dB Z

   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, a difference of 10 dB Z indicating a 10-fold increase in energy returned. For display purposes, dB Z values are grouped as follows:

(Level 1, 18-30 dBZ) - Light precipitation

(Level 2, 30-38 dBZ) - Light to moderate rain

(Level 3, 38-44 dBZ) - Moderate to heavy rain

(Level 4, 44-50 dBZ) - Heavy rain

(Level 5, 50-57 dBZ) - Very heavy rain; hail possible

(Level 6, >57 dBZ) - Very heavy rain and hail; large hail possible

   The colorful "radar images" shown on television are actually plots of these levels.