What phenomenon causes the surface wind to veer after sunset?

The phenomenon that causes the surface wind to veer after sunset is primarily related to the solidification of the friction layer. After sunset, the ground cools rapidly, leading to a cooling of the air near the surface. This cooling effect creates a stable layer of air near the surface that can influence the wind direction.

As the surface cools, the frictional effects that are usually present during the day diminish, allowing winds that were influenced by the daytime heating and local features to become less turbulent and start veering, or changing direction. The reduction of turbulence and changes in the thermal structure of the boundary layer can lead to a more organized flow of air at the surface, resulting in a noticeable veering of the wind.

This can be contrasted with other factors, such as increased wind speed or changes in altitude, which do not directly explain the veering effect as cohesively as the dynamics associated with the solidification of the friction layer.