A link to some research. If the computer models can be believed then there is an up to three mile downwind effect...
"A study from the University of Kansas School of Engineering sheds light on a potential safety hazard that could affect hundreds of airports across the country ... turbines can set up a circular vortex that can roll a plane ... By using advance computational aerodynamics modeling, the KU research team studied the effect of winds from 10-40 miles per hour. They found the higher the wind speed, the farther the turbulence reached – stretching as far as nearly three miles from a single turbine..."
https://www.wind-watch.org/news/2014...ar-wind-farms/
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