Animating from day to night

Is there a way to control using a script or a combination of scripts to simulate day to night transition? I am looking for not just a texture animation but also the color of lights.etc

yes there is.

see here and here (look especially at the directional light)

Besides there being solutions for this issue in the asset store - this and that - you can of course do it manually via script or animation, although it’s not easy to get realistic behavior a-la CryEngine 3.

Your algorithm should be able to generate (or at the very least alternate between) skyboxes or clouds (the asset store solutions both use layered alpha-cut planes to make ‘volumetric’ clouds), change the color and angle of the light according to the time of day and the longitude/latitude coordinates etc.