Sunset/sunrise animation.

How can I do this in Unity. I mean the changes of color of the sky on the horizon and maybe the color of the clouds. And conserinig the clouds, there is blended skybox shader, but is it possible to use movie texture of clouds on a hemishere(skydome) for example? Can I use animations from terragen or ones made in 3d apps using some atmospheric plugins? I'm trying to find the right direction for research on the subject, so that my sunsets look nice.-).

maybe this can help. this is a shader that change the color of sky and sun by changing location and time of day.