What is the sign of fog?

The fog warning signal is divided into three levels, which are represented by yellow, orange and red respectively.

(1) foggy yellow warning signal

Standard: Fog with visibility less than 500m may appear within 12 hours, or fog with visibility less than 500m and greater than or equal to 200m has already appeared, and the defense will continue. Introduction: 1. The relevant departments and units shall prepare for fog prevention in accordance with their duties; 2 airports, highways, ferry terminals and other units to strengthen traffic management to ensure safety; 3. Drivers should pay attention to the change of fog and drive carefully; 4. Pay attention to safety in outdoor activities. (2) Fog orange warning signal

Standard: Fog with visibility less than 200m may appear within 6 hours, or fog with visibility less than 200m and greater than or equal to 50m has appeared and will continue. Guide to defense: 1. The relevant departments and units shall, in accordance with their duties, do a good job in fog prevention; 2. Airports, expressways, ferry terminals and other units should strengthen dispatching and command; 3. Drivers must strictly control the speed of cars and ships; 4. Reduce outdoor activities. ? (3) Fog red warning signal standard: Fog with visibility less than 50m may appear within 2 hours, or fog with visibility less than 50m has appeared and will continue.

When the relative humidity reaches 100%, the water vapor in the air will condense into fine water droplets suspended in the air, which will reduce the visibility on the ground. This weather phenomenon is called fog.

Fog is more common in spring from February to April. When the visibility in the atmosphere is lower than 1 km due to the condensation of suspended water vapor, meteorology calls this weather phenomenon fog. Conditions for fog formation: cooling, humidifying and increasing water vapor content. The types of fog are radiation fog, advection fog, mixed fog, evaporation fog and smoke.