The wake is basically up to the wingtip vorticies, and if the plane is leaving a contrail the contrail gets entrained in the vortices, so the size of the contrail should give an indication of the size of the wake.
There will also (I imagine) be ripples in the air, that propagate sideways like the V shape of a boat, but that's a different type of thing
How long does the wake last....if the contrail persist in line shape for a long time does the wake also persist or dissipate?
The vortices spread out? The spreading wake of boat provides the biggest bump as opposed the wash behind the prop.