Atmospheric diffraction

Atmospheric diffraction is the bending of light caused by the air in the atmosphere. When light travels through the air, the air molecules scatter some of the light in different directions. This makes the light bend around obstacles like mountains, buildings, and other things between you and what you are looking at. Because of atmospheric diffraction, you can sometimes see distant objects on the horizon, even when they would be blocked by a mountain or building if you were close up to them.