The Different Types of Lightning

Lightning just plain rocks, and it becomes even more interesting the more you learn about it. Learning about the different types of lightning is as good place start, and, as you'll see, even the most basic discussion of lightning gets weird pretty quick.

Lightning Bolts

Lightning bolts are jagged lines of electric light that pierce the sky during a thunderstorm. This type of lightning can shoot from a cloud to another cloud, down to the ground or simply out into the wide open air. Lightning bolts often form into forks of multiple bolts and can travel very far in a brief period of time, traveling as fast as 60,000 miles per second.

Ball Lightning

Ball lightning are a particularly strange form of lightning that has frightened many a sky watcher. Unlike traditional lightning, ball lightning consists of grapefruit sized ball of electric light that zip and hover in the sky before disappearing or exploding. It is unclear how exactly ball lightning forms, but scientists have recreated effects that they believe are very similar to ball lightning in a laboratory atmosphere. According to Wired magazine, the United States military has an active program that is aimed at trying to weaponize ball lightning. Ball lightning has often be used as an explanation for UFO sightings.

Heat Lightning

Heat lightning is a so called silent form of lightning that is best known for occurring in rainless clouds on hot summer nights. However, heat lightning is not actually a form of lightning onto itself. Instead, heat lightning is normal lightning that is observed at such a distance that the observer is too far away to hear the accompanying thunder. In other cases, matter in the air such as sand or snow can muffle thunder to the point that it is silenced.

Sheet Lightning

Much like heat lightning, sheet lightning is a common name to refer to a normal flash of lightning that has become masked by its environment. In this case, a flash of lightning occurs within a dense cloud and is so bright that the entire cloud is suddenly awash in light. However, there is nothing particularly unusual in the lightning itself that causes this effect.

St Elmo's Fire

St. Elmo's fire is a bizarre example of meteorological phenomena that has a long association with divine intervention in the folklore of all peoples that have witnessed it through the ages. St. Elmo's Fire is a corona discharge tearing molecules apart and creating plasma. Unlike lightning, St. Elmo's Fire occurs right at the tips of pointed objects that create a continuous blue spark that can hiss in the ionized air for several minutes. For a better understanding of what plasma is, HowStuffWorks explains that glowing neon is simply St. Elmo's fire contained in a tube.

High-altitude Lightning

Another strange example of lightning occurs at the upper limits of Earth's atmosphere. Here, the usual pressures governing lightning do not apply, leading to some truly startling sights. These are informally referred to as sprites, blue jets and elves. Sprites strangely colored halos with tendril like branches above and below the halo. Blue jets are huge bursts of blue light that have been seen by air and space craft shooting out of the tops of thunderheads. Elves are very short lived flashes that rapidly expand high in the reaches of the mesosphere.

Sources:

http://www.centennialofflight.gov/2003FF/lightning/types.html
http://en.wikipedia.org/wiki/Lightning
http://www.wired.com/dangerroom/2009/02/great-balls-of/
http://en.wikipedia.org/wiki/Ball_lightning
http://www.theweatherprediction.com/habyhints/274/
http://www.weatherquestions.com/What_is_heat_lightning.htm
http://en.wikipedia.org/wiki/Heat_lightning
http://members.core.com/~tizod/lightning/defsheet.html
http://science.howstuffworks.com/st-elmo-fire1.htm
http://www.space.com/scienceastronomy/unknown_lightning_0230626.html