Must be a lot of turbulence downwind of them. If the disturbance stretches for 20 times the height.. Dont put the race course too close to them. Say goodbye to any interesting birds as well.
I wonder about the bird problem with these wind farms. Where I live you can't drive anywhere for a few minutes without seeing the remains of some bird on the road. When I think of the scale of the road system and imagine how many dead birds there must be lying on roads, I really can't see how the numbers that fly into wind generators can be significant.
If the numbers were comparable the maintenance people would have to bulldoze the carcases out of the way just to get to the base of the tower!
If it really is a serious problem then maybe we should be ripping up the roads to save the birds!