Reflectivity of an object helps indicate the amount of water that a cloud may carry.
The stronger the reflected signal from the radar signal sent out, the easier the meteorologist will be able to tell what to expect. These signals have been calibrated against actual visual and location readings for the amount of rain falling and cloud water content.
The computer is very good at allowing colors to be assigned to values generated by the returning radar signal. Thus the computer generates a visual image according to the reflectivity of the amount of water in colors on a map.
This in turn is interpreted by the meteorologist from past experience as what to expect in the future.
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