Wind speed and altitude
The anemometer located at the highest point above the ground will measure the highest wind speed.
Wind speed gradient
The variation of horizontal wind speed with height or altitude is known as wind speed or shear wind. This variation in wind speed is due to aerodynamic drag. The wind speed increases as the height above the ground increases. This is caused by surface friction.
Wind that flows near the earth’s surface encounters obstacles like trees, buildings and hills that will alter its direction. Wind can change both horizontally and vertically resulting in wind turbulence near the surface of the ground.
Wind turbulence causes dust to be picked up and displaced, as well as helps in the seed dispersion of some plants. However, energy is also lost in this process, causing the wind to lose speed. Therefore, the terrain, depending on its roughness or smoothness, will have an effect on the wind speed gradient. A smooth surface like water will have a lower wind speed gradient as compared to rough ground surfaces.