WIND SPEED APPROXIMATION |
| MPH |
WIND EFFECT |
| 0-1 |
Smoke rises vertically. |
| 2-3 |
Direction of wind shown by smoke drift, but not by wind vanes. |
| 4-7 |
Wind felt on face; leaves rustle; ordinary wind vane moved by wind. |
| 8-12 |
Leaves and twigs in constant motion; wind extends a light flag. |
| 13-18 |
Raises dust, loose paper; small branches are moved. |
| 19-24 |
Small trees in leaf begin to sway; crested wavelets form on inland waters. |
| 25-31 |
Large branches in motion; whistling heard in power lines; umbrella use is difficult |
