Hi coilbook,
I made some tests and honestly do not understand about this.
Medium radius is in meters, so 10000 are 10km; this means a sphere of 10km radius with center in active camera.
I tried with medium raius 1000 in a 10km scene and 0,001 density , it seems to work better than your, but there's just something I can not figure out..
I will investigate this to get more answers.
Regards
Paride