Logarithmic profile · height-dependent wind speed & dynamic pressure
| Class | z₀ | Land Cover Type |
|---|---|---|
| 0 | 0.0002 | Water surfaces: seas, lakes |
| 0.5 | 0.0024 | Open flat terrain, concrete, runways |
| 1 | 0.03 | Open agricultural land, no fences |
| 1.5 | 0.055 | Agricultural land w/ sparse buildings |
| 2 | 0.1 | Agricultural land w/ buildings & hedges |
| 2.5 | 0.2 | Wooded agricultural land, many trees |
| 3 | 0.4 | Towns, villages, forests, rough terrain |
| 3.5 | 0.6 | Large cities with tall buildings |
| 4 | 1.6 | Metropolis with skyscrapers |
| Height | Speed | Pressure | kg/m² |
|---|
The Wind Profile Calculator uses the logarithmic boundary-layer law to compute wind speed and dynamic pressure at any height from a known reference speed at a reference height. It is free to use and requires no registration.
v₂ = v₁ · ln(h₂/z₀) / ln(h₁/z₀): v₁ is the known speed at reference height h₁, v₂ the speed at target height h₂, and z₀ the roughness length.q = ½ · ρ · v² (ρ ≈ 1.225 kg/m³ standard air density; adjustable in the tool)q / 9.80665The roughness length (z₀) is chosen from a 9-step scale in the tool, from 0 (water surfaces, z₀ = 0.0002 m) to 4 (metropolis with skyscrapers, z₀ = 1.6 m), the same boundary-layer logic that feeds into EN 1991-1-4 wind-engineering practice.
With the tool's default inputs (reference height 10 m, reference speed 5 m/s, roughness class 2 → z₀ = 0.1 m, ρ = 1.225 kg/m³), the calculation proceeds step by step:
| Step | Operation | Result |
|---|---|---|
| ln(h₁/z₀) | ln(10 / 0.1) | 4.605 |
| Speed at 150 m | 5 × ln(150/0.1) / 4.605 | 7.94 m/s |
| Speed at 100 m | 5 × ln(100/0.1) / 4.605 | 7.50 m/s |
| Dynamic pressure at 150 m | 0.5 × 1.225 × 7.94² | 38.6 Pa (≈3.94 kg/m²) |
These are the exact figures shown in the "150m Speed / 150m Pressure" boxes and the detailed results table when you open the tool with its default settings.
From profile to load (peak velocity pressure, zone coefficients, codes) is explained step by step in our wind load calculation guide.
To calculate facade wind load including pressure coefficients, see the Alkazar WindCalc module; for complex geometry and surroundings, see our Structure Wind Consultancy service.
The explanation on this page is for general information and does not replace project-specific engineering services. Final values should be determined under the currently applicable edition of the relevant standard.