fogline

Noun

fog line (plural fog lines)

1. The boundary of a body of air, contacting the earth's surface, that has fallen below the dew point and usually contains fog.
2. A division in altitude above which fog appears.
   • Along the base of the Sierra, back of Pasadena, on eastward back of San Gabriel, past Cucamongo, with its noted vineyards, above Pomona and on beyond San Bernardino, growing warmer as it recedes eastward from the sea, is a belt of foothills above the fog line, facing out toward the noonday sun...1884 June, The Overland Monthly, page 596
3. A line painted on a road (usually bright white) that marks the edge of the legally drivable portion.
   • As the driver of the vehicle reached into the glove box to obtain the insurance information another westbound vehicle crossed the fog line traveling onto the north shoulder of the roadway.2003, Isaiah McKinnon, In the Line of Duty: A Tribute to Fallen Law Enforcement Officers from the State of Michigan