Lightning Types and Classifications By DAN ROBINSON Storm Highway Editor/Cameraman Cloud-to-Ground Lightning Cloud-to-Ground Lightning A lightning discharge between cloud and ground initiated by a downward-moving stepped leader. Article: In-depth look at cloud-to-ground lightning 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. Article: In-depth look at ground-to-cloud lightning 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. 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 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. Click the images below to enlarge 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-Air Lightning Referring to a discharge (or a portion of a discharge) jumping from a cloud into clear air. Technically speaking, all cloud-to-ground lightning strikes contain 'cloud-to-air' components in the many branches that extend away from the main channel and terminate abruptly in mid-air. However, the most visually dramatic examples of cloud-to-air lightning occur when a long, bright lightning channel jumps out of the side of a cumulonimbus cloud and terminates in the clear air surrounding the storm. 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? Weather Library Index | Extreme Weather Gallery | Storm Highway Home

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