We show for the first time that elves can be produced by an unusual small‐scale continental spring‐time thunderstorm. The storm occurred in Central Europe, covered a very small area of ∼50 × ∼30 km and lasted only for ∼4 h on April 2, 2017. The fraction of intense positive cloud‐to‐ground lightning strokes was unusually high, reaching 55%, with a mean peak current of 64 kA. The peak currents of return strokes (RS) associated with elves exceeded ∼300 kA. Elves and their causative RS have been observed with different optical and electromagnetic recordings. Signatures of ionospheric disturbances indicating the presence of elves were found in measurements of displacement currents, ionospheric reflections of sferics and man‐made narrow‐band transmissions. All these electromagnetic observations coincide with four optical detections of elves and strongly suggest the occurrence of two more elves later in the decaying phase of the storm. Surprisingly, the same electromagnetic measurements indicate that other strong strokes did not produce any elves. Our simulation results show that the formation of an elve is not only determined by the high‐peak current of their causative strokes but that it is also controlled by the conductivity of the lightning channels and velocity of the current wavefront. We hypothesize that because of a lower conductivity of RS lightning channels and/or slower current waves only very strong strokes with peak currents above ∼300 kA might have been capable to produce observable elves during this thunderstorm.

中文翻译：

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在一次不寻常的小规模大陆春季雷暴中，精灵及其引起的非常强烈的雷电放电的首次观测

我们首次展示了精灵可能是由不寻常的小规模大陆性春季雷暴产生的。风暴发生在中欧，覆盖约50×〜30 km很小的区域，仅持续约4 h到2017年4月2日。强烈的云对地面雷击分数异常高，达到55 ％，平均峰值电流为64 kA。与精灵相关的回程（RS）峰值电流超过〜300 kA。用不同的光学和电磁记录观察到精灵及其致病性RS。电离层扰动的特征表明存在精灵，这是在位移电流，Sferic的电离层反射和人为窄带传输的测量中发现的。所有这些电磁观测都与对小精灵的四次光学检测相吻合，并强烈暗示在风暴的衰变阶段以后还会再出现两个小精灵。出乎意料的是，相同的电磁测量结果表明，其他强击未产生任何精灵。我们的模拟结果表明，精灵的形成不仅取决于其引起冲程的高峰值电流，而且还受到雷电通道的电导率和电流波阵面速度的控制。我们假设由于RS雷电通道的电导率较低和/或电流波较慢，因此在雷暴期间只有峰值电流大于约300 kA的非常强的冲程才可能产生可观察到的精灵。