What wind speeds can do
Meteorologists still use the wind-force scale developed by Sir Francis Beaufort of the British Royal Navy in the early 1800s.
Less than 1 mph
Completely calm. Smoke rises vertically.
Smoke drifts, but weather vanes don't budge.
Leaves rustle, weather vanes turn and you can feel a breeze.
Light flags extend, but the breeze remains gentle.
Hang onto loose paper. Small tree branches move.
Small, leafy trees begin to sway.
Larger tree branches move. Umbrellas can turn inside out.
Whole trees move; walkers feel wind resistance.
Trees sway more, and twigs break; walking is tough.
Minor damage to buildings begins to occur.
Trees break or fall, and structural damage is considerable.
A rare wind this strong causes widespread damage.
SOURCE: NOAA. GRAPHIC: Laura Stanton and Bonnie Berkowitz - The Washington Post. Published Aug. 26, 2011.