Except for time and temperature signs or electronic billboards as otherwise regulated herein, all billboards must be stationary and may not contain any visible moving parts or alternating or moving messages, or have the appearance of having moving parts or messages. Under no circumstances may any type of billboard contain a message or display that appears to flash, ungulate, pulse, move or portray explosions, fireworks, flashes of light or blinking lights or otherwise appear to move forward or away from the viewer, expand or contract, bounce, rotate, sign, twist or make other comparable movements.