Weather Wednesday: What is black ice and how does it form?

Weather Wednesday

LANSING, Mich. (WLNS) – You hear this a lot in the fall and winter: “Watch out for black ice.”

For this week’s Weather Wednesday meteorologist Kendall Wilson explains how it forms and what to keep in mind while driving.

Imagine this. You’re taking your morning commute on what appears to be a normal winter day, driving a what appears to be a clear road when all of a sudden your car starts slipping and sliding. Soon you realize that you have just hit a patch of black ice.

Even though we are all aware of the possibility of black ice on the roads, we are here for you now to explain what black ice actually is and how it gets on the roads in the first place.

But before we get into the actual nit and grit behind the formation of black ice, we need to make sure that we are on the same page about what black ice actually is.

Black ice isn’t actually black, but clear.

You might be asking yourself, well, ‘isn’t all ice clear?” Not necessarily think about the ice cubes you get in drinks at various restaurants.

Some are clear where others are more opaque and white. The color of the ice all comes down to the structure. With black ice, there aren’t any bubbles allowing for transparency.

For how black ice actually forms, we first need a source of moisture or water, but not just any type of water or precipitation, it has to fall gently as it hits the ground.

It’s a small distinction that actually has a major impact on the visibility of ice. If the rain were heavy, it would allow bubbles to become trapped in the ice structure, meaning it would be visible to the naked eye. Also, we would need calm winds outside for the same reason.

Now, those are the ingredients for black ice, but it turns out there are actually a wide variety of scenarios that allow it to form.

It’s most common to see black ice after a light sprinkle in the area, as well as when snow and slush melts during the day and refreezes at night. But it can also form when fog or dew freezes as temperatures drop. Interestingly enough, although less common, it can also form from the condensation that gathers on your vehicles.

And as you are traveling this holiday season and through the fall and winter, remember that ice will form on bridges or overpasses before it forms roadways and sidewalks.

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