Roughness Length
The roughness classes are defined as roughness length in meter (z0), which results to the height above ground level where the wind speed is theoretical zero.
| Roughness Class | Roughness Length, z0 in m | Energy Index (%) | Land Scape | |
|---|---|---|---|---|
0 | 0.0002 | 100 | Water surface | |
0.5 | 0.0024 | 73 | Open terain with smooth surface i.e. runways | |
1 | 0.03 | 52 | Agricultural area, no fences or hedges, scattered buildings, | |
1.5 | 0.055 | 45 | Agricultural area, some houses, hedges with min. 1250m/¾ mile distance | |
2 | 0.1 | 39 | Agricultural area, couple of houses, hedges with min. 500m/¼ mile distance | |
2.5 | 0.2 | 31 | Agricultural area with houses, shrubs, trees and hedges with min. 250m distance | |
3 | 0.4 | 24 | Villages, small towns forests or very rough and uneven terain | |
3.5 | 0.8 | 18 | Lager cities with tall buildings | |
4 | 1.6 | 13 | Very large cities with tall buildings |
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