Grigg-Putnam Index

The Griggs-Putnam Index is one of several empirical methods of estimating the prevailing wind speed at a site by observing the growth patterns of trees. Strong winds will deform trees and shrubs so that they indicate an integrated record of the local wind speeds during their lives

I – Brushing occurs when small branches bends downwards.

II-III-IV – Flagging occurs when large branches bends downwards, and branches which are upwind are shorter than branches which are downwind.
V-VI – Throwing occurs when the actual trunk of the tree curves downwind.

VII – Carpeting occurs when the trunk grows along the ground.