fog line

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
   • Along the coast Sequoia sempervirens does not grow above the altitude to which the moist sea air generally rises — the fog-line, as it is often called.1895, On the Various Stages of Development of Spermatobium, with Notes on Other Parasitic Sporozoa
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
   • The reference line is a straight line that runs the length of the accident site, such as a fog line on a straight road.2006, Truck Accident Litigation, volume 978, page 45