I would like to ask ... please share where you live (or lived) to have knowledge about different ice conditions.
Not all ice is created the same.
Black ice is unique in temps below 0F (-18C): Black ice happens when motor vehicles are stopped and idling, the exhaust warm snow & ice on the road surface. When the vehicles moves on, the melt freezes quickly. Road salt is not effective at these temps and black ice is common at stop lights and on road after rush hour congestion. It is near impossible to see black ice (and the reason for the name).
Refreeze ice is commonly called black ice, but it's different. Refreeze happens on milder, sunny days; and when day temps are above freezing and nights are blow freezing. Refreeze ice isn't typically an issue on road surfaces because road salt and traffic won't let ice form. But refreeze is an issue on the shoulder of roads, bike trails, and bridge decks.
Why does it matter ... ice is ice, right? From the saddle of a bike it matters because you want to know when and where to look for ice that will be hard to see. For example, this morning it's -20F (-29C) and I'm riding to work, when riding in the traffic lane coming up to a stop light there's a good chance of ice being on the road surface. Approach the red lights with extra stopping distance and be aware of people in cars not doing the same. OTOH I'm riding to work when it's 25F (-4C), the day before was sunny and temps above freezing, I need to look for ice on shoulders and on bike only trails as well as shady areas.
Refreeze example, I was not riding winter tires, and I turned in the shady part of the road and took a fall (and a reminder to use the winter bike)
Next weeks wedge issue: different terms for snow conditions
