Wind Speed At Height
Calculator
Results
- Wind speed (m/s)
- 8.027565
- Wind speed (km/h)
- 28.899235
- Speed ratio vs reference
- 1.337927
Weather results
| Wind speed (m/s) | 8.027565 |
| Wind speed (km/h) | 28.899235 |
| Speed ratio vs reference | 1.337927 |
formula-map diagram
- Wind speed (m/s)
- 8.027565
- Wind speed (km/h)
- 28.899235
- Speed ratio vs reference
- 1.337927
Weather relationship
Formula
v = v₀ × (h ÷ h₀)^α (power law wind profile, α ≈ 1/7 over open terrain)= 8.0275653287167
Note
This is a simplified model: it applies the published standard formula to the numbers you entered and ignores local terrain, radiation, precipitation type and instrument error. Wind chill is the 2001 NWS/Environment Canada regression, valid at or below 10 °C with wind at or above 4.8 km/h; the heat index is the Rothfusz regression, reliable above about 27 °C; dew point uses the Magnus approximation (a = 17.27, b = 237.7 °C) over liquid water; wet bulb uses Stull's approximation at standard sea-level pressure; pressure and density altitude assume the International Standard Atmosphere and dry air. Do not use these results for aviation, structural or safety decisions without an official forecast or a qualified professional.
More in Weather and climate
See all →Frequently asked questions
Why does wind speed change with height above the ground?+
Friction from the ground surface (buildings, trees, terrain roughness) slows wind near the surface, and that slowing effect diminishes with height, so wind speed generally increases the higher above ground you measure, up to the point where surface friction no longer has much influence.
How is wind speed at a new height calculated from a known reference height?+
Common methods use a power law formula: wind speed at the target height equals the reference wind speed multiplied by the ratio of the two heights raised to a terrain-dependent exponent, typically around 0.14 for open, flat terrain and higher for rougher terrain like forests or cities.
Why does the terrain roughness exponent matter so much?+
A higher exponent means wind speed increases more sharply with height because the surface is dragging down near-ground wind more strongly (as over a forest or city), while a lower exponent means near-surface wind is already close to the wind speed higher up (as over open water or flat, smooth terrain).
Why is this calculation important for wind turbine planning?+
Wind turbine output depends heavily on wind speed at hub height, which is usually much higher than standard 10-metre weather station measurement height, so accurately extrapolating from a ground-level measurement to turbine height is essential for realistic energy yield estimates.
Does this power-law extrapolation work at any height or condition?+
No, it's an approximation that works reasonably well within the atmospheric boundary layer under typical conditions, but becomes less reliable during very stable or very unstable atmospheric conditions, and isn't meant to extrapolate to extreme heights far beyond the range it was validated for.