Aerial Perspective (Atmospheric Perspective): Term coined by Leonardo da Vinci for the method he used to create an illusion of depth in painting by imitating the way the atmosphere makes distant objects appear less distinct and more bluish than they would be if they were closer.
Although other artists had already begun to create some of these effects in their work, Leonardo da Vinci was the first to make careful measurements and suggest rules for applying them realistically in painting.
From: The Boston Museum of Science
The shadows of objects get bluer and lighter as they recede into the composition, while objects presented in the light lose yellow as they recede.
Adrian Gottlieb
GottliebStudios.com/Classical_Glossary