What is glare

The measure of brightness or intensity of light is lumens. Indoors, for example, most artificial light has an intensity of 400 to 600 lumens. If it is sunny outdoors, the brightness will fluctuate over a wide range, the brightness of the shade is 1000 lumens, and the brightness of the place with a large cement floor such as the highway is 6000 lumens. Below 3,500 lumens, our eyes feel comfortable. When the brightness of direct or reflected light reaches 4,000 lumens, the human eye begins to have difficulty receiving light. When we try to look hard at these very bright areas, we only see a white flash, which is glare. To reduce the discomfort caused by the amount of light entering our eyes, we start squinting. Once the brightness reaches 10,000 lumens, your eyes begin to filter out the light completely because the light they receive is too strong. Exposure to such intense light for too long can cause damage, leading to temporary or even permanent blindness. On a clear day, the light reflected by a large area of snow can be as bright as 12,000 lumens, and if we look directly at it without any protection, we will be "snow blind".
Visible light is the light that the human eye can detect. The visible light we see from the sun appears colorless, which is what we often call white light. In fact, it is made up of a mixture of different frequencies of colored light. Light mixed with all colored light in the visible spectrum is colorless, that is, white. (For more information, see Principles of Light).
There are two basic ways we see colors. One way is that an object itself emits light of a certain frequency, such as neon lights, which show colors; Another way is that the object absorbs all other frequencies of light and reflects only a certain frequency of light, or reflects multiple frequencies of light, and these light waves mix and are perceived as one color of light, for example, painted objects show color in this way. For example, one way to see yellow light is for an object to emit light at a yellow frequency directly; Another way is to absorb light in the blue part of the spectrum and reflect light in the red and green parts, which are mixed and perceived as yellow by the human eye.