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A standard radar display is basically a map with the radar reflectivity superimposed. Usually it's quite easy to tell the location of the radar from the pattern of echo. Look for a spot where the reflectivity dots are small and noisy. Often there will be a few specks of high-intensity echo where the radar is picking up a signal reflected from the nearby ground or buildings.
The lowest elevation angle used by the NEXRAD radars is 0.5 degrees. This means that on their lowest scan, the radar is tilted about a half a degree above the horizon. Because of this angle, and because the Earth is curved, the farther the beam is from the radar site, the higher it will be above the ground. Thus, under different circumstances, the radar plot gives you information as a function of location and information as a function of height.
For example, in a typical widespread precipitation event, there are patches of rain all over the place. The low-level reflectivity scan will intercept most of the patches of rain, and will show you exactly where the rain is.
Meanwhile, the wind tends to be spatially uniform over the distances observed by the radar, but might vary considerably with height. The velocity pattern will therefore vary as a function of distance from the radar: as the beam gets farther from the radar, it's sampling winds at higher and higher elevations.
It's pretty easy to look at a radar image and see where the heaviest precipitation is likely to be. You don't need this module to teach you that. What you do need this module for is to teach you how to tell the difference between echo that's precipitation and echo that's something else. It would be rather embarrassing to forecast rain on the basis of a strong echo to the west, only to learn later that what the radar was actually seeing was Pikes Peak.
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