Task: Class Definition Understanding (ontology: Earth_Environment/SWEET)

Which of the following definitions best describes 'upslope fog'?

A. Occurrence of fog or haze in which considerable amounts of acidic material have been taken up from the gas phase, resulting in pH values less than approximately 3 in the liquid phase.
B. An advection fog produced as a monsoon circulation that transports warm moist air over a colder surface.
C. A type of fog, composed of suspended particles of ice, partly ice crystals 20 to 100 m in diameter, but chiefly, especially when dense, droxtals 12?20 m in diameter. It occurs at very low temperatures, and usually in clear, calm weather in high latitudes. The sun is usually visible and may cause halo phenomena. the concept is rare at temperatures warmer than -30?C, and increases in frequency with decreasing temperature until it is almost always present at air temperatures of -45?C in the vicinity of a source of water vapor. Such sources are the open water of fast-flowing streams or of the sea, herds of animals, volcanoes, and especially products of combustion for heating or propulsion. At temperatures warmer than -30?C, these sources can cause steam fog of liquid water droplets, which may turn into the concept when cooled (see frost smoke). See ice-crystal haze, arctic mist.
D. A type of fog formed when air flows upward over rising terrain and is, consequently, adiabatically cooled to or below its dewpoint.

Answer: A type of fog formed when air flows upward over rising terrain and is, consequently, adiabatically cooled to or below its dewpoint.