What Is Black Ice?
One of the most dangerous driving conditions in winter climates is known as “black ice.” The condition is actually a thin glazing of clear ice that develops on highways – often after snow or ice on the road melts during the day and refreezes at night. The reference to black ice has to do with the appearance of this layer of ice on black, asphalt roads. Driving experts say the danger from black ice is that it is very difficult to detect, particularly at night.
How black ice forms. There are two main ways that black ice forms during the winter. Bridges and overpasses are particularly susceptible to the formation of this thin layer of ice because wintry winds often have access to both the bottom and top of the bridge’s surface, lowering the temperature on the bridge several degrees below the surface temperature. What is left from previous rains on the roadway can then freeze in spots. The second common way that black ice forms is a day or more after a winter precipitation event. The highways have been cleared of ice and snow and the daytime temperatures are now exceeding freezing. That leaves moisture on the road that can refreeze overnight when temperatures drop below freezing.
Danger posed by black ice. The greatest danger is that black ice is virtually undetectable. A motorist may slowly build up speeds on a trip after not encountering any snow or ice for a period of time. A patch of black ice on a bridge or overpass is enough to cause a vehicle to lose contact with the roadway and potentially cause an accident. A study of black ice conditions concluded that stopping on black ice can take nine times longer than normal.
How to handle black ice. Having snow tires or chains can help, but not that much, according to experts. When driving in wintry conditions that make black ice possible, it’s imperative to increase the distance between yourself and other vehicles and to be on high alert behind the wheel at all times. The worst thing to do if you find yourself losing control of your vehicle on black ice is to slam on the brakes, according to driving experts. That will actually cause you to lose more control and to perhaps begin spinning. Instead, steer gently into the direction of the spin and accelerate slightly once you’ve begun to regain traction.