Is the Speed of Light Affected by Atmospheric Conditions?

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Do photons travel at the speed of light (c) inside the Earth's atomphere? Or is friction a factor of their velocity.

Ty
 
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Photons are constantly being emitted and reabsorbed by interactions with the molecules in the Earth's atmosphere. Do you want the speed of the photons themselves (which is always c, but because of quantum effects is problematical to measure), or the average speed at which energy is transferred through the Earth's atmosphere (which is easy to measure, and directly related to effects such as diffraction, but is lower than 'c')?
 
Ty, I would like to know the average speed at which energy is transferred through the Earth's atmosphere thnx
 
At standard temperature and pressure, the index of refraction of air is 1.00029 for light in the middle of the visible spectrum. That means that its speed is c/1.00029. Higher in the atmosphere the index of refraction will be even closer to 1. Friction is not a word associated with the transmission of light, as far as I know.
 

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