How can I deal with patch see through behavior?

Hello, I have a spherical patch object, on which I want to display data values. It looks like the image below when I plot it:

The face alpha is set to 0,5. When looking at the sphere, you can see the colours of both sides of the sphere.

how can I make the wierd spots dissapear, so I get a smooth color on the surface of the sphere.

Note: I want to keep the face alpha around 0.5, this is important for visualisation purposes.

Thanks!

[Walter Roberson]

Are you using lighting or shading ?

[Theo]

I'm using lighting