At 100 m the wind is about 6.9 m/s (power law) or 6.98 m/s (log law), 38% faster than at 10 m, which means roughly 2.63× the wind power. Both laws agree well for this case.
Speed at 100 m (power law)
6.9m/s
α = 0.14
Speed at 100 m (log law)
6.98m/s
z₀ = 0.03 m
Speed ratio v₂/v₁
1.38
log law 1.396
Wind power gain (∝ v³)
2.63×
log law 2.72×
Equivalent α of log profile
0.145
between your two heights
Friction velocity u*
0.353m/s
neutral log-law, κ = 0.41
Speed in km/h
24.8km/h
15.4 mph · 13.4 kn
Wind speed at standard heights
| Height (m) | Power law (m/s) | Log law (m/s) | Power vs measured |
|---|---|---|---|
| 2 | 3.99 | 3.61 | 0.51× |
| 5 | 4.54 | 4.4 | 0.75× |
| 10 (measured) | 5 | 5 | 1× |
| 20 | 5.51 | 5.6 | 1.34× |
| 30 | 5.83 | 5.95 | 1.59× |
| 40 | 6.07 | 6.19 | 1.79× |
| 50 | 6.26 | 6.39 | 1.97× |
| 60 | 6.43 | 6.54 | 2.12× |
| 80 | 6.69 | 6.79 | 2.39× |
| 100 (target) | 6.9 | 6.98 | 2.63× |
| 120 | 7.08 | 7.14 | 2.84× |
| 140 | 7.23 | 7.27 | 3.03× |
| 150 | 7.31 | 7.33 | 3.12× |
| 160 | 7.37 | 7.39 | 3.2× |
| 180 | 7.49 | 7.49 | 3.37× |
| 200 | 7.61 | 7.58 | 3.52× |
- Both laws describe the average neutral profile over flat, homogeneous terrain. Hills accelerate flow on crests (speed-up 10–40%), and stable nights can produce much steeper shear (α 0.3–0.5).
- The 1/7 (α = 0.143) rule of thumb comes from open flat land; forests and towns have far higher α.