Calm, smoke rises vertically
Smoke drift indicates wind direction, still wind vanes
Wind felt on face, leaves rustle, vanes begin to move
Leaves and small twigs constantly moving, light flags extended

Dust, leaves, and loose paper lifted, small tree branches move
Small trees in leaf begin to sway
Larger tree branches moving, whistling in wires
Whole trees moving, resistance felt walking against wind

Twigs breaking off trees, generally impedes progress
Slight structural damage occurs, slate blows off roofs
Seldom experienced on land, trees broken or uprooted,
"Considerable structural damage"

Devastation Occurs