Grazing Light: Directional light at an acute angle, which emphasized texture. The sources of grazing light must be close to the surface.

At sunset, in the middle of a desert, when the sun gets really low at the horizon, the light is almost perfectly horizontal and the rough textures naturally present in a desert landscape are enhanced to perfection. Also all the clouds in the sky get illuminated in a way that gives them more volume and highlights their natural shapes.