Dear Tom,
How does "black ice" differ from regular ice, if it does?
-Dr. Leon J. Hoffman, Chicago
Dear Dr. Hoffman,
Black ice is just regular ice that forms in a thin layer on roads or sidewalks. It is almost
invisible because it takes on the color of the underlying pavement, which on asphalt
surfaces is black. It poses a major problem for unsuspecting motorists and pedestrians
who have been traveling on dry pavement and suddenly encounter loss of traction, failing
to realize they are on an icy surface. Black ice forms when moisture refreezes after a
snowmelt, from freezing drizzle, windblown snow or frozen condensation. The term
originally was used to describe a thin layer of ice on a pond or lake, but in recent years its
usage to describe a road hazard has become predominate.
