*2.1. Vertically-Oriented Cloud Radar*

A vertically-oriented Ka-band cloud radar MIRA 35c manufactured by METEK Gmbh (http: //metek.de/) was mounted at the top of Milešovka hill (837 m a. s. l.) at a meteorological observatory (Figure 1) in Central Europe (northwestern Czechia; 50◦33 18" N and 13◦55 54" E) in March 2018. The polarimetric cloud radar (i.e., cloud profiler) works at a frequency of 35 GHz. After calibration of the instrument, the radar began operating in June 2018. Table 1 provides the reader with the technical specifications of the radar.

**Figure 1.** Placement of the cloud radar MIRA35c at the Milešovka observatory situated at the top of Milešovka hill (837 m a.s.l.) and its geographical location in Czechia in Central Europe.


**Table 1.** Technical parameters of the cloud radar MIRA35c situated at the Milešovka hill.

The cloud radar is equipped with an Interactive Data Language (IDL) software enabling the basic processing and visualization of Doppler spectra (http://metek.de/product/mira-35c/). Doppler spectra are obtained after averaging 40 consecutive values and after estimation of noise floor. Values below the estimated noise floor are considered as NaN values (they have no signal). The IDL software calculates three moments of averaged Doppler spectra such as radar reflectivity (Z), Doppler vertical velocity (DV) and spectrum width (σ). Among derived quantities, one also obtains values of Signal-to-Noise Ratio (SNR) and values of Linear Depolarization Ratio (LDR). Approximately, the radar records are available every 2 s from 509 gates. Gates are denoted ig = 4, ... , ig = 512 because the first three gates (ig = 1, ig = 2, and ig = 3), which are closest to the ground, are not processed. The distance between two consecutive gates is 28.8 m.

In this study, we use averaged noise-free Doppler spectra to estimate vertical air velocity (AV) and derive five hydrometeor species. The algorithm deriving AV as well as the algorithm classifying hydrometeors (Hclass) are described in Sections 2.2 and 2.3.
