LIGHTNING
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LIGHTNING |
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The phenomenon of lightning is actively investigated since 1752, when the American statesman and scientist B.Franklin one of the first established the electrical nature of lightning. As a whole the picture of formation of
lightning
is as follows. The terrestrial atmosphere is very good dielectric located between two conductors - a surface of the ground from below and the top layers of an atmosphere, including an ionosphere, from above. These layers are passive components of a global electric circuit. Between negatively charged surface of the ground and positively charged top atmosphere the constant potential difference of about 300.000 V is supported. According to the idea for the first time stated by Wilson in 20th years this ionosphere potential arises from thunder-storms which create global electric "battery".
Lightning is a visible electric charge coming
from a cloud, going to either another cloud or the earth. Usually, thunder like the sound you are hearing accompanies lightning,
especially during a thunderstorm. Lightning occurs because the bottom of a
thundercloud becomes negatively charged, and repels the negative charge of the
ground deeper in so the positive charge is more towards the surface. Simple physics says that opposite charges attract, so boom, the lightning takes
a one way trip to the closest positively charged item- usually a tree, phone
pole, or other high object. Despite of an abundance at present of new devices and methods of research, the microphysical processes leading to charge of storm clouds, remain a subject of disputes.
One of hypothesis, illustrated in animation, connects the lightning appearance with solar activity. The Earth’s upper atmosphere interacts with high energy particles from the sun (called the solar wind) to produce a steady stream of positive ions, which, in turn, rain down onto the Earth’s surface. Nevertheless, the Earth’s total average surface charge does not change. The increase in the Earth’s positive surface charge is cancelled out by the flow of negative electrons from the clouds to the ground during electrical storms. A lightning bolt can deliver a current of 10 million amperes to the Earth’s surface. Electrical storms are connected to solar activity. The sun’s activity peaks every 11 years. When solar wind activity is greater, more positive ions are produced by the solar wind. Thus, more electrical storms are induced on Earth to cancel the increased positive ion flow.
