What is it?
Wind is the movement of air from high pressure to low pressure. Differences in pressure create pressure gradients in the atmospere. The steeper the gradient, or closer the differences in pressure, the stronger the wind.
If the barometric pressure is the same over a large area there should be no wind, the nightmare of those generating electricity from wind. In the Columbia River Gorge in the Pacific Northwest the wind always blows, except when it doesn’t. There were fourteen straight days in 2009 when none of the wind turbines in the gorge turned.