Viewing ball help

In the image above you can see a small snowy baseplate and a sphere on top. I am trying to create an effect where you can only see whats on the baseplate if it is in the sphere like a snowglobe. The problem I run into is that I cannot make the parts partially transparent which would allow me to simply detect which parts are colliding with the sphere and make them transparent. If you could think of a way to create this same effect I would gladly appreciate the help. (I am not trying to make a snowglobe that was just an example)

Please don’t post twice on the same topic.

Can’t you just make a union with All parts inside of the sphere?