World of Tanks bug? Aiming on horizont in WoT!!!

I will shot where i aim, so why the target cursor aimed on horizont make those click fun turns? And nobody cannot aim properly where he will? I thing this is a wierd. When the enemy vehicle is on horizont and you shot on him, when he disapear from spot range and you will shot at him for blind shot, you cannot cause you shot at the clouds! :-)