What do you already know about how wind interacts with trees?
- Trees are like big levers. They are attached at the bottom and free
swaying at the top.
- The crown of the tree is like a sail. Wind acting on the crown creates
a 'drag force.' This drag force is multiplied by the lever arm to produce
a turning moment around the point of attachment.
- Because trees are flexible, the crown is displaced. The mass of the
crown is multiplied by the length of displacement to produce an additional
- As trees grow taller, the length of the lever arm increases. This
means that the turning moment will increase even if the crown stays
the same size.