Why do lights that are far away (particularly city lights) always look like they are flickering?

Question

When I look at city lights from a distance, no matter how still and unobstructed my line of sight is the distant lights always appear to be pulsing or flickering. Why is this? Is there a scientific explaination?

Answer 1

cuz th' wnds blwin th' treez

Answer 2

The process is exactly the same as the one that you see when you look along a very hot tarmac road and everything in the distance seems to shimmer. The temperature change from the warmer ground to the cooler atmosphere above changes the refractive index of the air which causes it to bend the light passing through it at different rates which in turn makes the object you see seem to move position. In the case of distant lights they seem to flicker.

Answer 3

It happens because the medium through which you are viewing the lights, the air, does not have a perfect, never changing, always constant, refractive index. Warm and cool air currents alter the refractive index in an unpredictable, constantly shifting pattern leading to the visual detection of "flickering" lights in the distance.

Answer 4

I think it's just atmospheric fluctuations between the light source and your perspective. Light tends to bend around humidity because it travels at a different wavelength through water, which makes up part of our atmosphere.

Answer 5

They flicker because of the atmospheric dust that is present in its path. According to rayleigh scattering, the dust present in the path of light will absorb the photons and reradiate it or disperse it. Hence they seem to flicker.