ESTIMATE WIND SPEED
AT A HEIGHT ABOVE YOUR MEASUREMENT HEIGHT
This calculator with estimate the wind speed increase above your anemometer or weather station based on characteristics of your local terrain and topography.  Its results are based on an industry standard approximation of atmospheric boundary layer formula below.
INPUTS: Measurement Height of Wind Speed in meters = m ft ads
Measured Wind Speed [m/s] = m/s mph
Roughness Lenth from Table bellow [m]  =
m ft
Height at which to Estimate wind speed [m] = m ft
OUTPUT: ANSWER: Estimated wind speed
at desired height above ground [m/s] =
m/s mph
barani.biz  - High accuracy affordable instrumentation for wind energy evaluation and wind site assessment.
Roughness Class RC Roughness Length, Z_0 [m] Energy Index [%] Local Terrain Type, Landscape,
Topography, Vegetation
 
0 0.0002 100 Water surface.  
0.5 0.0024 73  Completely open terrain with a smooth surface, such as concrete runways in airports, mowed grass.  
1 0.03 52 Open agricultural area without fences and hedgerows and very scattered buildings.  Only softly rounded hills.  
1.5 0.055 45 Agricultural land with some houses and 8
meter tall sheltering hedgerows within a
distance of about 1250 meters.
 
2 0.1 39 Agricultural land with some houses and 8
meter tall sheltering hedgerows within a
distance of about 500 meters.
 
2.5 0.2 31 Agricultural land with many houses, shrubs
and plants, or 8 meters tall sheltering
hedgerows within a distance of about 250
meters.
 
3 0.4 24 Villages, small towns, agricultural land with
many or tall sheltering hedgerows, forests
and very rough and uneven terrain. 
 
3.5 0.8 18 Larger cities with tall buildings.  
4 1.6 13 Very large cities with tall buildings and sky scrapers.  
ROUGHNESS CLASSES AND LENGTHS
Roughness classes and roughness lengths are characteristics of the landscape used to evaluate wind conditions at a potential wind turbine site.
A sea surface has a roughness class of zero.
A high roughness class of 3-4 characterizes landscapes dotted with trees and buildings.
Concrete runways at airports and road surfaces have a roughness class of 0.5 along with flat and open landscape grazed by cattle and livestock.
The roughness length is defined as the height above ground (Z) in meters at which the wind speed is theoretically equal to zero.
The Roughness Classes (RCs) are defined in terms of the roughness length in meters Z_0.
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