Wind Speed At Height Above Surface In Form Of Near Surface Wind Profile Calculator

Wind Speed Formula:

\[ U = \frac{V_f}{k} \times \left( \ln\left(\frac{Z}{z_0}\right) - \phi \times \frac{Z}{L} \right) \]

Friction Velocity (Vf):

m/s

Von Kármán Constant (k):

Height z above Surface (Z):

Roughness Height of Surface (z0):

Universal Similarity Function (φ):

Parameter with Dimensions of Length (L):

Wind Speed (U):

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1. What is the Wind Speed at Height above Surface Formula?

The Wind Speed at Height above Surface formula estimates wind speed at a specific height above the surface using the logarithmic wind profile law with thermal stratification correction. It provides a more accurate assessment of wind speed distribution in the atmospheric boundary layer.

2. How Does the Calculator Work?

The calculator uses the Wind Speed formula:

\[ U = \frac{V_f}{k} \times \left( \ln\left(\frac{Z}{z_0}\right) - \phi \times \frac{Z}{L} \right) \]

Where:

\( U \) — Wind Speed (m/s)
\( V_f \) — Friction Velocity (m/s)
\( k \) — Von Kármán Constant (-)
\( Z \) — Height z above Surface (m)
\( z_0 \) — Roughness Height of Surface (m)
\( \phi \) — Universal Similarity Function (-)
\( L \) — Parameter with Dimensions of Length (m)

Explanation: The equation accounts for the logarithmic wind profile with correction for thermal stratification effects in the atmospheric boundary layer.

3. Importance of Wind Speed Calculation

Details: Accurate wind speed estimation is crucial for wind energy assessment, atmospheric dispersion modeling, building design, and meteorological studies.

4. Using the Calculator

Tips: Enter all parameters with appropriate units. All values must be valid positive numbers. The Von Kármán Constant is typically around 0.4 for atmospheric applications.

5. Frequently Asked Questions (FAQ)

Q1: What is the typical value of the Von Kármán Constant?
A: The Von Kármán Constant is typically approximately 0.4 for atmospheric boundary layer applications.

Q2: How does surface roughness affect wind speed?
A: Higher surface roughness (larger z0) reduces wind speed at a given height due to increased friction and turbulence.

Q3: What does the Universal Similarity Function represent?
A: The Universal Similarity Function characterizes the effects of thermal stratification on the wind profile, accounting for stable and unstable atmospheric conditions.

Q4: When is this formula most accurate?
A: This formula is most accurate in the surface layer (lowest 10% of the boundary layer) under near-neutral to moderately stratified conditions.

Q5: What are typical roughness heights for different surfaces?
A: Water surfaces: 0.0001-0.001m, Grass: 0.01-0.1m, Crops: 0.1-0.3m, Forests: 0.5-2.0m, Urban areas: 1.0-4.0m.