Caption: "Lightning over the outskirts of Oradea, Romania, during the 2005 Aug17 thunderstorm which went on to cause major flash floods over southern Romania."
Lightning occurs when a large electric charge separation builds up between clouds and ground or clouds and clouds. The electric charge separation causes a strong electric field that in turn causes an electrical breakdown of the air turning it into an electrical conductor of ions and free electrons. Then a strong electrical current flows in a somewhat chaotic way between the separated electric charge regions converting electrical potential energy into the energy of electromagnetic radiation (the lightning light), heat, and sound (the thunder). Lightning is, of course, a plasma.
The electrical potentials of lightning can go up to ∼ 100 megavolts (MV) and the discharges typically have currents of ∼ 30 megaamperes. Lightning emits visible light, ultraviolet infrared, radio, X-rays, and even gamma rays. Temperatures may approach ∼ 28,000 K and electron densities may exceed 10**24 m**(-3).
Credit/Permission:
Mircea Madau,
User:Lucas,
2005 /
Public domain.
Image link: Wikipedia:
File:Lightning over Oradea Romania zoom.jpg.
Local file: local link: lightning.html.
File: Earth atmosphere file:
lightning.html.