How should a controller assess the movement of wingtip vortices from a heavy aircraft near the ground?

1. They generally descend and spread outward, while ambient wind transports them; a light crosswind can keep one vortex near a runway or move the other toward a parallel runway, so published wake minima and cautions remain essential.
2. Vortices rise rapidly into the upper stratosphere within 5 seconds.
3. Vortices remain completely motionless regardless of wind.
4. Vortices are instantly destroyed by light winds.