What causes lightning?
Lightning is an electric current. Within a thunder cloud way up in the sky, many small bits of ice bump into each other as they move around in the air. All of those collisions create an electric charge. After a while, the whole cloud fills up with electrical charges. The positive charges or protons form at the top of the cloud and the negative charges or electrons form at the bottom of the cloud. Since opposites attract, that causes a positive charge to build up on the ground beneath the cloud. The grounds electrical charge focuses around anything that sticks up, such as mountains, people, or single trees. The charge coming up from these points eventually connects with a charge reaching down from the clouds and - zap -lightning strikes!
What is lightning?
Lightning is a bright flash of electricity produced by a thunderstorm. All thunderstorms produce lightning and are very dangerous. If you hear the sound of thunder, then you are in danger from lightning. Lightning put simply, is a bright flash of electricity, caused during a thunderstorm. Besides thunderstorm, lightning can also be observed during volcanic eruptions, surface nuclear explosions and forest fires. It travels up to a speed of 60,000 meters per second. Florida in the US has the maximum number of lightning strikes each year than any other part of the US.
Theories
The first theory describes how ice gains a negative charge while frozen and unfrozen water keeps its positive charge. Another theory shows how when large droplets fall quickly, they gain a negative charge, while slowly falling water gains a positive charge.
Theories that do not need ice gives the explanation that the cloud gets its charge by getting negative charges from the ionosphere. These negative charges are pushed to the base of the cloud by strong downdrafts, while the positive particles are pushed upwards by warm air within the rain cloud.
Theories that do not need ice gives the explanation that the cloud gets its charge by getting negative charges from the ionosphere. These negative charges are pushed to the base of the cloud by strong downdrafts, while the positive particles are pushed upwards by warm air within the rain cloud.
How lightning works
Lightning's first spark is a streak of electricity known as a "stepped ladder," which begins forcing its way through the air in 50-yard bursts, looking for the path of least resistance between one charged region and the other. Once it connects with the opposite region's most convenient point, a glowing returns stroke blasts back along the same path at 60,000 miles per second. A flash consists of one or up to 20 return strokes along the same lightning channel — usually about 1 to 2 inches in diameter — but it all happens faster than you can say greased lightning.
If a lightning flash takes only a fraction of a second, how come thunder lasts so long?
While we see the flash virtually occurring, the beginning and end points might be 5 or more miles apart. Due to the slower speed of sound, it takes differing lengths of time for the shock wave to reach our ears. If the lightning channel was two miles long, and assuming it started directly overhead, it would take at least 10 seconds for the rumbling to stop.