Gradual Darkening of Objects - Please Help!

Hello, thanks for looking at this…

I’m making an animation with sky, clouds, scenery etc. during the daytime, and I need it to turn to night on rollover of a particular button. I’m such a flash virgin though, I don’t know how to do this.

I’m guessing there’s a way of changing the colours/tints of the objects so I can keep the same place in the animation, but I’d also like to make changes happen in the animation like leaves falling, lightning, bats… is there a way of doing this in a new scene but keeping the clouds from the first scene so they don’t jump to a different point in the animation?

Thank you for reading, I really hope you can help.

Cheers!