In the early 1960s, researchers tried firing rockets trailing wires into thunderclouds to set up an easy discharge path for the huge electric charges that these clouds generate.

在20世纪60年代早期，研究人员试图将火箭尾部的电线发射到雷云中，以便于为这些雷云产生的巨大电荷建立一个简单的放电路径。

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The set will feature real grass, an oak tree and "clouds" suspended from wires above the stadium - one of which will produce rain, provided the British weather does not provide its own on the night.

BBC: London 2012: Olympics opening ceremony details revealed