The lightning is a most powerful electric discharge which arises at strong electrization of clouds. Lightning discharges can happen both in a cloud, and between the next clouds which are strongly electrified. Sometimes the category happens between the earth and the electrified cloud. Before flash of a lightning there are differences of electric potentials between a cloud and the earth or between the next clouds.
The American scientist who in combination held an important state post - Benjamin Franklin was one of the first who established interaction of electric discharges in the sky. In 1752 it made useful experience with a kite. The tester attached a metal key to its cord and in time started thunderstorms a snake. after a while, lightning struck in a key, letting out a sheaf of sparks. Since then the lightning began to be studied by scientists in detail. This surprising natural phenomenon can be extremely dangerous, putting serious damages to power lines and other high constructions. The main reason for emergence of a lightning is in collision of ions (shock ionization). Electric field of a cloud has very big tension. In such field the free electrons receive huge acceleration. Facing atoms, they ionize them. Finally there is a stream of fast electrons. Shock ionization forms the plasma canal across which there passes the main impulse of current. There is an electric discharge which we observe in the form of a lightning. Length of such category can reach several kilometers and proceed up to several seconds. The lightning is always followed by bright flash of light and a thunder. Very often lightnings arise during a thunderstorm, however there are also exceptions. One of the most natural phenomena which are not studied by scientists connected with electric discharges is the fireball. It is known only that there is it suddenly and can cause significant damage. So why so bright lightning? Force of electric current at lightning stroke can reach 100,000 Amperes. At the same time huge energy (about one billion Joules) is emitted. Temperature of the main channel reaches nearly 10,000 degrees. These characteristics also give rise to bright light which can be observed at lightning discharge. After such powerful electric discharge there comes the pause which can last from 10 to 50 seconds. During this time the main channel almost dies away, temperature in it falls up to 700 degrees. By scientists it is established that the bright luminescence and heating of the plasma channel extend from below up, and pauses between luminescences make only dozens of shares of seconds. For this reason several powerful impulses of people perceive as uniform bright flash of a lightning.