Using high-speed photography, scientists have determined that there are two steps to the occurrence of lightning from a cloud to the ground.
利用高速摄影技术，科学家们已经确定了闪电从云层到达地面有两个步骤。
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Each day, the Crew Earth Observations team at NASA's Johnson Space Center sends specific ground targets for photography to astronauts on the International Space Station (ISS).