What is relevant here is height above the ground, as the various forces that he describes are a facet of the ground effect (or lack of ground effect). e.g. You

What is relevant here is height above the ground, as the various forces that he describes are a facet of the ground effect (or lack of ground effect). e.g. You would find the top of the CN tower an endlessly windy, environmentally unfriendly place. Yet standing on the street in Madrid you are just as high and suffer none of the same effects.