Radar Sounders
A doppler radar measures some information about winds (on top of the usual echo strength all radars measure) by using the Doppler effect. Although many radars are "Doppler", this additional information is almost never shown to the public because it can be difficult to interpret even for experienced meteorologists. The most common wind information measured by a Doppler radar is the radial velocity, which is the component of the wind going in the direction of the radar (either towards or away). If we take the example of a constant wind from the north, strong approaching velocities will be observed when the radar looks north, strong receding velocities when the radar looks south, and no velocity when the radar looks east or west. This information can then be displayed, generally using progressively colder colors (for example blue) for increasingly strong approaching velocities and progressively warmer colors (for example red) for increasingly strong receding velocities. Additional information available at "http://www.radar.mcgill.ca/define_doppler.html" [Summary provided by McGill University]
XPOL