Lightning is defined as an atmospheric discharge of electricity. It usually occurs during thunderstorms but it has also been seen during a dust storm or a volcanic eruption or a forest fire.
Cloud-to-Ground Lightning
Lightning can travel from a cloud to the ground and this is the most dangerous form of lightning and is not seen during every storm. The storm clouds become charged with negative ions. On the ground, objects and the soil become charged with positive ions. The opposite ions attract each other and cause an electrical discharge, which manifests in the form of lightning.
From the cloud, a step leader initiates a bolt of lightning. From the ground, a streamer discharges and hits the step leader. In turn, the lightning will strike the ground and this is known as return strokes.
Lightning will follow the path of least resistance when striking the ground. It will hit the tallest object in its path, such as a tower, a tree, an open aired structure or sometimes a person who is out in an open space. Lightning can strike when a storm is ten miles away.
Cloud-to-Cloud Lightning
Lightning can travel from cloud to cloud and not necessarily touch the ground. This occurs when there are positive and negative electrons located in different clouds. When the charges build up, they are attracted to each other and discharge between clouds.
During a storm, bolts of lightning can be seen inside a cloud or escaping from the cloud. This is also known as sheet lightning because it can be seen as bright light behind the clouds. Another name is inter-cloud lightning. This is the most spectacular lightning because it lights up the entire sky.
Intra-Cloud Lighting
This type of lightning occurs when positive and negative electrons reside in the same cloud. As the charge builds, the discharge looks like a bright, flickering light. The flash may also escape from the cloud. This is the most common type of lightning and can be seen from far distances.
Ball Lightning
Little is known about ball lightning. It is not discharged from clouds but it is sometimes triggered after a lightning strike on the ground. It is described as a baseball-sized glowing light and it makes a hissing sound. It has been seen floating in the air or rolling on the ground.
It lasts for approximately 30 seconds and then disappears after making a soft explosive sound. Ball lighting is very hot and has been known to melt glass and sand or dig up the earth or penetrate walls.
Different Forms of Lightning
- Forked lightning has several visible branches.
- Ribbon lightning shows parallel streaks of light and is caused by wind breaking the bolt.
- Streak lightning is arc-shaped.
- Chain lightning is also known as bead lightning. This is a bolt that diminishes to dotted lines.
- Blue jets are conical-shaped flashes that rise up and over the tops of thunderclouds.
- Red sprites are light red bursts of lightning that rise above the storm clouds.
- Elves are flat and wide flashes of green light that burst far above the thunderclouds.
There are several contributing factors that cause lightning, such as solar wind, ice in the clouds, humidity, wind, atmospheric pressure and friction, but the exact cause is still not known.
Sources
Montana, Sam. The Different Types of Lightning. Factoidz. Accessed February 18, 2011.
Types of Lightning. 2003 Flight Forecast. U.S. Centennial of Flight Commission & The Franklin Institute Online. Accessed February 18, 2011.
Types of Lightning. Oracle ThinkQuest Educational Foundation. Accessed February 18, 2011.
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