Evaluating Lightning Susceptibility

摘要

They say that lightning doesn't strike the same place twice. Wrong! The Empire State building has been struck thousands of times, so often that it was used as a test object during early lightning studies. On a macroscopic level, when an object or person is struck by lightning, it probably has been struck multiple times in that single event because of the way the lightning waveform is generated. A thundercloud behaves like an electrostatic charge generator. Charge separation occurs when ice particles circulating within the cloud and bumping into one another take on or lose electrons. During collisions, small particles give up electrons to larger particles regardless of whether they are ice, dust, flour, or whatever. Because the smaller ice particles are lighter, they are blown higher in the cloud so the top of the cloud becomes increasingly more positive and the bottom more negative.