Many of us feel ready for the cold season to end. Winter continues until the third week of March, though. Some nasty winter storms may still be ahead of us.
The worst type is the ice storm, also known as “freezing rain”. The typical scenario happens when a cold front has pushed all the 50’s temperatures out of Georgia and established a mass of dry, crispy, cold Canadian air. For a few nights, the mercury drops into the 20’s and below. Then, a storm from the Texas coast gains strength over a pocket of warmer ocean water. It gets dragged into the westerly (west to east) airflow over the U.S. mainland and drifts into Georgia. Rain from the coastal storm now hits the frozen ground surface, and a layer of ice forms. Roads, trees, rooftops and utility lines quickly accumulate a heavy white layer. It’s the kind of storm where you read “thousands of households without power” in the Times the next day, because the weight of the ice can make power lines collapse. Even if it doesn’t, ice-laden tree branches or entire trees can fall on the cables, knocking entire subdivisions off the grid.
The real killer, though, are the road surfaces. Driving on snow is quite possible. But driving on solid ice only works at pedestrian speed, with no upward or downward slope, and plenty of time budgeted for braking. Most communities have stopped using salt on iced roadways. It’s effective but harmful to plants and groundwater, as well as to the sheet metal of cars. Sand works by providing traction but doesn’t actually melt the ice like salt does.
When the ice storm has passed and temperatures are above freezing again, hazards still linger. “Black ice” is a patch of ice with very few air bubbles, which makes it transparent. One sees only what looks like a wet road surface. In reality, it’s extremely slippery. Even on a sunny, mild day following an ice storm, experienced drivers know to watch the landscape ahead. Air is a very poor conductor of heat. Driving from sunny, open ground into a wooded patch can put you into a very cold air pocket. With no sun hitting the road, ice can remain, sometimes invisible. Watch out for dense stands of trees on both sides of the road, especially with a sharp curve ahead.
Rudi Kiefer, Ph.D., is a professor at Brenau University, teaching physical and health sciences on Brenau’s Georgia campuses and in China. His column appears Sundays and at gainesvilletimes.com.