www.radartutorial.eu Radar Basics


Reflectivity is the amount of transmitted power returned to the weather radar receiver. It is defined as the radar cross section per unit volume for small dielectric spheres. The reflectivity Z is proportionally to the number and the size of the rain drops in a volume unit. The unit of measurement is mm6·m-3. The reflectivity depends on a lot of factors and ranges over several orders of magnitudes, so it is usually expressed on a logarithmic scale called dBZ (decibels of Z, where Z represents the energy reflected back to the radar).

All dependencies are summarized to a factor and an exponent for meteorological use, as shown in this equation:

During a long-term monitoring a number of different values are ascertained for the factor a and the exponent b. A detailed description of these values are fixed for every radar (and every radar site) in an individual table.