FTP, what is this light produced when charged particles move through a medium faster than the speed of light in that medium?
It causes the weak bluish white glow in polls of water that shield some nuclear reactors.  It is created by highly energetic charged particles that displace electrons in the medium through which they travel, and the subsequent electromagnetic wave in the wake of these particles is similar to the bow wave of a fast boat.  FTP, what is this light produced when charged particles move through a medium faster than the speed of light in that medium?
It causes the weak bluish white glow in polls of water that shield some nuclear reactors.  
Cherenkov or Cerenkov radiation