Catatumbo lightning

The Catatumbo lightning is a storm that flashes over and around Lake Maracaibo in Venezuela, mostly where the Catatumbo River flows into the lake. People call it the Everlasting Storm because the lightning returns again and again.

It happens on about 140 to 160 nights a year, for around nine hours a night, with 16 to 40 flashes per minute. Scientists describe it as having the highest density of lightning in the world, about 250 flashes per square kilometre each year. The flashes come from storm clouds more than a kilometre high. The lightning also makes a great deal of ozone, although scientists argue about what that means for the sky above.

Why is there so much lightning?

Winds blowing across the lake and the nearby swamps carry warm, wet air toward the Andes, the Perijá Mountains and the Mérida range, which enclose the plain on three sides. As this air rises and becomes unstable, thunderstorms build up.

Most of the lightning flashes inside the clouds. Researchers have suggested several extra causes, such as methane from the swamps, but not all studies agree, and the exact reasons are still debated.

Does it ever stop?

Yes. The pattern changes through the year and from year to year. From January to March 2010 the lightning stopped, probably because of a drought, and people feared it was gone for good. It later returned.

The name Catatumbo means "House of Thunder" in the language of the Barí people. Scientists at the Universidad del Zulia have linked the changes to large weather patterns, such as the belt of rain-bearing winds near the equator.

On the globe

Find it on the globe over Lake Maracaibo in Venezuela and zoom in to open its card.