Strength
|
Values
|
Effect on Land
|
Effect on Ocean
|
Still
|
0-19 km/h
|
Wind felt on face; leaves rustle;
|
Sea like a mirror with small wavelets forming but not breaking, a glassy appearance
is maintained.
|
Light
|
20-29 km/h
|
Raises dust and loose paper; small branches are moved.
|
Small waves - becoming longer; fairly frequent white horses.
|
Medium
|
30-39 km/h
|
Small trees in leaf begin to sway; crested wavelets form on inland waters
|
Moderate waves, taking a more pronounced long form; many white horses are formed
- a chance of some spray
|
Strong
|
40-49 km/h
|
Large branches in motion; whistling heard in telephone wires; umbrellas used with
difficulty.
|
Large waves begin to form; the white foam crests are more extensive with probably
some spray
|
X-Strong
|
50 km/h +
|
Whole trees in motion; inconvenience felt when walking against wind.
|
Sea heaps up and white foam from breaking waves begins to be blown in streaks along
direction of wind.
|