What happens to vortices that contact the ground in a no-wind situation?

When vortices come into contact with the ground in a no-wind situation, they tend to move laterally outward. This phenomenon occurs because the interaction between the vortex and the ground creates a change in pressure and flow patterns. As the vortex descends and touches the surface, the airflow is disrupted, leading to a spreading effect where the energy of the vortex is redistributed laterally. This lateral movement is significant in understanding wake turbulence, especially around larger aircraft, which can pose hazards to smaller aircraft during takeoff and landing.

In contrast, the other options suggest different behaviors of the vortices that do not occur under these specific conditions. Dissipation would imply an immediate breakdown of the vortex, which is not the case as they have enough energy to interact with the ground. Moving upward contradicts the fact that the vortices are already at ground level, and intensifying would imply an increase in strength, which does not happen in a stable, no-wind environment where the energy is instead dispersed laterally. Understanding these characteristics is crucial for pilots and air traffic control in managing safety during flight operations.