Warning signal of sandstorm weather and its significance

Sandstorm weather belongs to disastrous weather. When it is predicted that it may happen, the competent meteorological department will send an early warning signal to the whole society. Early warning is divided into three levels: yellow warning, orange warning and red warning. The three-level warning symbol and its meaning are as follows: the disaster color symbol means sandstorm yellow 12 hours, sandstorm weather may occur (visibility is less than 1000 meters), or sandstorm weather has appeared and may continue. Strong sandstorm weather may appear within 6 hours of orange (visibility less than 500 meters), or it has already appeared and may continue. There may be extremely strong sandstorm weather (visibility less than 50 meters) within 6 hours of red, or there has been extremely strong sandstorm weather, and it may continue.