #2
    Yes, I think it is the difference in temperature.
  4. Jan 1, 2006 #3
    I think it can also depend on where you are located on earth. Here in California we see mostly "blue" sun rises and "red" sunsets, but at the same time we can see the sun go directly below the ocean when it sets but not when it rises. If I compare our sunsets here in California to this picture of a sunrise in Japan (picture: http://www.jarl.or.jp/Japanese/2_Joho/2-6_stations/8j1rl/first-sunrise.jpg, they look pretty similar (to me at least).
  5. Jan 2, 2006 #4


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    Temperature of the atmosphere/ground is certainly part of it, but also the amount of dust in the air. With more human activity in a region, there is more particulate matter near the ground at sunset than at sunrise.

    Blue light is scattered much more than red light.
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