Radar, Airfield, And Weather Systems (RAWS) CDC Volume 2 Practice Test

Radar reflectivity data directly track how much precipitation is in the air and how large the falling droplets are. When the radar beam hits hydrometeors like raindrops, snow, or hail, those targets scatter more energy back to the radar if there are more of them or if they are bigger. The strength of that returned signal, called reflectivity, increases with both the number and size of the droplets, so higher reflectivity corresponds to more intense precipitation. In practice, reflectivity is related to precipitation rate through empirical relationships, often called Z-R relationships, which let us estimate how much water is falling per hour from the observed reflectivity. That direct link to how heavy the precipitation is makes it the most immediate parameter derived from reflectivity data. Wind speed, cloud color, and humidity aren’t obtained directly from standard reflectivity. Wind speed relies on Doppler velocity information to measure motion, cloud color is an optical property not captured by reflectivity, and humidity is a moisture variable that radar reflectivity doesn’t directly provide.