Wind observations
- Direction and velocity of wind can be measured accurately by means of instruments or they may be estimated by direct observations.
- The direction from which a wind blows is called windward and the direction towards which it blows is called leeward.
- Rough indications of wind velocity at 2 m height when the surrounding is flat, open terrain are given by the Beaufort scale. This can also be used if instruments are not available.
|
Wind speed (km/hr) |
Name |
Indicator conditions |
|
<1 |
Calm |
Smokes rise vertically |
|
1-5 |
Light air |
Smoke drifts and leaves rustle |
|
6-11 |
Light breeze |
Wind felt on face |
|
12-19 |
Gentle breeze |
Flags extended; leaves move |
|
20-29 |
Moderate breeze |
Dust and small branches move |
|
30-39 |
Fresh breeze |
small trees begin to sway. |
|
40-50 |
Strong breeze |
Large branches move, wires whistle, umbrellas are difficult to control |
|
51-61 |
Near gale |
Whole trees in motion, inconvenience in walking. |
|
62-74 |
Gale |
Difficult to walk against wind. Twigs and small branches blown off trees |
|
75-87 |
Strong gale |
Minor structural damage may occur (shingles blown off roofs) |
|
88-102 |
Storm |
Trees uprooted, structural damage likely |
|
103-118 |
Violent storm |
Widespread damage to structures |
|
119+ |
Hurricane |
Severe structural damage to buildings, wide spread devastation |