This morning we had freezing fog around Kentuckiana. It starts happening this time of year, when the skies clear, winds are calm, and the temperatures drop - then you get fog, especially in the river valleys. When you get all of those fog ingredients together with sub-freezing temperatures you get freezing fog.
But, freezing fog is a little misleading. It can cause black ice on bridges/overpasses, but freezing fog is actually made of tiny liquid drops suspended in the air, that then freeze on contact with a below-freezing surface.
Meteorologist Jeff Haby does a great job explaining interesting weather in simple ways,
"As a general rule, liquid cloud or precipitation drops between freezing and -10 C (14 F) will remain liquid. When the temperature drops to below -40 C, all liquid droplets will solidify. Droplets that are liquid and are below freezing are referred to as supercooled droplets."
When temperatures hit -40 C or below, then you get ice fog.
Haby says, "Ice fog is a fog composed of tiny ice crystals. In the ice fog situation the temperature is becoming too cold for only supercooled water to occur. Ice fog will only be witnessed in cold Arctic / Polar air."
You can see that river fog this morning below in the picture. That's a fuzzy look at the Clark Memorial Bridge.
Head to theweatherprediction for more fun weather facts.