Legend information is found with a radar image and is used to display color-codes from reflectivity values found on radar images/maps. These reflectivity values can indicate the intensity of precipitation (i.e., light, moderate, heavy…)
The color of orange and red on a radar map, generally indicate heavy precipitation, which comes from thunderstorms. Yellow indicates moderate precipitation, and the color green indicates light precipitation.
For more information on how Radar “works” log onto to: http://www.nwas.org/meetings/nwa2006/Broadcast/Kane/ Radarmedianwa2.ppt#346,5,Basic Radar Operation