Ok, "light does not travel well through air"....
Lets dispense with that pile first, if that were the case (it isn't, light does not travel well through clouds, but does not have much of an issue with clear air....) Then during the day the side of the sky where the sun is would be light, and the side of the sky away from the sun would be dark. Unless light is making some incredible bends for no reason...
Lensing effects, as in that stupid canal experiment, and being able to see long distances over water under certain conditions, are an exception to the rule caused by light traveling from areas of lower density to areas of higher densities, I would recommend you look up Snell's law, it is the same principle, however these effects can only bend light a few degrees over very, very long distances. Not cause light to work its way around in a loop.