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What is lightning
and what causes it?
|
Lightning: any form of visible electric discharge between rain clouds or between a rain cloud and the earth.
Ok, so we know the definition of lightning, but what exactly does it mean? How do we interpret this meaning for a better understanding of this natural phenomena? There is one phrase that sums up the definition of lighting: Electrical Charge
The Electrical Charge in a thundercloud is the first step in the formation of lighting. After all, Lighting is visible electric 'discharge.'
As of today, scientists still don't have a clear explanation for the formation of electrical charge in a thundercloud. Nevertheless, there are still several hypotheses pertaining to the formation of the electrical charge.
Most thunderclouds are negatively charged at the base and positively charged at the top. The various hypotheses that explain how the polarization (the formation of opposite charges) occurs may be divided into two categories: those that require ice and those that do not. However, most meteorologists today do believe ice is a necessity in the formation of lighting primamrily due to the fact that lightning is not usually observed until ice has formed in the upper layers of thunderclouds. Ice plays a big role in the different electrical charges in a thundercloud.
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Some Important Basics - Water generally consists of a positive charge. -As Water freezes into ice, the ice consists of a positive charge -A thundercloud has a positive charge at the top and a negative charge at the base -It is still uncertain how the thunderclouds obtian the polarization necessary for lighting formation, but many believe ice is involved. |
The Different Theories of Cloud Polarization
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Hypothesis 1 After water freezes at top of cloud, rising air tears small droplets of water away from frozen particles, the droplets are concentrated in the upper part of the cloud and the larger particles fall to the base of the cloud |
Hypothesis 2 Large, swiftly falling drops of water become negatively charged wheras small, slowly falling drops become positively charged. |
However the electrical charge is formed in the thundercloud, the base of the cloud induces a positive charge on the earth beneath it, therefore making the earth act as the second plate of a huge capacitor. (device for storing an electrical charge) When the electrical potential between two clouds or between a cloud and the eareth reaches a high value such as 10,000 volts per centimeter, the air becomes ionized along a narrow path and a lightning flash occurs. A lot of meteorologists this is the how a negative charge is carried to the ground and the total negative charge of the surface of the earth is maintained.
Well there you have it! That is how lighting occurs.
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Copyright 2001 Nate, and Kavi. This website was created using Dreamweaver 4, Microsoft FrontPage 2000, and Eversoft 1st page 2000 (free verstion). This website was created for Thinkquest.org, for a website competition. More information about this contest can be found here. We are team C0120505.