When you say radar as a method of vehicle tracking legally, do you mean GPS? If so, I am pretty sure this is legal. However, you may want to check with your state because each state has their own ruling.
Radar
radar is one main way to track aeroplanes :D
radar
That is radar, which is short for radio direction and ranging.
The answer, both technologically and legally, is "No". Most modern in-car Police radar systems can work while the vehicle is moving.
The answer is "yes." Traffic radar monitors both the speed of the vehicle in which is it mounted and the speed of "target" vehicles coming toward or moving away from it. On the radar display, the officer sees two speeds: "patrol" (the speed of his vehicle) and "target" (the speed of the vehicle the radar is tracking). the target speed measurement is equally accurate, whether the patrol vehicle is moving or not.
radar
tracking radar
Clouds are formed from water vapour - which is virtually invisible to radar.
Radar
radar
Doppler radar