What To Know About Fog And How To Stay Safe

Fog, especially when dense, can pose significant risks to drivers. It contributes to numerous accidents annually and can disrupt air travel by affecting visibility during takeoff and landing.

The National Weather Service (NWS) issues advisories when fog conditions become hazardous, underscoring the need for caution and preparation.

Types of Fog Advisories

1. Dense Fog Advisory: Issued when widespread dense fog reduces visibility to one-quarter of a mile or less. These conditions make travel challenging, requiring extra caution or avoidance when possible.
2. Freezing Fog Advisory: Issued when fog forms at or below freezing temperatures. The tiny liquid droplets in the fog freeze instantly on surfaces, making roads, vehicles, and other surfaces hazardous. Visibility is typically reduced to one mile or less.

Fog Safety Tips for Drivers

When driving in foggy conditions, follow these tips to ensure safety:

1. Slow Down: Allow extra time to reach your destination.
2. Use Low-Beam Headlights: Low beams improve visibility and ensure taillights are illuminated. Use fog lights if available.
3. Avoid High-Beam Lights: High beams cause glare, reducing your ability to see ahead.
4. Maintain Distance: Leave extra space between vehicles to account for sudden stops or traffic changes.
5. Follow Road Markings: Use road lines as a guide to stay in your lane.
6. Pull Over if Visibility is Zero:
7. Turn on hazard lights and pull into a safe location, such as a parking lot.
8. If no safe location is available, pull as far off the road as possible, turn off all lights except hazards, set the emergency brake, and release the brake pedal to prevent tail lights from being visible.

Fog Over Water: Sea Fog and Lake Fog

Fog that forms over water is commonly known as sea fog or lake fog. This type of fog occurs when warm, moist air flows over cooler water, common along the U.S. Pacific coastline, the Great Lakes, and other bodies of water.

1. Advection Fog: A type of sea fog that moves over land, creating hazards for motorists. It forms as moist air moves over cold ground, often persisting for days.
2. Radiation Fog Over Water: Fog forming over land can drift over water, posing risks for mariners.

The NWS issues Dense Fog Advisories for water visibility reduced to one mile or less.

Super Fog: A Dangerous Combination

Super fog forms when smoke from damp, smoldering organic material mixes with cooler, saturated air, reducing visibility to less than 10 feet.

1. Dangerous Conditions: Often found in low-lying areas like creek beds or drainage ditches. Super fog can lead to multi-vehicle pileups on highways.

Freezing Fog and Black Ice

Freezing fog occurs when supercooled droplets freeze on exposed surfaces, creating dangerous conditions:

1. Hazards: Surfaces like roads, vehicles, stairs, and sidewalks become icy.
2. Black Ice: Invisible to the eye, black ice is especially dangerous for drivers. Reduce speed and exercise caution.