Why do City lights flicker when seen from a distance?
In: Physics
Two reasons that I can think of. One is particulates in the air, like dust, that changes how much light gets through. As dust moves around, it blocks some light, which you’ll see as flickering. The other reason is light refraction due to humidity and temperature variations.
The index of refraction of air changes when the air temperature changes.
This causes air bubbles of different temperature to act like lenses.
But since air isn’t solid these bubbes wobble around. Causing the flickering.
This happens only at long distances because the difference in index of refraction of different temperature air is very small. So the air will change the light direction only very slightly and the light needs to travel a very long distance for this to be visible.
And if the light is large it won’t flicker because even if some part of is is refracted so that it won’t reach your eye some other part of the light is still visible. You will see its edges wobble around.
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