In the present study, frequency spectra of the electric field corresponding to the various cloud events, such as, initial breakdown process, regular pulse bursts, chaotic pulse trains and recoil streamers have been analysed. For the purpose, electric field radiated by cloud flashes were obtained simultaneously by a wide bandwidth antenna system and two narrow bandwidth antenna systems tuned at 3 MHz and 30 MHz. The frequency spectra of the broad band electric field signatures were obtained by using the wavelet transform technique and were compared with the magnitudes of the narrow band signals at the given central frequencies. To the best of our knowledge, it is the first study in which frequency spectra is obtained by transforming the time domain signal using wavelet transform technique and ratified by narrow bandwidth system for the cloud flashes. Fifteen cloud flashes pertinent to the Swedish thunderstorms were selected for the purpose. It is found that, the cloud flashes radiate at frequencies as low as 3 kHz to as high as a few tens of Mega Hertz (MHz). Electric field radiation corresponding to the initial breakdown process were found to radiate in the frequency range of 50 kHz to 5 MHz on the average, maximum energy is being radiated in the frequency range of 500 kHz to 5 MHz. Similarly, the final stage corresponding to the regular pulse bursts was found to radiate in the frequency range of 50 kHz to 5 MHz and that corresponding to the chaotic pulse trains was found to be in the range of 100 kHz to 5 MHz. Whereas, the very narrow pulses at the final stage, that can be termed as pulses corresponding recoil streamers (or Q-streamers) were found to radiate in the frequency range of 50 kHz to well above 10 MHz. Q-streamers can be considered as the strongest source of very high frequency and is justified by the simultaneous measurement of the electric fields at very high frequency (30 MHz) narrow bandwidth system. Rectification of the biasness of the conventional wavelet power spectrum has also been performed, however, no significant change in the spectrum was observed. Therefore, this study provides a strong basis for applying the wavelet transform technique without employing large number of narrowband system to acquire frequency domain information of lightning phenomena.

在本研究中，已经分析了与各种云事件相对应的电场频谱，例如初始击穿过程，规则脉冲爆发，混沌脉冲序列和后坐力拖缆。出于此目的，由宽带闪光系统和两个调谐在3 MHz和30 MHz的窄带宽天线系统同时获得了由云闪光辐射的电场。通过使用小波变换技术获得宽带电场信号的频谱，并将其与给定中心频率下的窄带信号幅度进行比较。据我们所知，这是第一项通过使用小波变换技术对时域信号进行变换并通过窄带系统对云闪进行批准而获得频谱的研究。为此，选择了与瑞典雷暴有关的十五次云闪。结果发现，云朵闪烁的辐射频率低至3 kHz至几十兆赫兹（MHz）。发现对应于初始击穿过程的电场辐射平均在50 kHz至5 MHz的频率范围内辐射，最大能量在500 kHz至5 MHz的频率范围内辐射。相似地，发现对应于常规脉冲猝发的末级在50kHz至5MHz的频率范围内辐射，并且发现对应于混沌脉冲串的末级在100kHz至5MHz的范围内辐射。然而，发现最后阶段的非常窄的脉冲（可以称为脉冲）对应于后坐拖缆（或Q拖缆）在50 kHz至远高于10 MHz的频率范围内辐射。Q流可以被认为是极高频率的最强信号源，并且通过同时测量极高频率（30 MHz）窄带宽系统中的电场是合理的。还已经对常规小波功率谱的偏置进行了校正，但是，未观察到谱的显着变化。所以，