<P> 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 ( 32 ° F ) . '' 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 . This makes driving , cycling or walking on affected surfaces extremely dangerous . Deicing with salt ( sodium chloride ) is effective down to temperatures of about − 18 ° C ( 0 ° F ) . Other compounds such as magnesium chloride or calcium chloride have been used for very cold temperatures since the freezing - point depression of their solutions is lower . </P>
<P> 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 ( 32 ° F ) . '' 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 . This makes driving , cycling or walking on affected surfaces extremely dangerous . Deicing with salt ( sodium chloride ) is effective down to temperatures of about − 18 ° C ( 0 ° F ) . Other compounds such as magnesium chloride or calcium chloride have been used for very cold temperatures since the freezing - point depression of their solutions is lower . </P>
at what temperature does water freeze on the roads
at what temperature does water freeze on the roads
a temperature below 0 ° C ( 32 ° F )
a temperature below 0 ° C ( 32 ° F )