Drifting Dust or Sand
(Section 3.2.2.2.1)Definition: Drifting dust or sand: Dust or sand raised by the wind to small heights above the ground. The visibility is not sensibly diminished at eye level (eye level is defined as 1.80 m above the ground).
Very low obstacles are veiled or hidden by the moving dust or sand. The motion of the particles of dust or sand is more or less parallel to the ground.