'It happened so fast': Black ice turns roads into invisible skating rinks

With the arrival of winter comes a seasonal hazard that's slippery, invisible and deadly – black ice.

Black ice, which is actually transparent, is the term for the thin coating of ice that can form on an otherwise clear road, turning it from steady surface to skating rink.

"That's why it's so dangerous," said Officer Carlos Perez, of California's Highway Patrol. "It's undetectable to the human eye. Many people don’t realize they’re driving on black ice until they’re spinning."

"It's very smooth and glossy and you can't really see it," he said.

As any driver who's hit a patch can tell you, it's dangerous in the extreme.

'It happened so fast'

Jack Whalen was driving on Interstate 81 in upstate New York when he hit a stretch of black ice many years ago. “It was very cold and had been snowing a little but the road looked pretty clear,” he said.

“I realized we were on a curve and so just barely touched my foot to the brake pedal to slow a bit and Wham! We instantly went into a crazy spin, turning completely around and more on the highway – we finally came to rest straddling both lanes.”

As soon as he’d recovered his wits, he drove onto the shoulder where he spent more than a few minutes getting his breath back before continuing on.

“By the grace of God it was late at night and with bad weather, traffic was light and there was no one close behind us,” the retired sociologist said.

The sensation of suddenly shifting from tires that have traction to tires that have none is what's so terrifying, said Karen Hunt Ellis, who vividly remembers a decades-old incident where she, then a new driver, hit a stretch of invisible ice while driving down from the Sierra Nevada.

"My whole family was in the car and I could have killed every last one of them," she said.

"We were approaching the crest of a hill and everything was fine. As we went over and were about to start descending, the wheels let loose of the road. It happened so fast. One moment all was fine and the next we were sliding sideways at the oddest angle," she said.

She overcorrected because the wheels weren't responding the way she expected them to.

"So I turned away from the skid again but by then we were off and flying. I remember turning the steering wheel a couple of times as I tried to straighten out, but eventually I just drifted onto the median."

The experience left her shaken but grateful that they were unharmed – and having learned a lesson she's never forgotten.

What is black ice?

Black ice isn't actually black, it's transparent. That's what makes it so dangerous. It's the thin coating of ice that can form on seemingly bare pavement when temperatures hover around freezing.

Black ice is different from a white or grey layer of ice that can form when roadways have been plowed or driven on, packing the snow or hail so that it freezes into a slippery layer. Often somewhat lumpy, that kind of ice something drivers can see, giving them a visual cue that they need to slow down.

As the California Highway Patrol warned after one of the first big winter freezes of 2024: "Here’s a little reminder from your CHP Truckee since we’ve been getting several spin-outs this morning… SLOW DOWN!! Remember: drive like you’re tiptoeing past a sleeping bear and your ex just texted ‘we need to talk.’ ?? Slow down and drive safely!"

When does black ice form?

There are multiple conditions that can cause black ice to form on a roadway, say experts.

One of the most dangerous times is when roadways are plowed following a snow.

"The road looks clear. But then the temperature drops, most commonly at night or in the early morning, the freezing point goes down and the residual moisture on the roadway freezes," said Perez.

Another danger point is when there's a snow storm followed by clear skies.

"You get a lot of snow and then two or three days of sun and the snow melts. But there's a lot of moisture on the road and when the temperature falls below freezing it becomes ice," said Ahmed Abohassan, a traffic safety data analyst in Edmonton, Alberta in Canada whose thesis was on winter driving dangers and pavement friction.

Bridges are especially dangerous because air currents above and below make them cooler than roads on solid ground, creating more favorable conditions for black ice. Underpasses are also dangerous because shade can mean they freeze when other pavement is clear.

This is why many highways sport "Bridge ices before road" or "Bridge freezes before road" signs just before drivers come to a bridge or overpass, so they have time to slow down.

How can black ice form when there's no snow or rain?

It's counterintuitive, but black ice can form on roadways even when it hasn't rained or snowed.

This happens when the air temperature is very close to the dew point, the temperature at which air can no longer hold moisture, said Abohassan.

"When the air temperature drops below the dew point, any excess moisture condenses to a liquid on the roadway and ice can form," he said.

Frost and fog can also cause the ice to form.

What should you do if you hit black ice?

If you hit black ice, try not to panic, said Perez of the California Highway Patrol. He works in the Truckee, California area where cars are coming up into the Sierra Nevada on their way to Lake Tahoe and the area's many ski resorts. His social media posts on the dangers – and need for caution – have gained him a serious following.

The best thing to do is try to avoid skidding:

• Slow down: The absolute best way to protect yourself is to slow down when conditions are hazardous.

• Turn off cruise control: If you're in a situation where black ice might be present, the first thing to do is turn off cruise control, said Perez. "Never, ever, ever drive with cruise control when you’re going through icy or snowy conditions," he said.

• Pay attention to your car's warnings: Nowadays most new cars have a temperature warning that alerts you to freezing conditions. They tell you you're driving in a dangerous environment and that you should be more cautious, said Perez. The icon typically comes on when temperatures are around 31 or 32 degrees and often looks like a snowflake icon, though that varies according to the make and model of the vehicle. "It's telling you conditions are dangerous," said Perez. "Pay attention."

• Be especially alert at night: While an icy coating can form on a roadway at any time of day or night given the right temperature and moisture conditions, nighttime is the most dangerous for drivers because the ice is even more invisible than in the daylight.

If you do hit a patch of black ice and start to skid:

• Stop accelerating: "The first thing is to take your foot off the gas – pressing the gas can cause you to spin," Perez said.

• Lightly tap the brakes: Once you start slowing down, start slightly tapping the brakes, he said. Don't slam them on, which can cause the vehicle to slide even more.

• 'Turn into the skid': Common driving advice often says "turn into the skid," which simply means to turn the steering wheel in the direction the front of the vehicle is going, so the wheels are aligned with the vehicle's motion. But the advice varies a bit depending on the type of car you have.

  • For rear-wheel, all-wheel drive and 4x4 vehicles: After you have taken your foot off the accelerator, steer into the skid to help correct, said Perez. That means turning your steering wheel – gently! – in the direction the front of the car is going, to help you regain traction on the roadway.

  • For front-wheel drive vehicles: After you have taken your foot off the accelerator, steer in the direction you want the vehicle to go to help correct the skid.

• Don't panic: Keep both hands on the steering wheel and your eyes on the road. "Some people close their eyes because they've panicked," Perez said.

Slow down to stay safe when black ice could lurk

Give yourself plenty of distance from other vehicles when traveling in cold weather. On bare pavement when traveling 50 miles per hour, a car requires 118 feet to come to a complete stop. On packed snow, it's 450 feet. But on ice it's a whopping 655 feet.

"That's a loooong way," said Abohassan. "People underestimate it."

The best course of action when driving when black ice is a possibility is to slow down and be cautious. People tend to speed up once they get out of snow, freezing rain or fog because they can see clearly again. But they may not be seeing the danger.

"People look at the posted speed limit and think 'If I'm driving the posted speed, I'm safe.' That's not true," said Abohassan. "Traffic safety people will tell you to drive for the conditions. The posted speed limit is the maximum, not the minimum."

This article originally appeared on USA TODAY: What is black ice? How to stay safe from winter's invisible danger.