Why do the tops of tall trees blow madly, but the bottom part of those same trees blow only slightly?
This doesn't always happen, but there are several reasons. First, the bottom part of a tree is typically thicker and more resistant to movement by the wind. Second, trees deflect wind. That's why they're often used to build 'wind breaks'. That deflection of wind breaks up the flow of wind, reducing speed, especially where there are several trees. The speed at the base may be as little as 25% of the speed at the top of the tree. For example, if winds are blowing at 40 mph near the top of the trees, the speed at the bottom may be as little as 10 mph.