Fall is well known in Minnesota and the Upper Midwest for its beautiful colors, many comfortable days and crisp nights. Some years the colors seem so vibrant and plentiful, yet once in awhile, fall will seem to be frequently gray with lingering overcasts, continually damp, and cold that seems to go right through one’s body. But two things fall is sure to bring are nights with temperatures at or below 32 degrees, and the potential for freezing rain. Along with that mixture, one can find black ice!
Quite simply, “black ice” is a thin sheet of ice that can form on a sidewalk, road, ramp, taxiway or runway when there is sufficient moisture and the temperature is at or below freezing.
By the way, black ice is not black at all. It is actually transparent and often appears as a shiny, black spot or area on the road, taxiway or runway. It can be the size of a small puddle, or it can cover very large surface areas. In varying light conditions, it can be essentially invisible on sidewalks.
Black ice can also be caused by the exhaust of vehicles standing still with engines idling. It can be hidden by fallen leaves, blowing dust, or even trash. Black ice can also form very quickly on bridge decks, or sections of roads, runways or taxiways that may pass over a culvert.
When the fall season arrives with all its splendor, or even with all its rainy and dreary days, keep in mind that as the temperature drops closer to freezing, the chances of black ice forming increase. Use caution when taxiing, driving, or even just walking. Continue moving forward slowly, but do not apply the vehicle or aircraft brakes when on black ice. Watch carefully for other spots of black ice and be prepared to carefully handle a situation if one occurs.