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Lightning is a powerful
natural electrostatic discharge produced during a thunderstorm.
Lightning's abrupt electric discharge is accompanied by the emission
of light. The electricity passing through the atmosphere rapidly
heats and expands the air, producing lightning's characteristic
thunder sound. The first process in the generation of lightning
is the forcible separation of positive and negative charges within
a cloud or air. The mechanism by which this happens is still the
subject of research, but one widely accepted theory is the polarization
mechanism. This mechanism has two components: the first is that
falling droplets of ice and rain become electrically polarized
as they fall through the atmosphere's natural electric field,
and the second is that colliding ice particles become charged
by electrostatic induction. Once charged, by whatever mechanism,
work is performed as the opposite charges are driven apart and
energy is stored in the e-fields between them
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The positively
charged crystals tend to rise to the top, causing the cloud top
to build up a positive charge, and the negatively charged crystals
and hailstones drop to the middle and bottom layers of the cloud,
building up a negative charge. Cloud-to-cloud lightning can appear
at this point. Cloud-to-ground lightning is less common. Cumulonimbus
clouds that do not produce enough ice crystals usually fail to
produce enough charge separation to cause lightning. Lightning
can also occur within the ash clouds from volcanic eruptions,
or can be caused by violent forest fires which generate sufficient
dust to create a static charge.
Above Images Are From The NOAA
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