In this study, photographic records of natural lightning flashes obtained from high-speed video camera observations are analyzed based on an extensive literature review. The purpose of this work is to estimate the fractal dimension of lightning discharges and to analyze and evaluate the effect of lightning type (downward and upward flashes during their propagation as well as return strokes) and lightning polarity (negative and positive). Three methods of fractal dimension estimation are employed namely the: (i) box-counting, (ii) sandbox, and (iii) correlation method, utilizing algorithms developed in MATLAB software. Appropriate image processing techniques are employed to guarantee precision in fractal dimension estimation. A thorough discussion is conducted by comparing the estimated fractal dimension values with those previously documented in the relevant literature based on field observations. The mean fractal dimension of downward negative leaders for the three methods (1.18, 1.31, 1.38) aligns well with previous studies, while positive downward leaders exhibit lower values (1.08, 1.15, 1.26), denoting a reduced branching behavior; upward leaders demonstrate slightly higher fractal dimensions than downward ones. Additionally, an attempt to correlate the lightning return stroke peak current with the fractal dimension is made. The outcomes of this research may assist in facilitating precise modeling of the lightning attachment phenomenon, thereby contributing to the development of safer lightning protection systems.

中文翻译：

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基于综合文献综述的各类雷电放电分形维数分析


在这项研究中，根据广泛的文献综述分析了从高速摄像机观测中获得的自然闪电的照片记录。这项工作的目的是估计雷电放电的分形维数，并分析和评估雷电类型（传播和返回过程中向下和向上的闪光）和雷电极性（负和正）的影响。采用三种分形维数估计方法，即：（i） 盒计数，（ii） 沙箱和 （iii） 相关方法，利用 MATLAB 软件中开发的算法。采用适当的图像处理技术来保证分形维数估计的精度。通过将估计的分形维数值与先前基于现场观察的相关文献中记录的值进行比较，进行深入的讨论。三种方法的向下负领导者的平均分形维数 （1.18， 1.31， 1.38） 与以前的研究非常一致，而正向下领导者表现出较低的值 （1.08， 1.15， 1.26），表示分支行为减少;向上的领导者表现出比向下的领导者略高的分形维度。此外，还尝试将雷电返回行程峰值电流与分形维数相关联。这项研究的结果可能有助于促进对雷电附着现象的精确建模，从而有助于开发更安全的防雷系统。