We all know Ben Franklin's 1752 experiment with lightning - flying a kite in a thunder storm with a brass key tied to a kite string. But did you know that it was Franklin who invented lightning rods?
Thunderstorms form in cumulonimbus clouds. Drops of water, hailstones and specks of ice, rub and bump against each other as they do they become charged with electricity. After a while, the whole cloud fills up with electrical charges. There are positive charges (called protons) and negative charges (called electrons) in electricity and during the storm these charges separate. The positive charges form at the top of the cloud and negative charges form at the bottom of the cloud.
Positive and negative charges are attracted to each other and as they travel through the air they create an electric current which causes a spark, this is lightning. So lightning happens inside a cloud and between clouds. Intracloud lightning happens in the same cloud and is the most common type of lightning. Intercloud lightning happens between two different clouds and the strike travels in the air between them.
As the storm builds the negative electrical charge at the bottom of a cloud are attracted to the positive charge in the ground below. As the negative charge get stronger, the air cannot stop it from jumping from the cloud towards the positive charge on the ground. The giant spark of electricity is the lightning that we see.
As the lightning heats the air around it, the air expands outwards at great speed, and there is a hole left in the air, called a channel. When the lightning is gone, the air collapses back in, creating the sound that we hear as thunder.
Forked lightning appears as jagged or crooked lines of light. They can have several branches. Forked lightning can be seen shooting from the clouds to the ground, from one cloud to another cloud, or from a cloud out into the air. This lightning can strike up to 10 miles away from a thunderstorm and appear to be coming out of a clear blue sky. The phrase, "out of nowhere" or "out of the clear blue" might well describe some of these forked lightning strokes.
Sheet lightning appears as flashes of light that seems to light up or illuminate entire clouds. This makes the clouds visible far away. Intracloud lightning is sometimes called sheet lightning because it lights up the sky with a 'sheet' of light.
'Heat lightning' is simply ordinary lightning from faraway thunderstorms below the horizon. Heat lightning is created by thunderstorms that are usually more than 10 miles away. The reason it is called heat lightning is that it appears most often in the hot summer when the sky overhead is clear and most often is too far away to be heard.
Ball lightning is very rare. (In fact some scientists say it does not exist at all.) Reports of ball lightning have been made by passengers on planes and ships as well as from people that experienced it in their homes. These form of lightning appears as a glowing ball less than three feet wide. It lasts from a few seconds to several minutes and then disappears. Usually there is no damage from ball lightning except for burn marks left where it traveled through screens or windows. Therefore, its existence remains questionable and is currently given the same scientific credibility as UFOs. Many of the ball lightning reports have been found to be nothing more than power line arcs and other unrelated events.
St. Elmo's Fire appears as a blue or greenish glow above pointed objects on the ground. It was named for the patron saint of sailors. It is created when tiny positively charged sparks reach up in response to negative charges in the air or clouds above the ground. Instead of a lightning strike the glow appears from objects such as a ship's mast, a power pole, tall antennae, or the wings of an aircraft. If a thunderstorm is nearby, St. Elmo's Fire might be seen right before a lightning strike.
High-altitude lightning has been given other names such as "red sprites," "green elves," and "blue jets." This form of lightning appears as brightly colored flashes, high above thunderstorms. These flashes shoot up above the thunderstorm about the same time as other lightning discharges inside the storm cloud.
Lightning has always fascinated mankind. It was like fire in the sky, which sometimes fell to earth. As early man sought answers about their world, lightning became a part of the superstitions, myths and many early religions.
Lightning has been thought to be a weapon of mystical or powerful gods. The Greeks were amazed by lightning but feared it as they thought it was hurled by a god named Zeus. Thunderbolts were invented by Minerva the goddess of wisdom. Since lightning was a product of the gods any place that lightning hit became scared.
Moslems also attributed lightning and thunder to their god. The Koran says "He it is who showeth you lightning and launches the thunderbolts."
The Vikings thought that a god named Thor produced lightning as his hammer struck an anvil while he rode his chariot across the clouds. Thor also gave us Thurs-day.
Early statues of Buddha showed him carrying a thunderbolt that had arrows at each end.
Even Indian tribes in North America gave lightning a mysterious origin. They believed that lightning was caused by a mystical bird whose feathers flashed with light. They also thought that the flapping of the wings produced the thunder they heard.
During the Napoleonic wars, more than 220 British tall ships were damaged, by lightning. The solution, of course, was to install lightning rods recently invented by Ben Franklin. But since that device had been invented by a "rebel colonist" , His Majesty's Navy steadfastly refused. It took until the 1830's before the admiralty finally saw the light and forgot about old colonial rebellions.