Originally Posted By: KD0AXS
Originally Posted By: eljefino
When you get snowbanks you get freeze/thaw cycles and a little water on the shoulder that could sneak back into travel lanes. This causes "black ice" for the morning commute.
That's not black ice. Black ice is caused when temps are well below zero and the water vapor in exhaust from vehicles freezes on the pavement. This type of ice is essentially invisible, it appears to be dry pavement. That's where the term "black ice" came from. When it's that cold, salt is useless. At those temps, it's too cols for the salt to melt the ice.
https://en.wikipedia.org/wiki/Black_ice
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."[3] Because it represents only a thin accumulation, black ice is highly transparent and thus difficult to see as compared with snow, frozen slush, or thicker ice layers. In addition, it often is interleaved with wet pavement, which is nearly identical in appearance.
So... why not both?
Regardless, snowmelt and refreeze is not white in color nor all that visible and the desire for salt to keep this problem under control on clear days between storms exists.
Originally Posted By: eljefino
When you get snowbanks you get freeze/thaw cycles and a little water on the shoulder that could sneak back into travel lanes. This causes "black ice" for the morning commute.
That's not black ice. Black ice is caused when temps are well below zero and the water vapor in exhaust from vehicles freezes on the pavement. This type of ice is essentially invisible, it appears to be dry pavement. That's where the term "black ice" came from. When it's that cold, salt is useless. At those temps, it's too cols for the salt to melt the ice.
https://en.wikipedia.org/wiki/Black_ice
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."[3] Because it represents only a thin accumulation, black ice is highly transparent and thus difficult to see as compared with snow, frozen slush, or thicker ice layers. In addition, it often is interleaved with wet pavement, which is nearly identical in appearance.
So... why not both?
Regardless, snowmelt and refreeze is not white in color nor all that visible and the desire for salt to keep this problem under control on clear days between storms exists.