Wind atmosphere based upon how far clouds move from one image to the next. Wind engineering describes the study of the effects of the wind on the built environment, including buildings, bridges and other man-made objects. Historically, the Beaufort wind force scale (created by Beaufort) provides an empirical description of wind speed based on observed sea conditions. Originally it was a 13-level scale, but during the 1940s, the scale was expanded to 17 levels. There are general terms that differentiate winds of different average speeds such as a breeze, a gale, a storm, tornado, or a hurricane. Within the Beaufort scale,
Wind tunnel high Reynolds number, since it is not practical to obtain full scale Reynolds number by use of a full scale vehicle. V/STOL tunnels require large cross section area, but only small velocities. Since power varies with the cube of velocity, the power required for the operation is also less. An example of a V/STOL tunnel is the NASA Langley 14' x 22' tunnel. Aircraft have a tendency to go to spin when they stall. These tunnels are used to study that phenomenon. Automotive wind tunnels fall into two categories: Wunibald Kamm built the first full-scale wind tunnel for motor vehicles.