[skykooler]

This is one of the reasons ATC maintains a certain separation between landing aircraft. For larger airliners which produce more turbulence, this separation needs to be greater. As you can see from the video, wake turbulence migrates downwards over time, so after thirty seconds or so it's no longer an issue for other aircraft on the same glideslope.

[webreac]

The separation between a heavy flight and a small one is 120s. There are many studies to take into account wind (speed and direction) and to have finer table of spacing (often around 85s) taking into account both aircraft types. Near the runway, there is also a ground effect with reflection of the vortex.