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CINDY DAY: Black ice - a slippery slope

Ice... lots of plain old ice.  Kaitlyn Alyson Gallant says the roads were rinks across P.E.I. Jan. 21.

We all have a few pet peeves and one of mine, oddly enough, is weather related.  It rears its ugly head a few times each winter:  black ice.  

I don’t have a problem with the ice itself, but I do get a little wound up about how and when the term is used.  

One day last week, my morning radio alarm came on just as the traffic reporter was reading his road report.  That’s when my heart skipped a few beats; my annual battle with the use of the term “black ice” was back!  

Black ice is common in the dead of winter, when the atmosphere has warmed up after a cold spell that leaves the temperature of the ground and roadway well below the freezing point.  Black ice,  also known as “glare ice” or “clear ice,” typically refers to a thin coating of glazed ice on a surface – usually the road.  Now “black ice” is not black at all, but it is transparent – allowing the black asphalt roadway to be seen through it.  The very thin layer of ice contains relatively little entrapped air in the form of bubbles; it’s those air bubbles that give ice its whitish colour.

Water that freezes or snow than melts and forms puddles that freeze are good examples of ice – just not black ice. 

We often create our own black ice.  On a very cold morning, when the road is bare and the night was clear, you’ll find icy spots at intersections as the rush hour gets going.  Moisture from the exhaust of idling cars freezes on the cold roads and forms black ice.  Bridges are dangerous, too.  Moisture rising off a body of water on a very cold day can leave a thin layer of black ice. 

The term black ice is often used to describe any type of ice that forms on roadways, even when standing water on roads turns to ice as the temperature falls below freezing.  But sometimes ice is just plain old ice. 


Cindy Day is the chief meteorologist for SaltWire Network.


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