How do wind velocities at 400 ft AGL typically compare to those near the surface?

At 400 feet Above Ground Level (AGL), wind velocities typically tend to be greater than those experienced near the surface. This phenomenon occurs due to the influence of terrain and friction on wind patterns. Near the surface, wind speeds are often reduced because of obstacles like buildings, trees, and the surface roughness, which create turbulence and drag.

As you ascend to 400 feet, the impact of these surface-level obstacles diminishes, resulting in smoother, more uniform wind flow. The increase in wind velocity with altitude is a key aspect of understanding atmospheric behavior, particularly relevant for unmanned aircraft operations.

Thus, the assertion that wind velocities at 400 feet AGL are generally quite higher than surface winds reflects an understanding of how atmospheric layers interact and how wind speeds can change with elevation, reinforcing the need for operators to be aware of and consider these variances during flight planning.