APPENDIX A (continued)
Vegetation. Tall vegetation may substantially reduce wind speed at
ground level. Trees are very effective at absorbing wind energy rather than
deflecting it as do solid obstructions such as terrain and buildings. Two
types may be categorized: the surrounding forest and the isolated windbreak.
Within a forest, the velocity is minimum near the center of mass of the
foliage in the crown (approximately 0.75 times the height); in the absence of
underbrush there is a velocity increase among the tree stems.
The shape of the wind profile in the forest is contingent on the
type of the trees in the forest, their spacing and openings in the crown, and
the distance from the edge of the stand from which ground level wind can