Why do city lights flicker from a distance?

Question

Why do city lights flicker from a distance?

Answer 1

atmosphere distortion

Answer 2

Consider the source of lights.  The low level lights come from houses.  The bright lights come from cars, which are moving, causes a "strobe" affect.  Street lamps and other bright lights, which are stationary, will have the lights distorted as the EM wave passes through prisms.  Hot and cold air acts as prisms.  Air is moving, therefore the moving prisms between you and the light source will make distant light flicker.