Environmental impact of visibility

Visibility varies greatly in different environments.

Visibility can reach 70 ~ 100 km in the arctic or mountainous areas where the air is particularly clean. However, due to air pollution and humidity, visibility is usually reduced. Weather stations all over the country reported haze (dry) or fog (wet). Smoke can reduce visibility to zero, which is very dangerous for driving and sailing. It is also very dangerous to drive in desert areas with sandstorms and forest fires. The rainstorm in thunderstorm weather not only reduces visibility, but also makes the ground slippery and unable to brake urgently. Blizzard weather also belongs to the category of low visibility.

Smoke, fog and haze

Internationally, the visibility of smog is defined as less than 1km, the visibility of mist is 1 km ~ 2 km, and the visibility of haze is 2 km ~ 5 km. Smoke and mist are usually considered as important components of water droplets, and the particle size of haze and mist is relatively small, which indicates that some detectors such as thermal imager TI/LIR use far infrared with the wavelength of about 10um, because its particle size is smaller than the wavelength, it can better penetrate haze and some smoke. Therefore, infrared radiation has neither changed direction obviously nor been completely absorbed by particles.

Visibility is very low.

Visibility less than 100 meters is usually considered as zero. In this case, the road will be blocked and automatic warning lights and signs will be activated to remind drivers and friends. These warning signs are usually placed in places where visibility is often low, especially in places where major traffic accidents (such as car pileups) have occurred.