Wind speed generally tends to increase with height, but may not do so evenly. Sometimes, the polar jet stream will be sampled by radar, especially in winter, and low-level jets are routinely observed. In this idealized radial velocity image, the radial velocities show a maxima at the first range ring and above that wind speeds begin to decrease. This type of phenomena will typically show up on radial velocity images as two bull's-eyes that have closed isodops in some portion of the image.