What is the visibility in heavy fog or extremely dense fog conditions?
3 Answers
Visibility in heavy fog or extremely dense fog conditions is determined by distance. The specific details are as follows: 1. Yellow fog warning signal. Fog with visibility less than 500 meters may occur within 12 hours, or fog with visibility less than 500 meters but greater than or equal to 200 meters has already appeared and will persist. 2. Orange fog warning signal. Fog with visibility less than 200 meters may occur within 6 hours, or fog with visibility less than 200 meters but greater than or equal to 50 meters has already appeared and will persist. 3. Red fog warning signal. Fog with visibility less than 50 meters may occur within 2 hours, or fog with visibility less than 50 meters has already appeared and will persist.
I've been driving for over 20 years and have encountered many heavy fog conditions. In regular heavy fog, visibility is typically below 500 meters, and in some areas it can drop to around 300 meters. Severe fog is even more extreme, with visibility generally not exceeding 50 meters, and in extreme cases, it can drop to 10 meters where you can barely see anything. I remember once encountering thick fog on the highway—I had to squint my eyes and could only faintly see the flickering taillights of the car ahead. In such conditions, turning on fog lights is a must, and you have to keep your speed below 40 km/h, or else rear-end collisions become far too likely. New drivers especially need to be cautious—accident rates spike in foggy weather. Maintaining a safe following distance is crucial, and don't push yourself to keep driving if it's unsafe. Safety comes first.
I've always been fascinated by weather changes and have studied visibility standards in foggy conditions quite a bit. Heavy fog generally refers to visibility less than 1000 meters, but in reality, 200 to 500 meters is considered decent during thick fog. In extreme fog conditions, visibility can plummet to under 50 meters, making it feel like a bucket of ink has been splashed in front of your eyes. This weather significantly impacts driving, as light barely penetrates, requiring halving your speed for safety. I've also observed that fog density correlates with humidity – higher humidity means denser fog and a sharp drop in visibility. Turning on your lights and driving slowly is the most reliable approach, keeping a safe distance from other vehicles to avoid sudden incidents.
