Glare is difficulty seeing in the presence of bright light such as direct or reflected sunlight or artificial light such as car headlamps at night. Because of this, some cars include mirrors with automatic anti-glare functions.
Glare can reduce visibility by:
reduction of brightness of the rest of the scene by constriction of the pupils
reduction in contrast of the rest of the scene by scattering of the bright light within the eye.
reduction in contrast by scattering light in particles in the air, as when the headlights of a car lights up the fog close to the vehicle, impeding vision at larger distance.
reduction in contrast between print and paper by reflection of the light source in the printed matter (veiling glare).
reduction in contrast by reflection of bright areas on the surface of a transparent medium as glass, plastic or water; for example when the sky is reflected in a lake, so that the bottom below or objects in the water cannot be seen (veiling glare).
Sunglasses are often worn to reduce glare; polarized sunglasses are designed to reduce glare caused by light reflected from non-metallic surfaces such as water, glossy printed matter or painted surfaces.
