Driving in fog is more dangerous than you think. Each year, the National Weather Service estimates there are 511 deaths caused by fog each year. That’s 25% higher than the rate of winter weather-related casualties. Knowing how to deal with foggy driving and when to avoid it could keep you from being involved in one of the over 31,000 fog-related crashes this year.
What is Fog?
When hot, moist air cools, water falls out of suspension. This water gathers in droplets, forming a cloud. Meteorologists define fog as any cloud near the earth’s surface that reduces visibility below one kilometer, or about 0.6 miles.
The most common type is radiation fog. During the night, cold ground cools the air above it. Add some wind, and enough warm air is chilled to form water droplets.
Advection fog occurs when warm air moves over a cold surface, like snow or water. This type of fog is common around this part of Wisconsin thanks to Lake Michigan. Since it takes a lot of energy to heat water, the lake stays colder than the surrounding air through the spring and summer. Add some wind, and you have the perfect conditions for fog formation.
Why is fog mostly an early morning phenomenon? Once the sun rises, increasing temperatures create air currents that mix dry and moist air, absorbing the water droplets. This gradually shrinks the cloud.
What Do Fog Warnings Mean?
The National Weather Surface issues two types of fog warnings. A Dense Fog Advisory is issued when visibility is at or below a quarter mile. At 70 MPH, it takes about 13 seconds to travel ¼ mile.
A Freezing Fog Advisory is issued when fog develops during times when ground temperatures are at or below freezing. The water droplets can turn into ice on contact with surfaces ranging from overpasses or windshields. Even light freezing fog makes driving dangerous.
How Can I Stay Safe Driving in Fog?
Check your speedometer: Limited vision reduces the time we have to react to obstacles, but the lack of reference points tricks our brains into thinking we’re going slower than we actually are. Go by your speedometer, not your vision, to keep speed in check.
Use the right lights: Fog hangs low, but doesn’t quite reach the ground. Turning on your high beams sends light directly into the cloud, reflecting off water droplets and hindering your vision. If your car has fog lights, use them. They’re mounted low to provide light across the surface of the road below the cloud layer. Low beams may not do much to help you see, but they need to be on so other drivers can see you.
Focus on the road, not other vehicles: The glow of a set of tail lights gives you a reference far ahead of what you can see normally. However, focusing on another vehicle keeps you from scanning the road, so you may miss something before it’s too late. Instead, keep track of the road markings to make sure you’re in your lane.
Turn safety systems on, but don’t depend on them: Collision avoidance systems can sometimes sense obstacles that you can’t see, giving you more time to react. However, they’re also less reliable in bad weather. If you’re driving in freezing fog, ice buildup can block sensors, keeping them from reading traffic.
Foggy skies mean wet roads: The moisture in the fog ends up on the road, making driving surfaces wet even when it hasn’t rained. If it’s freezing, the ground can ice over, particularly on bridges and overpasses.
When You Have an Accident, Come See Us
Even the most skilled, best prepared driver can have an accident. If you need collision repair, visit Merton Auto Body. We’ve served Lisbon, North Lake, Pewaukee and the rest of Lake Country for over 70 years. We’re accredited by I-CAR and ASE, so you can rely on us to fix your car right, whether it’s brand new or an antique. We’re also the first choice for many major insurance companies thanks to our reputation for quality work and short job times. Need an estimate? Our on-staff appraisers will work with your insurance company.