The actual reason for this phenomenon has to do with using the least amount of energy to get through both media. It is the same angle but displaced from the incoming light ray. In other words they are parallel. This assumes that the surfaces of the pane are also parallel. They are not parallel.
Light travels faster in thin air than thick air.
Thus, when sunlight passes through the different layers of the atmosphere, it is bent toward the thinner air and this bending is at such an angle as to reach our eyes after the actual sun is below the horizon. The total effect of this refraction is to increase the actual time of daylight as compared to having no atmosphere at all. A mirage is a displaced image cause by refraction. A ray of light from a star passes through shifting air currents and thus appears to be coming in from different directions. Refraction is the bending of light cause by a speed change when it passes through different media.