Black ice

From Glossary of Meteorology

black ice

  1. Thin, new ice on freshwater or saltwater, appearing dark in color because of its transparency, which is a result of its columnar grain structure.

    On lakes, black ice is commonly overlain by white ice formed from refrozen snow or slush.

  2. A mariner's term for a dreaded form of icing sometimes sufficiently heavy to capsize a small ship.

  3. A popular alternative for glaze. A thin sheet of ice, relatively dark in appearance, may form when light rain or drizzle falls on a road surface that is at a temperature below 0°C. It may also be formed when supercooled fog droplets are intercepted by buildings, fences, and vegetation.