Driving in fog? Here's what to know about how fog forms, how to stay safe
With rain and possible fog moving into the Phoenix metro area Monday, drivers may wonder if it is safe to be on the roads.
Fog can be dangerous if it reduces visibility, such as when fog mixed with smoke from fires in New Orleans last year and caused a 158-car pileup. However, fog does not always have such drastic consequences or effects.
For those who may be driving in the Valley while fog creeps in, here's what we know about the different types of fog and how to drive in foggy conditions.
Does Arizona see a lot of fog?
According to Current Results, a weather and science website, Phoenix sees an annual average of seven days that have fog.
How is fog formed?
According to The National Weather Service, six types of fog can form in different ways.
Hail Fog - Falls after a heavy hailstorm when cold balls of ice fall into warm and moist air near the surface, creating patchy and shallow fog
Radiation Fog - Forms at night when skies are clear and winds are calm when heat absorbed by the earth's surface during the day is radiated into space. As the earth's surface cools, if there is a deep enough layer of moist air near the ground, humidity will reach 100% and fog will form.
Valley Fog - A type of radiation fog, it forms when air along the upper slopes of mountains begins to cool after sunset. The air becomes dense and heavy and starts to drain down into the valley floors. As air on the valley floor continues to cool, the air becomes saturated, and the fog forms.
Advection fog - The result of condensation caused by the horizontal movement of warm and moist air over a cold surface. It looks like radiation fog but is distinguished by its horizontal motion along the ground.
Freezing fog - Occurs when water droplets remain liquid until they come into contact with a cold surface and can freeze. Freezing fog can coat anything in ice it comes in contact with.
Evaporation or mixing fog - Forms when water vapor is added to the air by evaporation and moist air mixes with a dry area, creating steam fog and frontal fog. Steam fog forms when cold air moves over warm water. Frontal fog forms when warm raindrops evaporate into a cooler, dryer layer of air near the ground.
Should I drive in fog?
According to the Arizona Department of Transportation, if the fog is too dense and reduces visibility, those on the road should delay their travel.
How do I drive in fog?
ADOT and the National Weather Service say those who drive during foggy conditions should:
Keep a safe distance between you and the vehicle ahead
Don’t tailgate
Use headlights and fog lights
Slow down to provide more control if something unexpected occurs
Minimize distractions
Allow extra time to reach your destination
Make your vehicle visible to others, both ahead of you and behind you, by using your low-beam headlights
Never use your high-beam lights. Using high-beam lights causes glare, making it more difficult for you to see what’s ahead of you on the road
Stay in the proper lane by following the lines on the road with your eyes
In extremely dense fog where visibility is near zero, the best course of action is to first turn on your hazard lights, then pull into a safe location and stop
If there is no parking lot or driveway to pull into, pull your vehicle off to the side of the road as far as possible. Once you come to a stop, turn off all lights except your hazard flashing lights, set the emergency brake, and take your foot off the brake pedal to be sure the tail lights are not illuminated so that other drivers don't mistakenly run into you.
This article originally appeared on Arizona Republic: Driving in fog? Here's what to know about how fog forms, how to stay safe
