Courtesy vgm8383Its really cold where I live these days. It was 23 below zero Celsius (this is a science blog) this morning when I woke up. Bitter cold. An interesting phenomenon happens on roads when it gets this cold, a condition called black ice. It was in full effect this morning, with Twin City roads having over a dozen accidents and causing lengthy commute delays.
So, what is black ice (besides an AC/DC album)?
Black ice is a type of ice that is usually thin and forms without bubbles inside, making it harder to see. Because of its transparency, it usually takes on the color of whatever it is on, making it doubly hard to see and a hazard to drivers, bikers and walkers.
Black ice on roads is most common at night or in the early morning when temperatures are at their lowest, and before the sun has had a chance to warm the road surface. It can be mixed in with a wet road, and it can be hard to tell the difference between a road that is wet and a road that has black ice. Black ice can form more easily on bridges and overpasses as the very cold air can cool both the top and the bottom of the road at the same time, causing it to cool below freezing more quickly. Black ice can form from any source of moisture – light rain, meting and re-freezing snow or any other source of moisture on a road surface.
Here are some tips for driving on black ice. Drive safe my fellow Minnesotans – I’m going to be on the road with you this evening!