Why does varying air density change the angle of light refraction?

[cragar]

Ok i get that hotter air is less dense , but when light goes from hot air to colder air we are dealing with the same atoms it is just that the photon will have less collisions , why would the angle of re-emission change for the photon just because it is having less or more collisions in the medium. As the photon gets absorbed and re-emitted , why would this cause refraction just because the atoms are close together and then far apart how does this change the angle that the photon gets re-emitted out of the atom .

 

[JDługosz]

When light passes through transparent air, it does not collide and bounce around. Classically, you can view that light slows down because the matter (seen as a bunch of fuzzy electron clouds) changes the way the electric and magnetic fields act.

Denser matter, all else being equal, increases the effect.

The spreading electric field has to fight against the background of negative charge, so it responds slower. That's an analogy, not to be taken too literally.

--John

 

[cragar]

that is an interesting answer .