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| | Thunder and Lightning |
 | | For cloud-to-ground strikes, which make up perhaps 20% of all lightning discharges, the process usually starts at the edge of the N region where the local field is great enough to enable the electrons to ionize air molecules, which is happening all the time, in which electron avalanches create a quiet, nonluminous Townsend discharge. |
 | | Lightning is actually a significant hazard, and steps should be taken not to meet it in the open. |
 | | In the 19th century, many held that the lightning bored a hole in the air, and thunder was the air filling that vacuum. |
| www.du.edu /~etuttle/weather/tstorm.htm (4946 words) |
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