Originally Posted by
Sixty Fiver
Black ice forms at colder temperatures via condensation of car exhaust... 19F is actually a little warm for that to happen.
Ok according to
this article, it is also formed at warmer temps:
The American Meteorological Society Glossary of Meteorology includes the definition of black ice as "a thin sheet of ice, relatively dark in appearance, [that] may form when light rain or drizzle falls on a road surface that is at a temperature below 0 °C.
However, it goes on to say:
At low temperatures (below –18 °C), black ice can form on roadways when the moisture from automobile exhaust condenses on the road surface.[4] Such conditions caused multiple accidents in Minnesota when the temperatures dipped below –18 °C for a prolonged period of time in mid-December 2008.[5] Salt's ineffectiveness at melting ice at these temperatures compounds the problem.[6]
19F is between these zones, so may explain why I feel so cavalier about riding then.