windgradient

Windgradient refers to the spatial variation of wind speed and/or direction over a distance, most commonly with height in the atmospheric boundary layer but also across horizontal space influenced by terrain, water bodies, or urban structures. It encompasses vertical wind shear—the change of wind with altitude—and horizontal wind gradients caused by surface roughness, obstacles, or land–sea transitions. The term often appears in meteorology, wind engineering, and environmental modeling to describe how the wind field changes over a given domain.

Vertical wind gradients are a key aspect of atmospheric wind profiles. In the lower atmosphere, mean wind speed profiles are frequently modeled using logarithmic or power-law relations, which express how speed increases with height. The rate of change of wind velocity with height is called wind shear, and it has practical implications for aviation, weather forecasting, and dispersion of pollutants. Directional changes with height, or directional wind shear, can also occur and affect gusts and rotor loading for wind turbines.

Measurement and modeling approaches include tall meteorological towers with multiple anemometers, lidar or sodar instruments, and radiosonde releases. In neutral stability, the logarithmic wind profile Uf(z) = (u*/k) ln(z/z0) provides a common reference, where u* is the friction velocity, k is the von Karman constant, and z0 is roughness length. Real-world gradients vary with atmospheric stability, time of day, and surface characteristics.

Applications are widespread: in wind energy, wind gradients influence turbine performance and structural loads; in aviation, they relate to wind shear hazards during takeoff and landing; and in dispersion modeling, gradients affect pollutant mixing and transport.