A few days ago i witnessed a real life example of atmospheric tunnelling. Due to warm air over cold waters, the skyline of La Rochelle was faintly visible over 50 km away, despite it being normally below the horizon.
I’ve seen this kind of optical phenomenon precisely twice. The air is usually close to the dewpoint and fog either has just dissipated, or is close to forming. Normally you don’t see anything of La Rochelle, even on very clear days. The only thing that is visible is light during night long exposures ... Read even more
