Now that winter is behind us and spring is officially here, you could be forgiven for dropping your guard and being a bit less cautious on the roads. While driving conditions are significantly less hazardous than during the darker winter months, temperatures can still drop below freezing overnight, which presents the perfect conditions for the hidden danger popularly known as black ice.
What is black ice?
As the roads become snow free, people can be lulled into a false sense of security because when temperatures drop, a clear, thin coat of ice can develop on the pavement. The term black ice can be misleading because it is in fact a transparent sheet of ice that is only black because of the roadbase beneath it. The only clue you might have is that at night the shiny surface may reflect in the headlights.
What causes black ice?
Black ice occurs because of moisture on the road, either from snow and ice melt on or near the roadway or precipitation in the form of drizzle, rain or fog that lands on the road. As the temperature of the road surface drops below freezing, the thin sheet of water freezes, which creates the ice.
During the early spring months, this is particularly concerning because daytime temperatures warm above freezing and precipitation will and can fall in the form of rain, drizzle, or mist instead of the frozen variety. As the sun sets and the temperatures drop back to below freezing, conditions are perfect for black ice to form. Areas that are at greater risk are shaded areas on the sides of hills or areas lined with trees because these areas have not received the extended warmth of the sun during the day and drop back below freezing quickly, leaving more time for the ice to form.
Bridges and overpasses are also a big concern because these elevated areas have cold air that passes under them, causing their temperature to be lower than the surrounding roads.
How can I avoid black ice?
Realistically this hazard cannot be completely avoided, but here are some tips for what you can do:
Pay attention to the road
When driving in the evening or night hours be aware if the temperature is at the freezing point, there is a risk of black ice developing. Don’t be fooled by the false sense of security of the warm spring day that preceded the night. Watch for shiny patches on the road. Frequently the black ice forms in patches and not on the entire road surface.
Know what to do if you hit a patch of black ice
Do not try to overcorrect by steering out of the ice patch. Your vehicle will be sliding across a patch of ice and steering will not be effective. Your best bet is to hold tight to your steering wheel with your tires straight and when you cross the patch of ice to the dry pavement on the other side your tires will be straight on the road.
Learn how to apply your brakes
Like the previous comment on steering, your vehicle will be sliding on a patch of ice so use of brakes will not be effective until they reach dry pavement on the other side of the ice patch. When this happens you may get a jolt when the brakes do grab the surface that you didn’t anticipate.
The Bottom Line
Our best advice is to remain aware of black ice throughout the spring season when temperatures fluctuate above and below freezing. The ground has not yet thawed and still retains both heat and cold which magnifies on the precipitation on the surface. Slow down and use caution. Sand and salt can only be effective in keeping the ice off if it is not washed away by the water flowing across the surface. Once the temperatures remain above freezing throughout the entire day, this is the time when the risk for black ice decreases. Drive safely this spring.
About the Author
Nicole Stevens is an intern meteorologist at Iteris' Weather Operations Center in Grand Forks, ND.
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