It just looks wet on the road. Maybe a little shine. Until you take a step, drive away or brake and suddenly lose all grip. Black ice. But what exactly is that? And why do things so often go wrong with black ice?
Sleet is not ordinary slippery conditions, nor is snow that stays put. Meteorologically speaking, it is supercooled liquid water. That sounds contradictory, but water can remain liquid at subzero temperatures as long as it is moving.
Only when such a raindrop hits an object, such as the road, a tree or a sidewalk, does it freeze immediately. “That happens in a fraction of a second and produces a rock-hard, transparent ice layer,” explains Hans Nienhuis, weatherman at RTV Drenthe.
To get icy conditions, the atmosphere has to be built up just right. High in the clouds, precipitation is formed as snow. The snow falls through a warmer layer of air and melts into rain along the way.
