Experimental data show that the peak currents of first and subsequent lightning return strokes in negative ground flashes increase with decreasing latitude. In this paper, the reason for this dependence of peak return stroke current on latitude is explained using the fact that the height of the charge centers increases with decreasing latitude. Results show that in tropical regions where the height to the negative charge center is about 8 km, the median values of the first and the subsequent return stroke peak currents are about 42 kA and 15 kA, respectively. If the height to the charge center is larger than 8 km, the peak currents will also become larger. For example, if the location of the charge center is increased to about 9 km, the median values of the first and subsequent return stroke peak currents will increase to about 45 kA and 16 kA respectively. The same reasoning shows that, even in the same geographical region, the peak return stroke current may decrease as the elevation of the ground where the lightning strikes take place increases. The results also indicate that the peak subsequent return stroke current in tower-initiated negative lightning flashes decreases as the height of the tower increases. These theoretical predictions are in general agreement with the available experimental data.

中文翻译：

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自然和由塔引发的负地闪中雷电回击峰值电流的纬度和地形依赖性

实验数据表明，负纬向闪电中第一次和随后的雷电回击的峰值电流随着纬度的减小而增加。在本文中，使用电荷中心高度随纬度减小而增加的事实来解释峰值返回冲程电流与纬度之间这种依赖性的原因。结果表明，在到负电荷中心的高度大约为8 km的热带地区，第一个和随后的回程峰值电流的中值分别约为42 kA和15 kA。如果到充电中心的高度大于8 km，则峰值电流也将变大。例如，如果充电中心的位置增加到大约9公里，第一和随后的回程峰值电流的中值将分别增加到约45 kA和16 kA。相同的理由表明，即使在相同的地理区域，峰值雷击电流也会随着发生雷击的地面高度的增加而减小。结果还表明，随着塔架高度的增加，塔架引发的负向闪电的峰值后续回程电流减小。这些理论预测与现有的实验数据基本一致。结果还表明，随着塔架高度的增加，塔架引发的负向闪电的峰值后续回程电流减小。这些理论预测与现有的实验数据基本一致。结果还表明，随着塔架高度的增加，塔架引发的负向闪电的峰值后续回程电流减小。这些理论预测与现有的实验数据基本一致。