Doppler radar: A radar system used to measure the relative velocity of the system and the radar target. The operation of these systems is based on the fact that the Doppler frequency shift in the target echo is proportional to the radial component of target velocity. This type of imaging is seen quite often in Florida during hurricane season. The above image is of Hurricane Frances as it passed through South Florida.

http://pws.prserv.net/gsabbi/BergenSkywarn/Pages/BergenSkywarnHurricane2004.htm