By DAN ROBINSON Storm Chaser/Photographer

Storm Highway on Facebook

On a small scale, all lightning is essentially the same - a channel of ionized air carrying electrical current between two differing areas of charge. The polarity of lightning discharge can affect the way it propagates and branches in space and time, but in the end, it's all an electrostatic discharge - a 'spark' in its fundamental sense. The little 'static' sparks between your finger and a doorknob are, technically speaking, the same basic process at work, just on a smaller scale. The 'types' of lightning we'll discuss here refer more to how a discharge appears to an observer, what the starting and ending terminii of the channel are, and in what direction the formation of the channel took place.

Cloud-to-Ground Lightning

Cloud-to-Ground Lightning A lightning discharge between cloud and ground initiated by a downward-moving stepped leader. CGs can be either positive or negative in polarity. ARTICLE: In-depth look at cloud-to-ground lightning PHOTOS: Cloud-to-Ground Lightning Gallery

Ground-to-Cloud Lightning

Ground-to-Cloud Lightning Ground-to-Cloud lightning (sometimes called Upward-moving lightning) is a discharge between cloud and ground initiated by an upward-moving stepped leader originating from an object on the ground. Ground-to-Cloud lightning strikes are common on tall towers and skyscrapers. GC lightning can also be either positive or negative in polarity. ARTICLE: Article: In-depth look at ground-to-cloud lightning PHOTOS: Ground-to-Cloud (Upward) Lightning Gallery

Intracloud Lightning

Intracloud Lightning The most common type of discharge - lightning inside a single storm cloud, jumping between different charge regions in the cloud. Intracloud lightning is sometimes called sheet lightning because it lights up the sky with a 'sheet' of light. All or parts of the actual channel may be obscured inside the cloud, and may or may not be visible to an observer on the ground. Not to be confused with cloud-to-cloud lightning. PHOTOS: Intracloud/Anvil Crawler Lightning Gallery

Anvil Crawler

Anvil Crawlers Anvil Crawlers are horizontal, tree-like, in-cloud lightning discharges whos leader propagation is resolvable to the human eye. In other words, the anvil crawler's movement is slow enough (compared to most lightning discharges) that a human observer or normal-speed video camera can see its rapid motion across the sky. This type of lightning (sometimes referred to as 'crawlers' or 'rocket lightning') often cover very large distances, resulting in vast, spectacular sky-filling discharges. Anvil crawlers are often very high-altitude events, and as such typically result in soft, rolling thunder due to their great distance from the observer. The name 'anvil crawler' is derived from the visible 'crawling' motion and their tendency to appear along the underside of the anvil portions of a thunderstorm. Anvil crawlers can either occur independently completely within the cloud, or in connection with a cloud-to-ground discharge. Click the images below to enlarge PHOTOS: Intracloud/Anvil Crawler Lightning Gallery

Bolt from the Blue

Bolt from the Blue A bolt from the blue (sometimes called 'anvil lightning' or 'anvil-to-ground' lightning) is a name given to a cloud-to-ground lightning discharge that strikes far away from its parent thunderstorm. A 'bolt from the blue' typically originates in the highest regions of a cumulonimbus cloud, traveling horizontally a good distance away from the thunderstorm before making a vertical descent to earth. Due to the final strike point being a significant distance from the storm (sometimes up to ten miles away), these lightning events can occur at locations with clear 'blue' skies overhead - hence the name. While many 'bolts from the blue' are positive flashes, some are not.

Sheet Lightning

Sheet Lightning Sheet Lightning is a term used to describe clouds illuminated by a lightning discharge where the actual lightning channel is either inside the clouds or below the horizon (not visible to the observer).

Bead Lightning

Bead Lightning Bead Lightning is a name given to the decaying stage of a lightning channel in which the luminosity of the channel breaks up into segments. Nearly every lightning discharge will exhibit 'beading' as the channel cools immediately after a return stroke, sometimes referred to as the lightning's 'bead-out' stage. 'Bead lightning' is more properly a stage of a normal lightning discharge rather than a type of lightning in itself. Beading of a lightning channel is usually a small-scale feature, and therefore is often only apparent when the observer/camera is close to the lightning. PHOTOS: Bead Lightning Gallery

Ribbon Lightning

Ribbon Lightning Ribbon Lightning refers to the visual appearance of a photographed lightning flash's individual return strokes being separated by visible gaps on the final exposure. This is typically caused by wind blowing the lightning channel sideways during the exposure. The stronger the wind and closer the lightning strike, the more horizontal displacement will exist on the recorded image. Camera movement during the capture of a lightning photograph can also result in the same effect.

Other lightning types

Cloud-to-Cloud Lightning
Somewhat rare type of discharge between two or more completely separate storm clouds. Not to be confused with common intracloud lightning occuring within one storm cloud.

Ball Lightning
Ball Lightning is a rare phenomenon described as a floating, illuminated sphere that occurs during thunderstorms. It may move fast, slow or stay stationary, it may be quiet or produce a hissing or crackling noise, it may pass through windows, last from seconds to minutes, and disappear slowly or suddenly either quietly or with a loud bang. No definitive photographs have ever been obtained of ball lightning nor has any plausible scientific explanation been found for it to occur. Therefore, its existence remains questionable and is currently given the same scientific credibility as UFOs. Furthermore, many ball lightning reports have been found to be nothing more than power line arcs and other unrelated events.

Heat Lightning
'Heat lightning' is simply ordinary lightning from faraway thunderstorms below the horizon. On a clear night, lightning flashes from a distant storm can be seen hundreds of miles away. Heat lightning got its name because it is often seen on hot summer nights, a time when thunderstorms are common. 'Heat lightning' often is early warning sign that storms are approaching, because the storm producing the lightning you're seeing could be moving your way.

Sprites and Jets
Electrical discharges that occur high above active thunderstorms. They have been found to occur in conjunction with and/or as a reaction to a normal cloud-to-ground lightning discharge. They are swift and faintly lit, making them almost invisible to the naked eye. Observations of sprites and jets have been made by placing a telescope on a high mountain and aiming it above thunderstorms occuring hundreds of miles away.

Staccato Lightning
A cloud-to-ground lightning flash that consists of only one return stroke.

This animation depicts several types of lightning. Can you identify them?