A wind vane is the common instrument used to discover wind direction. Wind vanes look like windmills mounted on a pole that allows them to rotate toward the direction of the oncoming wind. Historically, wind vanes have often come in decorative models, often with a rooster or some other farm animal mounted on the top. Of course, there are many other ways to discover wind direction, ranging from the primitive (analyzing the direction smoke is blowing or how balloons are moving) to the more sophisticated, such as Doppler sodar (sound radar) and lidar (light radar). Gyroscopes and GPS devices mounted in airplanes can calculate air speed by comparing the indicated speed to the actual distance covered (i.e., the amount of thrust from the airplane’s jets or propellers may be slowed or sped up, depending on whether winds are blowing with or against the plane).