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Radar Reflectivity

Reflectivity indicates the size and amount of "stuff" in the air. This "stuff" could include water droplets, ice crystals, or even insects! Areas with relatively large particles are warm-colored (red and orage) and areas with smaller particles are cool-colored (blue and green). You'll notice that there tend to be larger particles are in the middle of the cloud and smaller particles around the edges of the cloud. The radar can only "see" particles that are within a certain size range. Therefore, a reflectivity image may not show things like fog, which is made up of extrememly small particles.