Wind Speed Scales
Da Gentle Breeze un Hurricane Force
Understand Wind CategoriesWeather reports mention "25 mph winds" o "Category 3 hurricane" o "gale force conditions." Comprendere wind speed scales helps you interpret forecasts, prepare per storms, e appreciate il power di moving air—da il gentlest breeze un devastating hurricanes.
Il Beaufort Wind Scale
Developed in 1805 da Sir Francis Beaufort per naval usare, this scale correlates wind speed con observed sea e land conditions.
| Force | Name | MPH | KM/H | Knots | Effects |
|---|---|---|---|---|---|
| 0 | Calm | 0-1 | 0-2 | 0-1 | Smoke rises vertically |
| 1 | Light air | 1-3 | 2-6 | 1-3 | Smoke drifts |
| 2 | Light breeze | 4-7 | 7-11 | 4-6 | Leaves rustle |
| 3 | Gentle breeze | 8-12 | 12-19 | 7-10 | Flags extend |
| 4 | Moderate breeze | 13-18 | 20-29 | 11-16 | Small branches move |
| 5 | Fresh breeze | 19-24 | 30-39 | 17-21 | Small trees sway |
| 6 | Strong breeze | 25-31 | 40-50 | 22-27 | Umbrellas difficult |
| 7 | Near gale | 32-38 | 51-61 | 28-33 | Walking hindered |
| 8 | Gale | 39-46 | 62-74 | 34-40 | Twigs break |
| 9 | Strong gale | 47-54 | 75-87 | 41-47 | Minor structural damage |
| 10 | Storm | 55-63 | 88-102 | 48-55 | Trees uprooted |
| 11 | Violent storm | 64-72 | 103-117 | 56-63 | Widespread damage |
| 12 | Hurricane | 73+ | 118+ | 64+ | Devastating damage |
Saffir-Simpson Hurricane Scale
Used per Atlantic e Eastern Pacific hurricanes. Based on sustained wind speed.
| Category | MPH | KM/H | Knots | Damage Potential |
|---|---|---|---|---|
| 1 | 74-95 | 119-153 | 64-82 | Minimal: some roof/siding damage |
| 2 | 96-110 | 154-177 | 83-95 | Moderate: major roof damage, trees uprooted |
| 3 | 111-129 | 178-208 | 96-112 | Extensive: devastating damage, electricity out per giorni |
| 4 | 130-156 | 209-251 | 113-136 | Extreme: severe damage, areas uninhabitable per settimane |
| 5 | 157+ | 252+ | 137+ | Catastrophic: total destruction di many buildings |
Category 3-5 sono considered "major hurricanes."
Tornado Scales
Enhanced Fujita (EF) Scale
| Rating | MPH | KM/H | Damage Descrizione |
|---|---|---|---|
| EF0 | 65-85 | 105-137 | Light: branches broken, shingles damaged |
| EF1 | 86-110 | 138-177 | Moderate: mobile homes overturned, roofs stripped |
| EF2 | 111-135 | 178-217 | Significant: roofs torn off, large trees uprooted |
| EF3 | 136-165 | 218-266 | Severe: entire stories destroyed, heavy cars thrown |
| EF4 | 166-200 | 267-322 | Devastating: well-built homes leveled |
| EF5 | 200+ | 322+ | Incredible: strong buildings destroyed, cars missiles |
Other Wind Classifications
National Weather Service Terms
| Term | Wind Speed |
|---|---|
| Wind Advisory | Sustained 31-39 mph o gusts 46-57 mph |
| High Wind Attenzione | Sustained 40+ mph o gusts 58+ mph |
| Extreme Wind Attenzione | Sustained 115+ mph |
| Tropical Storm | 39-73 mph |
| Hurricane | 74+ mph |
Marine Terms
| Term | Knots | MPH |
|---|---|---|
| Small Craft Advisory | 18-33 | 21-38 |
| Gale Attenzione | 34-47 | 39-54 |
| Storm Attenzione | 48-63 | 55-73 |
| Hurricane Force Attenzione | 64+ | 74+ |
Measuring Wind Speed
Instruments
- Anemometer: Rotating cups misurare wind speed
- Wind vane: Points into il wind per direction
- Doppler radar: Measures wind remotely
- Weather balloon: Upper atmosphere misurazioni
Sustained vs Gusts
- Sustained wind: Average over 1-2 minuti
- Gusts: Brief increases lasting secondi
Gusts typically exceed sustained winds da 30-50%.
Conclusione
Wind speed scales translate abstract numbers into meaningful descriptions di conditions e hazards. Il Beaufort scale covers everyday winds da calm un hurricane force. Il Saffir-Simpson scale categorizes tropical storms da damage potential. Comprendere these scales helps you prepare per weather events e interpret forecasts accurately.