Work out wind speed at hub height instantly with clear inputs, formula shown and shareable results.
The power law extrapolates wind speed with height: v2 = v1 x (h2/h1)^alpha. The shear exponent is about 0.10-0.14 over water and smooth ground, 0.20 over open farmland and 0.25-0.40 over forest and built-up terrain. Because power varies with speed cubed, a 20% speed gain gives a 73% power gain.
Power law wind shear
v2 = v1 x (h2 / h1)^alpha
Power scaling
Power ratio = (v2 / v1)^3
Because both speed and power rise with height. Going from 80 m to 120 m hub height at alpha = 0.2 adds about 8.5% speed and 28% energy, which usually outweighs the extra tower cost.
From simultaneous measurements at two or more heights on a met mast, or from lidar. It varies with time of day and stability, so annual and diurnal averages differ.