The results of multi-frequency measurements of clear sky and clouds apparent temperatures

A New Approach in Hail Prevention Technique for a Locally Restricted Area

“…with connected input/output terminals connects the output of the compensation device (16) with an input of the single-channel thresholder (24). The singlechannel thresholder compares output signals of the compensation device with the "alert" threshold level and generates an alerting code-signal if the input signal exceeds the "alert" threshold and the signal "0" otherwise.…”

“…Corresponding thresholds values in Volts depend on structure and technical parameters of utilized radiometric receivers (6) and (15) and may be defined from the results of theoretical estimations or from the results of experimental measurements and calibrations. "Maximum", "minimum" and "alert" thresholds levels may be corrected and may be changed individually during the exploitation of the anti-hail protection system (1) by controlled thresholders (8), (17) and (24).…”

“…In Figure 5 frequency dependences of "maximum" and "minimum" threshold levels are presented, where the curve of "minimum" threshold level corresponds to radiometric contrasts frequency dependence of cumulonimbus caused a rainfall with rare hail stones. "Minimum" values of radiometric contrasts of Figure 5 were estimated and approximated from the results of multi-frequency and dual polarization (vertical and horizontal) radiometric measurements carried out under elevation angles 20˚ and 30˚ of sensing [18]- [24] and from the known theory of passive microwave (radiometric) remote sensing. Theoretical approximations show that these curves are acceptable for elevation angles from the interval 0˚ -30˚ as well.…”