CHMI Radar Network

Principle of weather radar is based on backscattering of microwaves (cm-waves) on water droplets and ice particles in precipitation and clouds. Transmitter generates short high-energy pulses of microwave, which are transmitted by antenna in the form of narrow (pencil shape) beam into the atmosphere. Part of the energy is "reflected" (exactly : scattered back) by meteorological (precipitation, clouds) or other (earth surface, aircraft, ...) targets. Part of the reflected energy is detected by receiver. Target position is determined using the position (elevation angle and azimuth) of the antenna and time interval between the transmission of the pulse and the reception of the reflected signal. Intensity of the reflection is proportional to the radar reflectivity of the target.

Typically, weather radar measurements are volumetric: approximatelly 15-20 PPI's ( = azimuth rotations of antenna with various elevation angles ). Measurements are repeated every 5-15 minutes.