In rain, fog headlights or heavy snow ordinary light beam reduces the efficiency of road lighting. The first reaction to the deterioration of visibility is the inclusion of high beam, but at the same time the driver understands that the situation has only gotten worse, it is happening because of the blinding effect. The explanation is simple, the main beam is not limited and does not cut off the top of the light beam. Driving beam reflected from the mist droplets or snowflakes, blinding the driver’s by reflected light.
With constant ambient light, amount of light entering the eye per unit time is proportional to the area of the pupil. The eye responds to ambient light reflex widening or narrowing the pupil, and the pupil reacts with unlit eyes, it is called a friendly response to light.
Fog light is specially designed for bad weather and initially provides its highly directional applications.
Fog headlights lights have a wide light distribution diagram in the horizontal and very narrow beam vertically. The main objective of the fog lights to shine like a fog, rain or snow thus without dazzling the driver’s by reflected light, as is the case with the main beam.
Requirements for fog lamps: the upper cut-off must be as sharp, scattering angle in the vertical plane – the smallest, about 5 degrees, and the highest in the horizontal plane, about 60 degrees, and the maximum light intensity should be close to the upper cut-off.