Radar data are used by scientists on computers for generating wind, wind shear, storm intensity, and hazardous weather information. Whenever you view a radar image it is most likely a reflectivity image. They paint a picture of the weather from the energy reflected back to the radar. The dBZ values you seen the map key approximate rainfall rates measured in inches/hour. As you move up the color scale, the higher you go, the more rain that is falling. <15 dBZ means no rain is falling.