How many meters of fog visibility in meteorology refers to what to look at and how to distinguish between light fog and heavy fog.

People with normal vision can distinguish the maximum distance of a certain size black target from the sky background near the horizon. Atmosphere (two disciplines)]

Visibility less than 10 km is called light fog; Visibility less than 1 km is called fog.

In practical work, the visibility less than 500 meters is called dense fog, and the visibility less than 200 meters is called strong fog. Yellow and orange warnings are issued respectively, and the strong fog with visibility less than 50 meters is issued with red warning.

In the past and now, observers mainly observe with the naked eye. At present, there are fully automatic visibility monitoring stations to effectively monitor the real-time situation of road weather, and data is fed back to the meteorological observatory every minute. The monitoring station is a forward scattering visibility meter, which can automatically observe the visibility affected by bad weather such as fog, gale and rainstorm, with the measuring range of 10- 10000 meters, and the observation data is transmitted through GPRS.