Things have gotten chillier up in the Northern Hemisphere. With chilly seasons come their challenges. For example, if there's one term guaranteed to make car-owners lose their cool, it's "black ice." The National Weather Service defines this as "patchy ice on roadways or other transportation surfaces that cannot easily be seen."
To the human eye, it's all but invisible. Black ice isn't really black; it's transparent. The stuff only looks black when it's covering a layer of jet-black pavement. Accidents happen once drivers, blind to the danger, steer their cars over the ice and lose traction.
Other kinds of ice are easier to see. You've no doubt noticed that homemade ice cubes usually look cloudy and opaque in the middle, like whitish blocks of cotton candy. That stands in contrast to the frightening clarity of black ice. How come black ice is see-through, but the cubes in your typical ice trays aren't?