In calm conditions close to the ground, vortices will generally move laterally at what speed?

In calm conditions close to the ground, wake turbulence, or vortices generated by aircraft, typically moves laterally at a speed of 2 to 3 knots. This range reflects the natural dispersion and movement of the vortices as they interact with the surrounding air.

The lateral movement of vortices is crucial for air traffic control, as it helps determine how long the wake turbulence will persist in the vicinity of an airfield after an aircraft has taken off or landed. The influence of these vortices diminishes with distance from the aircraft that generated them, but knowing their movement speed aids in ensuring the safety of following aircraft during takeoff and approach phases.

In comparison, the other options suggest higher speeds for the movement of these vortices, which are not representative of their behavior in calm, near-ground conditions. Understanding the proper speed of these vortices is essential for effective air traffic management and maintaining safe separation between aircraft.