Answer:
Aerial perspective.
Explanation:
Aerial perspective is a painting technique where, especially through the use of color, an impression of depth can be brought into the painting. It is based on outdoor observations, which are used by painters to achieve the desired effect.
A painter can apply the aerial perspective in a painting in which a landscape is also depicted, whereby the background is depicted faintly with a gray-blue color in the dark areas. The human brain processes these images in such a way that an illusion of depth is created. If we observe slightly more distant areas through a dark tube, the blue coloring is much more noticeable, because it is automatically compensated for in the brain.
