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"Catatumbo lightning" refers to continuous (high frequency) lightning from a near-daily thunderstorm complex that forms in the Lago de Maracaibo/Catatumbo River region in northern Venezuela, South America. The only apparent unique characteristic of this phemonemon is that the storms form and persist in the same place night after night - with enough reliable frequency to even be a maritime navigational aid.
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Fig. 1: Above: A Catatumbo-like thunderstorm complex in Illinois, with near-continuous lightning through the nighttime hours. View more photos and video
Contrary to myths, the type of thunderstorm, and attendant lightning, produced with the Catatumbo storms are no different from highly electrified thunderstorm complexes commonly seen in many parts of the world. In other words, "Catatumbo lightning" isn't a rare or different type of lightning, and the storms are not in a different class than ones observed elsewhere. The single remarkable feature of the Catatumbo storms is their formation in the same place and at the same time for (what many sources say is) nearly half of the nights throughout the year.
Long-lived, highly electrified thunderstorm complexes (called an MCS: Mesoscale Convective System) are common at night in many parts of the world, particularly in the Plains and Midwest regions of the United States during spring and summer. During the night, a wind configuration called a low level jet (LLJ) often develops. The LLJ consists of a narrow corridor of winds near the surface that flows generally northward. The LLJ is usually carrying warm, moist and unstable air from the south. When the LLJ encounters a frontal boundary, this unstable air is forced upward - often triggering strong, large thunderstorm complexes (MCSs) that last through the nighttime hours. The LLJ tends to weaken after sunrise, after which the nocturnal storms will wane and dissipate.
MULTIMEDIA LINK: View photos and video of a nocturnal MCS in Illinois, USA
"Catatumbo lightning" in Venezuela is produced by thunderstorm complexes that form due to 'diurnal' (meaning on a day/night cycle) wind patterns produced as a result of the local topography and maritime factors. Mountains surround the Lago de Maracaibo basin, which influence wind patterns that promote convergence zones at the surface, much like a LLJ does with a frontal boundary. These convergence zones form nightly and in generally the same location in the Lago de Maracaibo basin, creating the thunderstorms that produce the famed Catatumbo lightning.
Fig. 2: Below: Google Maps topo image of the Lago de Maracaibo basin in northern Venezuela.
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Catatumbo lightning: Myths
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The primary myths about Catatumbo lightning concern the methane gas from the local bogs and swamps. The methane is often cited as a cause and/or a contributing factor for both the thunderstorms and the lightning itself. This is highly unlikely, as thunderstorm formation requires large-scale atmospheric forces: instability, moisture and lift. The topography, wind configuration and tropical climate in the Lago de Maracaibo region alone produces these three ingredients that trigger the storms - any methane produced by the swamps is an irrelevent factor. There are other locations on earth with similar topographical configurations that also generate frequent thunderstorms without the presence of swamps and gases [1]. The methane gas has also been attributed to making the lightning appear colored with an orange/yellow hue. This is also a myth, as the Catatumbo storms are often observed at great distances. Distant lightning observed anywhere on earth will tend to have an orange/yellow/brown cast due to atmospheric particulates, much in the same way that the setting sun is affected.
Fig. 3: Below: A thunderstorm with lightning in Illinois, viewed from 45 miles away. Distant lightning appears orange due to atmospheric particulates, in the same way the setting sun produces an orange cast.
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The last common myth regarding Catatumbo lightning is that it rarely produces thunder, due to either 1.) the lightning being a special type that produces no thunder or 2.) the lightning being primarily at high altitudes within the cloud. All lightning produces thunder - if thunder is inaudible, it is due to the observer being too far away to hear it. Thunder is rarely audible to an observer at distances of more than 15 miles away from the lightning. Even lightning inside the highest reaches of a thunderstorm will still be audible to an observer who is within a few miles of the storm base. The fact that 'Catatumbo lightning' is rarely audible correlates with its described colored appearance, as both are characteristics of lightning occurring great distances from the observer. Furthermore, video and photographs do not indicate that cloud-to-ground discharges are rare in the Catatumbo storms (as the myths suggest) - so the lack of thunder can be fully explained by the great distances between the observers and the lightning.
Observing Catatumbo lightning
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If you were to travel to Venezuela to observe Catatumbo lightning, you wouldn't see a new, rare type of thunderstorm or lightning. You'd find the same thing that you'd see with any high-lightning-frequency storm in the US. If you've ever witnessed a storm with near-continuous lightning (like this one in Illinois), then you've seen the equivalent of Catatumbo lightning. The only characteristic that makes Catatumbo lightning unique is the storms' near-daily formation in exactly the same location in the Lago de Maracaibo region of Venezuela.
References/More Information
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1. AMS Journal Article: Diurnal Patterns of Rainfall in Northwestern South America
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