A unit of radar reflectivity used in meteorology. The unit measures the amount of energy returned to a weather radar site as a function of the amount transmitted.

The scale is logarithmic, with a difference of 10 dB Z indicating a 10-fold increase in energy returned.

dB Z values are grouped as follows:

dB Z
Level 118-30 dBZLight precipitation
Level 230-38 dBZLight to moderate rain
Level 338-44 dBZModerate to heavy rain
Level 444-50 dBZHeavy rain
Level 550-57 dBZVery heavy rain; hail possible
Level 6>57 dBZVery heavy rain and hail; large hail possible

See also: Decibel, Radar.

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Subjects: Meteorology Units