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Wind Shear Calculator — Complex / Hilly Terrain

Extrapolate wind speed to hub height over complex / hilly terrain (Hellmann α≈0.25) with the cube-law power impact.

Power-law extrapolation degrades in complex terrain — ridge acceleration and flow separation defeat simple α; treat results as a first guess only. Enter any measured speed and height; the power-law profile scales it to hub height and shows the cubed effect on power density.

10.67 m/s
Wind speed at 100 m
Speed ratio× 1.78
Power density ratio× 5.62 (cube law)
Hellmann power lawv₂ = v₁ × (h₂/h₁)^0.25

The power-law profile is why hub heights keep growing: raising hub height from 80 to 120 m over cropland (α≈0.2) adds ~8% wind speed — but ~27% more power. Measure α on site from two anemometer heights when possible; tabulated values mislead in complex terrain.

Sources: Hellmann power-law wind profile; terrain exponent tables

Engineering estimate from published standards and typical equipment data. Site conditions, equipment datasheets and measured data govern the real result — confirm with a qualified engineer.

Use the free Wind Shear Calculator — Complex / Hilly Terrain online — Extrapolate wind speed to hub height over complex / hilly terrain (Hellmann α≈0.25) with the cube-law power impact. Runs instantly in your browser: no signup, no upload, mobile-friendly.

About Wind Shear Calculator — Complex / Hilly Terrain

Power-law extrapolation degrades in complex terrain — ridge acceleration and flow separation defeat simple α; treat results as a first guess only. Enter any measured speed and height; the power-law profile scales it to hub height and shows the cubed effect on power density.

How to use Wind Shear Calculator — Complex / Hilly Terrain

  1. 1Enter a measured wind speed and its measurement height.
  2. 2Set the target (hub) height and the terrain exponent.
  3. 3Read the extrapolated speed and the power-density multiple.

Why use Wind Shear Calculator — Complex / Hilly Terrain?

  • Hellmann power-law with terrain-correct exponents
  • Cube-law power impact shown alongside the speed change
  • Terrain presets from open sea to city suburbs
  • Explains tall towers in one calculation

Frequently asked questions

How does wind speed change with height?+

By the power law v₂ = v₁(h₂/h₁)^α, with α from ~0.10 offshore to ~0.30 over suburbs. Going 10 m → 100 m over farmland (α=0.2) multiplies speed ×1.58 — and power ×3.9, because power cubes the speed. Height is the cheapest wind upgrade there is.

What shear exponent should I use?+

Open sea 0.10, open plains 0.14 (the classic 1/7th law), cropland with hedges 0.20, forest/suburb 0.25–0.30. Best practice: derive α from two measurement heights on site — tabulated values mislead in complex terrain, where the power law itself degrades.

Can I use airport wind data for my site?+

As a starting estimate: airports measure at 10 m in open terrain. Extrapolate to your hub height with the right α — then remember your terrain differs from the airport's. For investment decisions, nothing replaces on-site measurement; for screening, this is the honest first pass.

Why are wind turbine towers getting taller?+

The shear math: each terrain has more speed higher up, and the cube law triples small speed gains into big energy gains. Over forested or built terrain (high α), a 140 m tower can harvest economic wind where an 80 m tower can't — towers are buying α^cubed.

Embed Wind Shear Calculator — Complex / Hilly Terrain on your website

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