[meteorology] dBZ stands for decibels relative to Z. It is a logarithmic dimensionless technical unit used in radar, mostly in weather radar, to compare the equivalent reflectivity (Z) of a radar signal reflected off a remote object (in mm6 per m3) to the return a droplet of rain with a diameter of 1 mm (1 mm6 per m3). It is proportional to... Found on http://en.wikipedia.org/wiki/DBZ_(meteorology)