A subsonic wind tunnel is a testing facility designed to study the behavior of objects moving through air at speeds less than the speed of sound, typically below 343 meters per second (1,125 feet per second) at sea level. These tunnels create controlled airflow around models, allowing engineers and researchers to analyze aerodynamic properties such as lift, drag, and stability. Subsonic wind tunnels are essential in various fields, including aerospace engineering, automotive design, and architecture. They help in optimizing designs for vehicles, aircraft, and buildings by simulating real-world conditions, ultimately improving performance and safety in applications related to aerodynamics and fluid dynamics.