What effect would a crosswind of 5 knots or less have on the wingtip vortices generated by a large aircraft that had just taken off?

A light crosswind of 5 knots or less would indeed influence the behavior of wingtip vortices generated by a large aircraft during takeoff. Specifically, the upwind vortex would tend to remain closer to the runway for a longer period compared to the downwind vortex because the crosswind causes a lateral dispersion of the vortices.

As the aircraft takes off, the wingtip vortices are formed due to the difference in pressure above and below the wings. In a light crosswind scenario, the upwind vortex is partially blown back towards the runway while the downwind vortex moves away from it, due to the wind direction. Thus, in these conditions, the upwind vortex remains in a position that is more likely to affect subsequent aircraft taking off or landing, as it does not drift away as quickly as the downwind vortex.

Understanding this dynamic is crucial for flight safety, particularly in busy operations where separation from vortices is necessary to prevent wake turbulence encounters.