What are those white lines left by airplanes in the sky, and where do they come from?

Ultimately, these white lines are the discreet signature of passing aircraft, a natural phenomenon linked to the cold and humidity of high altitudes. They are neither mysterious nor worrisome: they simply remind us that, even above our heads, nature and technology interact harmoniously.

A great reason to keep looking up and dreaming a little more often… and to admire these  condensation trails  like an aerial spectacle, or like a  natural painting in motion .