What is the light or heavy snow reported in the weather forecast based on?

Snow is a solid deposit of condensed water vapor in the sky. The condensation of water refers to the process of water vapor directly changing into ice crystals without water. According to the intensity of precipitation, snowfall is divided into four grades: light snow, medium snow, heavy snow and blizzard. Light snow: refers to snow when the horizontal visual distance is equal to or greater than 1000 m, the ground snow depth is less than 3 cm, the 24-hour precipitation level, and the snowfall is between 0. 1 ~ 2.4 mm. Snow: refers to snow when the horizontal visual distance is between 500 ~ 1000 m, and the ground snow depth is 3 ~ 5 cm. 24-hour snowfall is 2.5 ~ 4 .. Heavy snow: refers to the poor visibility when it snows, the horizontal visual distance is less than 500m, the depth of snow on the ground is equal to or greater than 5cm, and the 24-hour snowfall reaches 5.0 ~ 9.9mm. If there is snowfall but no snow is formed, it is generally called "sporadic light snow". When the snowfall reaches 10.0 ~ 19.9 mm in 24 hours, it is a blizzard, 20.0 ~ 29.9 mm is a blizzard, and more than 30.0 mm is a blizzard.